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Melanie's MCAT flashcards > Bio/Biochem > Flashcards

Bio/Biochem Flashcards

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1
Q

What is a peptide hormone?

A

Chemical precursor = amino acids, location of receptor = extracellular, mechanism of action = initiates a signal cascade, method of travel in the bloodstream = dissolves freely, speed of onset = quick, duration of action = short-lived

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2
Q

What is a steroid hormone?

A

Chemical precursor = cholesterol, location of receptor = intracellular/intranuclear, mechanism of action = binds to a receptor and induces conformational change, method of travel in the bloodstream = binds to a carrier protein, speed of onset = slow, duration of action = long-lived

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3
Q

What is a direct hormone?

A

Direct hormones are secreted into the bloodstream, has a direct effect on a target tissue

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4
Q

What is a tropic hormone?

A

Tropic hormones cause secretion of another hormones that then travels to the target tissue to cause an effect (“FLAT” in “FLAT PEG”)

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5
Q

What is the hormone from the anterior pituitary/target organ does CRF affect?

A

Corticotropin-releasing factor (CRF) affects the ACTH hormone in the anterior pituitary, which affects the adrenal cortex, which releases glucocorticoids (cortisol and cortisone) from the adrenal cortex

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6
Q

Which endocrine tissue synthesizes catecholamines?

A

Adrenal medulla, which produces epinephrine and norepinephrine

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7
Q

What is aldosterone?

A

Aldosterone increases sodium reabsoprtion in the distal convoluted tubule and collecting duct of the nephron (increases blood volume and pressure)

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8
Q

What is ADH?

A

ADH increases water reabsorption and decreases plasma osmolarity in collecting ducts (without ADH, collecting duct is almost impermeable to water) - increases blood pressure and volume due to increased volume

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9
Q

What is ANP?

A

ANP increases glomerular filtration (lowers blood pressure)

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10
Q

Which muscles are involved in inhalation? Exhalation?

A

The external intercostal muscles and diaphragm are involved in inhalation, the external intercostal muscles are involved in exhalation

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11
Q

If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?

A

The brain decreases its respiratory rate to increase CO2

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12
Q

What are some of the mechanisms used in the respiratory system to prevent infection?

A

Vibrissae in the nares, lysozyme in the mucous membranes, the mucociliary escalator, macrophages in the lungs, mucosal IgA antibodies, and mast cells

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13
Q

Increased synthetic activity of the parathyroid glands would lead to:

A

An increase in renal calcium reabsorption

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14
Q

Iodine deficiency may result in:

A

Cretinism

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15
Q

Which hormones listed are steroid/peptide hormones? (Aldosterone, Estrogen, Oxytocin, Progesterone)

A

Aldosterone, Estrogen, Progesterone = Steroid hormones, Oxytocin = Peptide hormone

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16
Q

What is a fact about pancreatic somatostatin?

A

It is always inhibitory

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17
Q

A blocking of dopamine receptors would cause:

A

Increased secretion of prolactin

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18
Q

A female born with ambiguous genitalia and low sodium concentration would affect:

A

Adrenal cortex

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19
Q

What makes up the intrapleural space?

A

The parietal pleura and the visceral pleura

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20
Q

How would the stiffening of the lung tissue affect the body?

A

Decreased inspiratory reserve volume

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21
Q

If mucus or pus built up within an entire lobe of the lung, how would this affect diffusion of gas?

A

No diffusion would occur in the affected area

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22
Q

What does hyperventilation cause?

A

A decrease in blood carbon dioxide, so breathing air from a bag helps to readjust blood levels of carbon dioxide

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23
Q

What is the point of using positive end-expiratory pressure for premature infants?

A

Prevent alveoli from collapsing on each other (similar to the point of surfactant)

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24
Q

What is a mast cell?

A

A mast cell is what is attached to an antibody, can release inflammatory mediators that cause allergic reactions

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25
Q

What is a nucleoside?

A

Five-carbon sugar (pentose) and nitrogenous base

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26
Q

What is a nucleotide?

A

Five-carbon sugar (pentose), nitrogenous base, and one to three phosphate groups

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27
Q

What are the base-pairing rules according to the Watson-Crick model?

A

A pairs with T/U using two hydrogen bonds, C pairs with G using three hydrogen bonds

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28
Q

How does the aromaticity of purines and pyrimidines underscore their genetic function?

A

Aromatic = stable and unreactive (stability is important for stroing genetic information and avoiding spontaneous mutations)

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29
Q

If a strand of RNA contained 15% cytosine, 15% adenine, 35% guanine, and 35% uracil, would this violate Chargaff’s rules?

A

This would not violate Chargaff’s rules because the complimentarity seen in DNA does not hold true (should have a 1:1 ratio of purines and pyrimidines)

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30
Q

What is helicase?

A

Unwinds DNA double helix, present in prokaryotes and eukaryotes

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31
Q

What is single-stranded DNA-binding protein?

A

Prevents reannealing of DNA double helix during replication, present in prokaryotes and eukaryotes

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32
Q

What is DNA polymerase III?

A

Adds nucleotides to growing daughter strand (synthesizes DNA), present in prokaryotes

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33
Q

What is DNA polymerase alpha?

A

Adds nucleotides to growing daughter strand (synthesizes DNA), present in eukaryotes

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34
Q

What is DNA polymerase I?

A

Fills in gaps left behind after RNA primer excision (removes RNA primers, replaces RNA with DNA), present in prokaryotes

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35
Q

What is RNAse H?

A

Excises RNA primer, present in eukaryotes

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36
Q

What is DNA ligase?

A

Joins DNA strands (especially between Okazaki fragments)

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37
Q

Between the leading and lagging strand, which is more prone to mutations?

A

Lagging strand because it constantly starts and stops the process of DNA replication, and it contains many more RNA primers

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38
Q

What are telomeres?

A

Telomeres are the ends of eukaryotic chromosomes and contain repetitive sequence of noncoding DNA, they protect the chromosome from losing important genes from the incomplete replication of the 5’ end of the DNA strand

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39
Q

What is an oncogene?

A

Oncogenes code for cell cycle-promoting proteins

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40
Q

What is a tumor suppressor gene?

A

Tumor suppressor genes code for repair or cell-cycle inhibiting proteins

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41
Q

What is the difference between the parent strand and the daughter strand?

A

The parent strand is more heavily methylated, and the daughter strand is barely methylated at all

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42
Q

Give some information about DNA polymerase (proofreading).

A

Involved in S phase of cell cycle, key enzyme/gene = DNA polymerase

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43
Q

Give some information about mismatch repair.

A

Involved in G2 phase of cell cycle, key enzymes/genes = MSH2, MLH1 (MutS and MutL in prokaryotes)

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44
Q

Give some information about nucleotide excision repair.

A

Involved in G1 and G2 phases of cell cycle, key enzymes/genes = excision endonuclease

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45
Q

Give some information about base excision repair.

A

Involved in G2 and G2 phases of cell cycle, glycosylase, AP endonuclease

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46
Q

What is a genomic library?

A

Genomic libraries include all of the DNA in an organism’s genome, including noncoding regions (useful for studying introns, centromeres, telomeres)

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47
Q

What is a cDNA library?

A

cDNA libraries only include expressed genes from a given tissue, but can be used to express recombinant proteins or to perform gene therapy

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48
Q

What is PCR?

A

PCR increases the number of copies of a given DNA sequence and can be used for a sample containing very few copies of the DNA sequence

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49
Q

What is Southern blotting?

A

Southern blotting searches for a particular DNA sequence

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50
Q

During DNA sequence, why does the DNA polymer stop growing once a dideoxyribonucleotide is added?

A

Dideoxyribonucleotide lacks the 3’ -OH that is required for DNA strand elongation

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51
Q

What is a transgenic mouse?

A

Transgenic mice have a gene introduced into their germ line or embryonic stem cells to look at the effects of that gene

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52
Q

What is a knockout mouse?

A

Knockout mice are those in which a gene of interest has been removed

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53
Q

Which of the following biomolecules is LEAST likely to contin an aromatic ring?

A

Carbohydrates

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54
Q

For a compound to be aromatic:

A

The molecule is cyclic, contains 4n + 2pi electrons, and planar

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55
Q

Restriction endonucleases are used for which of the following?

A

Gene therapy, southern blotting, and DNA repair

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56
Q

Why might uracil be excluded from DNA but NOT RNA?

A

Cytosine degradation results in uracil

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57
Q

What is mRNA?

A

a single-stranded RNA molecule that corresponds to the genetic sequence of a gene

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58
Q

What is tRNA?

A

tRNA translates nucleic acids to amino acids by pairing its anticodon with mRNA codons

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59
Q

What is rRNA?

A

rRNA forms much of the structural and catalytic component of the ribosome, acts as a ribozyme to create peptide bonds between amino acids

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60
Q

What does RNA polymerase I do?

A

RNA polymerase I synthesizes most rRNA

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61
Q

What does RNA polymerase II do?

A

RNA polymerase II synthesizes mRNA (hnRNA) and snRNA, binds to the TATA box

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62
Q

What does RNA polymerase III do?

A

RNA polymerase III synthesizes tRNA and some rRNA

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63
Q

What is alternative splicing?

A

Alternative splicing is the ability of some genes to use various combinations of exons to create multiple proteins from one hnRNA transcript

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64
Q

What occurs in the A site?

A

Binds incoming aminoacyl-tRNA using codon-anticodon pairing

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65
Q

What occurs in the P site?

A

Holds growing polypeptide until peptidyl transferase forms peptide bond and polypeptide is handed to A site

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66
Q

What occurs in the E site?

A

Transiently holds uncharged tRNA as it exits the ribosome

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67
Q

What are some of the posttranslational modifications?

A

Proper folding by chaperones, formation of quaternary structure, cleavage of proteins or signal sequences, and addition of other biomolecules

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68
Q

What type of operon is the trp operon? The lac operon?

A

The trp operon is a negative repressible system, the lac operon is a negative inducible system

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69
Q

What is the regulator gene?

A

Transcribed to form repressor protein

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70
Q

What is the promoter site?

A

Site of RNA polymerase binding (similar to promotes in eukaryotes)

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71
Q

What is the operator site?

A

Binding site for repressor protein

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72
Q

What is the structural gene?

A

The gene of interest; its transcription is dependent on the repressor being absent from the operator site

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73
Q

What is the relationship between signal molecules, transciption factors, and response elements?

A

Signal molecules are transcription factors that use their DNA-binding domain to attach to a response element so that the transcription factors can increase expression of the relevant gene

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74
Q

Do histone deacetylation and DNA methylation up or downregulate transcription?

A

Downregulate, increasing proportion of heterochromatin

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75
Q

What role does peptidyl transferase play in protein synthesis?

A

It catalyzes the formation of a peptide bond

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76
Q

Enhancers are transcriptional regulatory sequences that function by enhancing the activity of:

A

RNA polymerase at a single promoter site

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77
Q

What are the four chambers of the heart and their valves?

A

Right atrium = tricuspid valve, right ventricle = pulmonary valve, left atrium = mitral (bicuspid) valve, left ventricle = aortic valve

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78
Q

What are arteries?

A

Carries blood away from heart, thick walls, a lot of smooth muscle, does not contain valves

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79
Q

What are capillaries?

A

Carries blood from arterioles to venules, very thin walls, no smooth muscle present, does not contain valves

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80
Q

What are veins?

A

Carries blood towards the heart, thin walls, a little of smooth muscle present, does contain valves

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81
Q

Why does the right side of the heart contain less cardiac muscle than the left side?

A

The right side of the heart pumps blood into a lower-resistance circuit at a lower pressure, so it requires less muscle

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82
Q

If all autonomic input to the heart were cut, what would happen?

A

The heart would continue beating at the intrinsic rate of the pacemaker (SA node), the individual would be able to change his or her heart rate

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83
Q

What are the components of plasma?

A

Plasma is an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins

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84
Q

If an individual with B+ was in an accident, who could the person receive/donate blood to?

A

Could receive from O+, O-, B+, B- ; could donate to B+, AB+

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85
Q

What does a hematocrit measure?

A

Hematocrit meausres the percentage of a blood sample occupied by red blood cells

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86
Q

What types of leukocytes are involved in the specific immune response?

A

Lymphocytes

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87
Q

Where do platelets come from?

A

Cellular fragments or shards that are given off by megakaryocytes in the bone marrow

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88
Q

Which cell types contain/ do not contain nuclei?

A

Leukocytes contain nuclei, erythrocytes and platetes do not contain nuclei

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89
Q

If capillary beds open in the body, how will that affect blood pressure?

A

Capillaries open -> less resistance -> raise heart rate -> dangerous

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90
Q

What direction does the oxyhemoglobin dissociation curve shift as a result of exercise?

A

The oxyhemoglobin curve shifts to the right during exercise in response to increased arterial CO2, increased H+, decreased pH, and increased temperature (decreased affinity for oxygen)

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91
Q

Exposure of which subendothelial compounds start the coagulation cascade? Which protein helps stabilize the clot?

A

Cascade started by exposure to platelets and coagulation factors, clot is stabilized by fibrin

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92
Q

Which of the following is the correct sequence of a cardiac impulse?

A

SA node -> atria -> AV node -> bundle of His -> Purkinje fibers -> ventricles

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93
Q

Hemoglobin’s affinity for O2:

A

Decreases as blood pH decreases

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94
Q

Which of the following is true regarding arteries and veins?

A

The blood pressure in the aorta is always higher than the pressure in the superior vena cava

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95
Q

At any time, there is more blood in the venous system than the arterial system. Which of the following features of veins allows for this?

A

Relative lack of smooth muscle in the wall

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96
Q

Where is the bundle of His located?

A

In a wall between the two ventricles

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97
Q

What is innate immunity?

A

Defenses that are always active against pathogens, but that are not capable of targeting specific invaders

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98
Q

What is adaptive immunity?

A

Takes longer to achieve a response, but that response targets a specific pathogen and maintains immunologic memory of the infection to mount a faster response during subsequent infections

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99
Q

What are B-cells?

A

Site of development = bone marrow, matures in bone marrow, produces antibodies, specific, humoral response

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100
Q

What are T-cells?

A

Site of development = bone marrow, matures in thymus, specific, cell-mediated response (helper = secrete cytokines, stimulates B-cells to become plasma cells), help maturate B cells, cytotoxic = kill virus-infected cells)

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101
Q

Which cells are considered granulocytes?

A

Neutrophils, eosionphils, basophils

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102
Q

Which cells are considered agranulocytes?

A

B-cells, T-cells (lymphocytes), and monocytes (macrophages)

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103
Q

What is skin’s immune defense?

A

Provides a physical barrier and secretes antimicrobial enzymes

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104
Q

What is defensins’ immune defense?

A

An example of antibacterial enzymes on the skin

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105
Q

What is lysozyme’s immune defense?

A

Antimicrobial, present in tears and saliva

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106
Q

What is mucus’ immune defense?

A

Present on mucous membranes, traps incoming pathogens

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107
Q

What is stomach acid’s immune defense?

A

An antimicrobial substance in the digestive system

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108
Q

What is normal gastrointestinal flora’s immune defense?

A

Provides competition, making it hard for pathogenic bacteria to grow in the gut

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109
Q

What is complement’s immune defense?

A

A set of proteins in the blood that can create holes in bacteria

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110
Q

Which cells are professional antigen-presenting cells?

A

Some B-cells, macrophages, dendritic cells, certain activated epithelial cells

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111
Q

What is the difference between MHCI and MHCII?

A

MHC-I is found is all nucleated cells and presents pieces of proteins (peptides) created within the cell (endogenous antigens); MHC-II is only found in antigen-presenting cells and presents proteins that result from the digestion of extracellular pathogens that have been brought in by endocytosis (exogenous antigens)

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112
Q

What stimulus activates natural killer cells?

A

Cells that do not present MHC

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113
Q

What stimulus activates neutrophils?

A

Bacteria, especially those that have been opsonized (tagged with an antibody on their surface)

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114
Q

What stimulus activates eosinophils?

A

Invasive parasites and allergens

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115
Q

What stimulus activates basophils and mast cells?

A

Allergens

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116
Q

What is the function of a plasma cell?

A

Form from B-cells exposed to antigen and produce antibodies

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117
Q

What is the function of a memory B-cell?

A

Form from B-cells exposed to antigen, lie in wait for a second exposure to a given antigen to mount a rapid, robust response

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118
Q

What is the function of a helper T-cell?

A

Coordinate the immune system through lymphokines and respond to antigen bound to MHC-II (one of the most important cells for adaptive response, activate B cells, macrophages and cytotoxic T cells)

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119
Q

What is the function of a cytotoxic T-cell?

A

Kill virally infected cells and respond to antigen bound to MHC-I

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120
Q

What is the function of a suppressor (regulatory) T-cell?

A

Keep the immune system from becoming overactive, promote self-tolerance

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121
Q

What is the functional of a memory T-cell?

A

Lie in wait until a second exposure to a pathogen to mount a rapid, robust response

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122
Q

What are the three main effects circulating antibodies can have on a pathogen?

A

Mark a pathogen for destruction by phagocytic cells (opsonization), cause agglutination of the pathogen into insoluble complexes that can be taken up by phagocytic cells, or neutralize the pathogen by preventing it from invading tissues

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123
Q

How do antibodies become specific for a given antigen?

A

B-cells that have the highest affinity for an antigen survive and proliferate, increasing their specificity

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124
Q

A T-cell appropriately passes through positive selection, but then inappropriately passes through negative selection. What will this T-cell be reactive towards?

A

Positive selection = T-cells in the thymus that are able to respond to antigen presented on MHC are allowed to survive, negative selection = T-cells that respond to self-antigens undergo apoptosis before leaving the thymus (negative selection = reactive to self-antigens)

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125
Q

Which cells account for the fact that the secondary response to a pathogen is much more rapid and robust than the primary response?

A

Memory cells

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126
Q

What is active immunity?

A

Stimulation of the immune system to produce antibodies against a pathogen

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127
Q

What is passive immunity?

A

The transfer of antibodies to prevent infection, wihtout stimulation of the plasma cells that producte these antibodies

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128
Q

If an individual had a blockage of lymph node flow, what would likely happen?

A

Edema, severe swelling of the limb, thickening of the skin

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129
Q

What structure is primarily responsible for returning materials from lymphatic circulaton to the cardiovascular system?

A

Thoracic duct, carries lymphatic fluid into the left subclavian vein

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130
Q

The absence of the thymus would leave an individual unable to mount specific defenses against which of the following types of pathogens?

A

Viruses (T-lymphocytes defend against intracellular pathogens)

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131
Q

What are some types of cells involved in cell-mediated immunity?

A

Memory cells, cytotoxic cells, suppressor cells

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132
Q

The lymphatic system:

A

Transports chylomicrons (fats) to the circulatory system, produce immune cells, remove excess fluids

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133
Q

Which type of cells is involved in antibody production?

A

Plasma cells

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134
Q

What are some examples of nonspecific defense mechanisms?

A

Skin provides a physical barrier against invasion, macrophages engulf and destroy foreign particles, an inflammatory reponse is initiated in response to physical damage

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135
Q

What is an example of adaptive immunity?

A

Memory B-cells generated through vaccination are activated when their antigen is encountered

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136
Q

What is a true statement about active and passive immunity?

A

Active immunity requires weeks to build, whereas passive immunity is acquired immediately

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137
Q

Where are most self-reactive T-cells eliminated?

A

Thymus

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138
Q

What is the response of the immune system to downregulation of MHC molecules on somatic cells?

A

Natural killer cells induce apoptosis of affected cells

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139
Q

What is the response of CD8+ T-cells when activated?

A

Secretion of cytotoxic chemicals

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140
Q

What cells are likely to cause lymphoma?

A

CD8+ T-cells, B-cells, and Th1 cells (Helper T-cells)

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141
Q

Upon encountering an antigen, only T-cells with a specific T-cell receptor are activated. This is an example of:

A

Clonal selection

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142
Q

Which cell type is a phagocyte that attacks bacterial pathogens in the bloodstream?

A

Neutrophils

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143
Q

Which type of immunity is likely to be affected by removal of the spleen?

A

Humoral immunity (spleen is where B-cells are made and proliferated)

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144
Q

What cell types are granulocytes?

A

Mast cells, eosinophils, basophils

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145
Q

What is the stereochemistry of the chiral amino acids that appear in eukaryotic proteins?

A

All are S except for cysteine

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146
Q

How to calculate pI

A

Basic amino acid = two basic pKa values (amino and side chain), acidic amino acid = two acidic pKa values (carbonyl and side chain)

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147
Q

What is the primary structure?

A

Linear sequence of amino acids in chain, stabilized by peptide (amide) bonds

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148
Q

What is the secondary structure?

A

Local structure determined by nearby amino acids, subtypes = alpha helix, beta sheet (bonds between carbonyl oxygen and amide hydrogen), stabilized by hydrogen bonds

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149
Q

What role does proline serve in secondary structure?

A

Proline’s rigid structure causes it to introduce kinks in a helix or create turns in B sheets

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150
Q

What is the tertiary structure?

A

3D shape of protein, subtypes = hydrophobic interactions, acid-base/salt bridges, disulfide links, stabilized by van der Waals forces, hydrogen bonds, ionic and covalent bonds

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151
Q

What is the quaternary structure?

A

Interaction between separate subunits of a multisubunit protein, stabilized by van der Waals forces, hydrogen bonds, covalent and ionic bonds

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152
Q

What are examples of common prosthetic groups?

A

Lipids, carbohydrates, and nucleic acids

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153
Q

How does heat and solutes denature proteins?

A

Heat denatures proteins by increasing their average KE, disrupting hydrophobic interactions, whereas solutes denature proteins by disrupting elements of secondary, tertiary, and quaternary structure

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154
Q

In a neutral solution, most amino acids exist as:

A

zwitterions

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155
Q

How many distinct tripeptides can be formed from one valine, one alanine, and one leucine?

A

6

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156
Q

Which amino acids have a chiral carbon in its side chain?

A

Threonine and Isoleucine

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157
Q

What are some reasons for conjugating proteins?

A

To direct their delivery to a particular organelle, to direct their delivery to the cell membrane, and to add a cofactor needed for their activity

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158
Q

If there is a tightly wrapped “triple helix”, which amino acid is likely to be found in the highest concentration?

A

Glycine

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159
Q

What is the function of ligase?

A

Addition or synthesis reactions, generally between large molecules; often require ATP

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160
Q

What is the function of isomerase?

A

Rearrangement of bonds within a compound

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161
Q

What is the function of lyase?

A

Cleavage of a single molecule into two products, or synthesis of small organic molecules

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162
Q

What is the function of hydrolase?

A

Breaking of a compound into two molecules using the additon of water

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163
Q

What is the function of oxidoreductase?

A

Oxidation-reduction reactions

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164
Q

What is the function of transferase?

A

Movement of a functional group from one molcule to another

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165
Q

What is the lock and key theory?

A

Active site of enzyme fits exactly around substrate, no alterations to tertiary/quaternary structure, less accurate

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166
Q

What is the induced fit model?

A

Active site of enzyme molds itself around substrate only when substrate is present, tertiary and quaternary strucutre is modified for enzyme to function, more accurate model

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167
Q

What does increasing substrate and enzyme concentration do to Vmax?

A

Increasing S increases enzyme activity until enzyme is saturated, increasing E will always increase Vmax

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168
Q

What is Km?

A

Km is a measure of the enzyme’s affinity for its substrate, as Km increases, an enzyme’s affinity for its substrate decreases

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169
Q

What is cooperativity?

A

Cooperativity are the interactions between subunits in a multisubunit enzyme or protein

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170
Q

What is the ideal temperature/pH for enzymes?

A

37 degrees C/98.6 F/310 K, 7.4 (2 for gastric enzymes, 8.5 for pancreatic enzymes)

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171
Q

What is feedback inhibition?

A

The product of an enzymatic pathway turning off enzymes further back in that same pathway

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172
Q

Why does competitive inhibition increase Km?

A

The substrate concentration has to be higher to reach half the maximum velocity in the presence of the inhibitor

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173
Q

Why does mixed inhibition increase Km?

A

Mixed inhibition will only increase Km if the inhibitor preferentially binds to the enzyme over the enzyme-substrate complex

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174
Q

What is irreversible inhibition?

A

The prolonged or permanent inactivation of an enzyme, such that it cannot be easily renatured to gain function

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175
Q

What are examples of transient/covalent modifications?

A

Examples of transient modifications include allosteric activation and inhibition. Examples of covalent modifications include phosphorylation and glycosylation.

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176
Q

What are zymogens?

A

Precursors of active enzymes, it is critical that certain enzymes (like the digestive enzymes of the pancreas) remain inactive until arriving at their target site

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177
Q

The conversion of ATP to cAMP and inorganic phosphate is most likely catalyzed by which class of enzyme?

A

Lyases

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178
Q

How do enzymes decrease the activation energy for biological reactions?

A

Modifying the local charge environment, forming transient covalent bonds, an acting as electron donors and receptors

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179
Q

Why is triaglycerol not likely to act as a coenzyme?

A

Large size, neutral charge, ubiquity in cells

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180
Q

How does the ideal temperature for a reaction change with and without an enzyme catalyst?

A

The ideal temperature is generally lower with a catalyst than without

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181
Q

What is the difference between mechanical and chemical digestion?

A

Mechanical digestion = physically breaking down food into smaller pieces, Chemical digestion = hydrolysis of bonds and breakdown of food into smaller biomolecules

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182
Q

What two main enzymes are found in saliva?

A

Salivary amylase (digests starch into smaller sugars) and lipase (digests fats)

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183
Q

What are mucous cells?

A

Secretes mucus, protects lining of stomach, increases pH (bicarbonate)

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184
Q

What are chief cells?

A

Secretes pepsinogen, digests proteins (activated by H+)

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185
Q

What are parietal cells?

A

Secretes HCl (decreases pH, kills microbes, denatures proteins, carries out some chemical digestion) and intrinsic factor (absorbs vitamin B12)

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186
Q

What are G-cells?

A

Secretes gastrin, increases HCl production, increases gastric motility

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187
Q

What is sucrase?

A

Brush border enzyme; breaks down sucrose into monosaccharides

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188
Q

What is secretin?

A

FIREMAN - Increases pancreatic secretions, especially bicarbonate to response to acid; reduces HCl secretion; decreases motility

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189
Q

What is dipeptidase?

A

Brush border enzyme; breaks down dipeptides into free amino acids

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190
Q

What is cholecystokinin?

A

Recruits secretions from gallbladder and pancreas; promotes satiety

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191
Q

What is enteropeptidase?

A

Produced in the duodenum, digests food, activates trypsinogen (zymogen), which initiates an activation cascade

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192
Q

How do bile and pancreatic lipase work together to digest fats?

A

Bile mechanically digests fats, pancreatic lipase chemically digests fats

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193
Q

What are some pancreatic enzymes that breakdown carbohydrates, proteins, and fats?

A

Carbohydrates: pancreatic amylase; proteins: trypsin, chymotrypsin, carboxypeptides A and B; fats: pancreatic lipase

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194
Q

What are the main components of bile?

A

Bile salts, pigments (bilirubin), and cholesterol

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195
Q

Where is bile synthesized, stored, and where does it carry out its digestive function?

A

Synthesized in the liver, stored in the gallbladder and serves its function in the duodenum

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196
Q

What are some functions of the liver?

A

Processes nutrients (esp. glycogenesis and gluconeogenesis), storage and mobilization of fats, activates/inactivates medications, produces bile, synthesizes albumin and clotting factors

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197
Q

What are the two circulatory vessels in a villus and what biomolecules are absorbed in each?

A

Capillaries (absorb water-soluble nutrients), lacetals (absorb fat-soluble molecules)

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198
Q

Which two organs digest proteins?

A

Stomach and small intestine

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199
Q

What would an elevated bilirubin level cause?

A

Blockage to bile flow, increased production of bilirubin (from massive hemoglobin release), or an inability of the liver to produce bile

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200
Q

Starch is hydrolyzed into maltose by enzymes from the:

A

Salivary glands and pancreas (salivary amylase and pancreatic amylase)

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201
Q

Which compounds do not pass through the liver before reaching the right heart

A

Fat-soluble compounds

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202
Q

List the vessels in the renal vascular pathway, starting from the renal artery and ending in the renal vein

A

Renal artery -> afferent arteriole -> glomerulus -> efferent arteriole -> vasa recta -> renal vein

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203
Q

What arm of the nervous system is responsible for contraction of the detrusor muscle?

A

Parasympathetic

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204
Q

What occurs in filtration?

A

Movement of solutes from blood into filtrate at Bowman’s capsule

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205
Q

What occurs in secretion?

A

Movement of solutes from blood into filtrate anywhere besides Bowman’s capsule

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206
Q

What occurs in reabsorption?

A

Movement of solutes from filtrate into blood

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207
Q

What is the predominant cell type in the epidermis?

A

Keratinocytes

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208
Q

What are the layers of the epidermis, from superficial to deep?

A

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale (Come, Let’s Get Sun Burned) - lucidum is not found everywhere in the epidermis

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209
Q

What are the layers of the dermis, from superficial to deep?

A

Papillary layer, reticular layer

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210
Q

What are some mechanisms the body uses to cool itself/retain heat?

A

Cooling = sweating vasodilation, retain heat = vasoconstriction, piloerection, shivering

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211
Q

In which of the following segments of the nephron is sodium NOT actively transported out of the nephron?

A

Thin portion of the ascending limb of the loop of Henle

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212
Q

In the nephron, amino acids enter the vasa recta (blood vessels in kidney) via the process of:

A

reabsorption

213
Q

Under normal physiologal circumstances, the primary function of the nephron is to create urine that is:

A

Hypertonic to the blood

214
Q

A laceration cuts down into a layer of loose connective tissue in the skin. Which layer of the skin is this?

A

Papillary layer

215
Q

When the pH of the blood is high, which substance is likely to be excreted in larger quantities in the urine?

A

Bicarbonate ions

216
Q

A drug is used that prevents the conversion of angiotensin I to angiotensin II. What is a likely effect of this drug?

A

Increased potassium reabsorption

217
Q

If a drug caused excessive buildup of acetylcholine in all synapses where it is the neurotransmitter, what symptoms would arise?

A

Increased urination and increased sweating

218
Q

What is GLUT2?

A

Important in liver and pancreas, Km = high (15 mM), is not saturated at normal glucose levels, is not responsive to insulin (can serve as glucose sensor)

219
Q

What is GLUT4?

A

Important in adipose tissue and muscle, Km = low (5 mM), is saturated at normal glucose levels, is responsive to insulin

220
Q

What is hexokinase?

A

Phosphorylates glucose to form glucose-6-phosphate, trapping glucose in the cell (inhibited by glucose-6-phosphate), IRREVERSIBLE

221
Q

What is glucokinase?

A

Phosphorylates and “traps” glucose in liver and pancreatic cells, and works with GLUT2 as part of the glucose sensor in B-islet cells (induced by insulin), IRREVERSIBLE

222
Q

What is PFK-1?

A

Catalyzes the rate-limiting step of glycolysis, phosphorylating fructose-6-phosphate to fructose 1,6-bisphophate using ATP (inhibited by ATP, citrate, and glucagon; activated by AMP, fructose 2,6-bisphosphate, and insulin), IRREVERSIBLE

223
Q

What is glyceraldehyde-3-phosphate dehydrogenase?

A

Generates NADH while phosphorylating glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate (REVERSIBLE)

224
Q

What is 3-phosphoglycerate kinase?

A

Performs a substrate-level phosphorylation, transferring a phosphate from 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate (REVERSIBLE)

225
Q

What is pyruvate kinase?

A

Performs another substrate-level phosphorylation, transferring a phosphate from phosphoenolpyruvate to ADP, forming ATP and pyruvate (activated by fructose 1,6-bisphosphate), IRREVERSIBLE

226
Q

Why must pyruvate undergo fermentation for glycolysis to continue?

A

Fermentation must occur to regenerate NAD+, which is in limited supply in cells. Fermentation generates no ATP or energy carriers; it merely regenerates the coenzymes needed in glycolysis

227
Q

Why is it necessary that fetal hemoglobin does not bind 2,3-BPG?

A

The binding of 2,3-BPG decreases hemoglobin’s affinity for oxygen. Fetal hemoglobin must be able to “steal” oxygen from maternal hemoglobin at the placental interface; therefore, it would be disadvantageous to lower its affinity for oxygen

228
Q

Which enzyme is responsible for trapping galactose in the cell? What enzyme in galactose metabolism results in a product that can feed directly into glycolysis, linking the two pathways?

A

Galactose is phosphorylated by galactokinase, trapping it in the cell. Galactose-1-phosphate uridyltransferase produces glucose 1-phosphate, a glycolytic intermediate; thus linking the pathways

229
Q

Which enzyme is responsible for trapping fructose in the cell? What enzyme in fructose metabolism results in a product that can feed directly into glycolysis, linking the two pathways?

A

Fructose is phosphorylated by fructokinase, trapping it in the cell (with a small contribution from hexokinase). Aldolase B produces dihydroxyacetone phosphate (DHAP) and glyceraldehyde (which can be phosphorylated to form glyceraldehyde-3-phosphate), which are glycolytic intermediates, thus linking the pathways

230
Q

What are the reactants and products of the pyruvate dehydrogenase complex?

A

Reactants = Pyruvate, NAD+ and CoA, Products = Acetyl-CoA, NADH, CO2

231
Q

How does acetyl-CoA affect PDH complex activity?

A

Acetyl CoA inhibits the PDH complex (pyruvate can then be used to form other products, such as oxaloacetate for use in gluconeogenesis)

232
Q

Under what physiological conditions should the body carry out gluconeogenesis?

A

When an individual has been fasting for over 12 hours. To carry out gluconeogenesis, hepatic (and renal) cells must have enough energy to drive the process of glucose creation, which requires sufficient fat stores to undergo B-oxidation.

233
Q

What are the four enzymes unique to gluconeogenesis?

A

Pyruvate carboxylase (replaces pyruvate kinase), phosphoenolpyruvate carboxylase (replaces pyruvate kinase), fructose-1,6-bisphosphatase (phosphofructokinse-1), and glucose-6-phosphatase (replaces glucokinase)

234
Q

How does acetyl-CoA shift the metabolism of pyruvate?

A

Inhibits pyruvate dehydrogenase complex while activating pyruvate carboxylase (shift: burning pyruvate in citric acid cycle -> creating new glucose molecules for the rest of the body)

235
Q

Given that a glycogen storage disorder affects the last enzyme of gluconeogenesis, predict the associated metabolic derangement that occurs.

A

Last enzyme in gluconeogenesis is glucose-6-phosphatase, so patients are unable to perform gluconeogenesis and glycogenolysis (unable to produce glucose during periods of fasting), resulting in a buildup of intermediates

236
Q

What are three primary functions of NADPH?

A

Lipid biosynthesis, bactericidal bleach formation in certain white blood cells, and maintenance of glutathione stores to protect against reactive oxygen species

237
Q

A man collapses while running a marathon and is taken to the emergency room. His blood is found to be somewhat acidic, and further tests show increased lactate dehydrogenase activity. This enzyme is involved in which of the following pathways?

A

Anaerobic glycolysis

238
Q

Which of the following organs does NOT require a constant supply of glucose from the blood for energy during a fast?

A

Liver

239
Q

When fatty acid B-oxidation predominates in the liver, mitochondrial pyruvate is most likely to be:

A

Carboxylated to oxaloacetate for entry into gluconeogenesis

240
Q

A biopsy is done on a child with an enlarged liver and shows accumulation of glycogen granules with single glucose residues remaining at the branch points near the periphery of the granule. The most likely genetic defect is in the gene encoding:

A

a-1,6 glucosidase (part of debranching enzyme complex)

241
Q

An investigator is measuring the activity of various enzymes involved in reactions of intermediary metabolism. One of the enzymes has greatly decreased activity compared to reference values. The buffer of the assay contains citrate. Which of the following enzymes would most likely be directly affected by the use of citrate?

A

Phosphofructokinase-1 (no citrate -> slows citric acid cycle -> negatively affect PFK)

242
Q

A man is given antibiotics to treat a urinary tract infection and develops an episode of red blood cell lysis. Further studies show weakness of the plasma membrane and Heinz bodies (collections of oxidized hemoglobin). Which of the following enzymes is most likely defective in this patient?

A

Glucose-6-phosphate dehydrogenase (stress on pentose phosphate pathway)

243
Q

After an overnight fast, which of the following processes would be expected to occur at an elevated rate compared with the well-fed state?

A

Glycogenolysis (would need to break down glycogen if you haven’t been eating)

244
Q

What is the overall reaction of the pyruvate dehydrogenase complex?

A

Pyruvate + CoA-SH + NAD+ -> acetyl-CoA + CO2 + NADH + H+

245
Q

What other molecules can be used to make acetyl-CoA, and how does the body perform this conversion for each?

A

Fatty acids, ketogenic amino acids, ketones and alcohols

246
Q

What is the purpose of all the reactions that collectively make up the citric acid cycle?

A

Complete oxidation of carbons in intermediates to CO2, forming energy carriers such as NADH and FADH2 for the ETC

247
Q

What enzyme catalyzes the rate-limiting step of the citric acid cycle?

A

Isocitrate dehydrogenase

248
Q

What are the three main sites of regulation within the citric acid cycle? What molecules inhibit and activate the three main check points?

A

Citrate synthase (inhibitors: ATP, NADH, succinyl-CoA, citrate), isocitrate dehydrogenase (inhibitors: ATP, NADH; activators: ADP, NAD+), alpha-ketogluterate complex (inhibitors: ATP, NADH, succinyl-CoA; activators: ADP, Ca2+)

249
Q

Which complexes are associated with pumping a proton into the intermembrane space, acquiring electrons from NADH, acquiring electrons from FADH2, and having the highest reduction potential?

A

Pumping proton into intermembrane space = complex 1,2,4; acquiring electrons from NADH = complex 1; acquiring electrons from FADH2 = complex 2; highest reduction potential potential = complex 4

250
Q

What role does the electron transport chain play in the generation of ATP?

A

Generates the proton-motive force, an electrochemical gradient across the inner mitochondrial membrane, which provides the energy for ATP synthase to function

251
Q

Based on its needs, which of the two shuttle mechanisms is cardiac muscle most likely to utilize? Why?

A

Malate-aspartate shuttle (more efficient shuttle, makes sense to use it to maximize ATP yield)

252
Q

What is the difference between the ETC and oxidative phosphorylation?

A

ETC = physical set of intermembrane proteins located on the inner mitochondrial matrix, and they undergo oxidation-reduction reactions as they transfer electrons to oxygen, the final electron acceptor (as electrons are transferred, a proton-motive force is generated in the intermembrane space); OXPHOS = the process by which ATP is generated via harnessing the proton gradient, and it utilizes ATP synthase to do so

253
Q

The delta G of NADH reducing oxygen directly is significantly greater than any individual step along the electron transport chain. If this is the case, why does transferring electrons along the ETC generate more ATP than direct reduction of oxygen by NADH?

A

By splitting up electron transfer into several complexes, enough energy is released to facilitate the creation of a proton gradient at many locations (greater proton gradient = greater ATP generation)

254
Q

During a myocardial infarction, the oxygen supply to an area of the heart is dramatically reduced, forcing the cardiac myocytes to switch to anaerobic metabolism. Under these conditions, which of the following enzymes would be activated by increased levels of intracellular AMP?

A

Phosphofructokinase-1

255
Q

A patient has been exposed to a toxic compound that increases the permeability of mitochondrial membranes to proteins. Which of the following metabolic changes would be expected in this patient?

A

Increased oxygen utilization

256
Q

Where does the citric acid cycle take place?

A

Mitchondrial matrix

257
Q

Fatty acids enter the catabolic pathway in the form of:

A

Acetyl-CoA

258
Q

In which part of the cell is cytochrome c located?

A

Inner mitochondrial membrane

259
Q

How much ATP is produced from NADH and FADH2?

A

NADH = 2.5; FADH2 = 1.5

260
Q

Why is it preferable to cleave thioester links rather than typical ester links in aerobic metabolism?

A

Thioester hydrolysis has a higher energy yield

261
Q

Which of the following best explains why cytosolic NADH can yield potentially less ATP than mitchondrial NADH?

A

Electron transfer from cytosol to matrix can take more than one pathway

262
Q

Which complex does NOT contribute to the proton-motive force?

A

Complex 2

263
Q

What is the most likely reason the body stores the bulk of its calories in the form of triglycerides and not glycogen?

A

Glycogen storage requires a significant amount of water (polar, hydrophilic) while triglyceride storage does not (nonpolar, hydrophobic)

264
Q

Why is the activity of lactate dehydrogenase necessary for long-term glycolysis under anaerobic conditions?

A

Cells have a limited pool of NAD+ that must be replenished for glycolysis to continue indefinitely

265
Q

In a fasting state:

A

Cells use beta-oxidation of fatty acids for energy, yields acetyl-CoA which is used to form ketone bodies via ketogenesis

266
Q

What helps maintain flexibility in cell membranes through interactions with the phospholipid fatty acid chains?

A

Cholesterol

267
Q

When a cell is at Nernst equilibrium for a specific ion, this means that:

A

The force due to electric potential is balanced by the force due to the concentration gradient of that ion

268
Q

Where is glucose normally absorbed in the kidney?

A

Proximal convoluted tubule

269
Q

What does acetylcholine stimulate?

A

Sweat glands, attention, arousal (not sympathetic NS)

270
Q

What is chemiosmosis?

A

The hydrogen ions passing through the special channels in ATP synthase and causing it to turn, forming ATP

271
Q

What is oxidative phosphorylation?

A

Phosphorylation = ADP + P -> ATP, oxidative = phosphorylation is happening because of oxidation of all of these enzymes, including NADH

272
Q

What does carbonic anhydrase do?

A

Assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions

273
Q

In what environment does a disulfide bridge occur?

A

An oxidizing environment

274
Q

How does temperature, pH, chemicals, and enzymes affect protein structure?

A

Temperature denatures 2”, 3”, 4” structure; pH denatures 3”, 4”; chemicals denatures 2”, 3”, 4”; enzymes denatures 1”

275
Q

What is the difference between agarose gel and SDS gel electrophoresis?

A

SDS = small molecules; agarose = big molecules

276
Q

What is the equation for catalytic efficiency?

A

kcat/Km

277
Q

What is the impact of a competitive inhibitor?

A

Bind to active site (Increase Km, no change in Vmax)

278
Q

What is the impact of a noncompetitive inhibitor?

A

Bind to allosteric site (unchanged Km, decreased Vmax)

279
Q

What is the impact of an uncompetitive inhibitor?

A

Bind to E-S complex (decrease Km, decrease Vmax)

280
Q

What is the difference between denaturation and hybridization?

A

Denaturation = splitting apart the two strands of DNA; hybridization = putting 2 strands of DNA together

281
Q

What does topoisomerase do?

A

Prevent supercoiling (uncoils)

282
Q

How to remember DNA polymerase I vs DNA polymerase III?

A

DNA poly I = removes RNA primer; DNA poly III = can draw an x in the middle of the III (EXOnuclease activity, proofreads and replicates)

283
Q

What does degenerate mean?

A

Many codons code for the same AA

284
Q

What does snRNPs and snRNAs form?

A

The spliceosome, completes transesterification reaction to remove introns and ligate exons

285
Q

What are some non-coding RNAs?

A

miRNA (gene silencing), rRNA, tRNA, snoRNA, snRNA

286
Q

What is the difference between a point mutation and a missense mutation?

A

Point mutation = 1 AA replaced with another; missense mutation = any mutation that changes 1 AA to another

287
Q

What is senescence?

A

Dormant state where DNA does not divide anymore

288
Q

What are some post-transcriptional modifications?

A

5’ cap (protects from exonucleases); 3’-poly A tail (protects, promotes, regulates)

289
Q

What are nucleosomes?

A

Histones and DNA

290
Q

What is the hybridization technique?

A

Lyse cells, expose contents to well with fluorescent tag -> certain color -> gene expression up or down-regulated

291
Q

What are telomeres?

A

Ends of chromosomes, prevent them from deterioration (buffer zone = contain no important genes), prevent the chromosomes from sticking to each other (highly repetitive)

292
Q

What type of DNA is present in important genetic info?

A

Single copy (exons)

293
Q

What is DNA cloning?

A

Bacteria, plasmid + heat shock -> some bacteria will uptake the plasmid

294
Q

Where do crossovers occur in meiosis?

A

Prophase I, occurs at chiasma, causes variation

295
Q

What is the synaptonemal complex?

A

A protein structure that forms between homologous chromosomes during meiosis, mediates synapsis and recombination during meiosis I

296
Q

What is genetic drift?

A

Random changes in reproduction of the population (more likely with small populations)

297
Q

What is a polymorphism?

A

Different forms of alleles/traits

298
Q

What is the founder effect?

A

Organisms go and live in a new place, decrease in population

299
Q

What is a bottleneck?

A

Disaster -> massive reduction in population -> big example of genetic drift

300
Q

What is allopatric vs. sympatric speciation?

A

Allopatric = geographic speciation; sympatric = reproductive isolation within the population

301
Q

Why is the pentose phosphate pathway called the pentose phosphate pathway?

A

Pentose = 5-carbon sugar; phosphate = phosphorylated molecule -> NADPH (no ATP formed/used, uses glucose-6-phosphate)

302
Q

How are fats digested, mobilized, and transported?

A

Lipases in small intestine breaks down fats -> FAs broken down in TAGs -> lipoproteins package hydrophobic moleculess into the core of a protein molecule (chylomicrons produced) -> lipoprotein lipase breaks down into free FAs and glycerol (stimulated by insulin), adipose cells store fat (hormone sensitive lipase break down FAs), everything except fats pass through liver, proteins/carbohydrates go into capillaries, fats go into lacteals (much larger pores) -> ducts -> veins -> drained in thoracic vein

303
Q

What are gap junctions?

A

Tunnel, let water/ions flow through (cardiac muscle)

304
Q

What are tight junctions?

A

Water tight seal (bladder, kidney, intestine)

305
Q

What are desmosomes?

A

Spot welds (skin, intestines)

306
Q

What is the nucleolus?

A

Inside the nucleus, made up of proteins and ribonucleic acids, function = transcribe rRNA

307
Q

What is the nuclear envelope/nuclear pores?

A

Nuclear envelope = a double membrane system (inner and outer membrane); nuclear pores = holes in nuclear envelope where things can pass in and out of the nucleus

308
Q

What are lysosomes?

A

Digest various molecules and substances (autophagy = “self eating”), crinophagy = digest excess secretory produt

309
Q

What is the smooth ER?

A

Synthesizes lipids, metabolizes carbs, detox drugs/other toxins

310
Q

What is the rough ER?

A

Site of protein synthesis, post-translational modifications

311
Q

What is the Golgi apparatus?

A

Modifies proteins that are made in the RER, sorts/sends proteins to proper destination, synthesis of macromolecules for secretion

312
Q

What are intermediate filaments?

A

Intermediate = between layers = structural support (resist mechanical stress), comparable to strings of a mattress

313
Q

What are microtubules?

A

Alpha-tubulin and beta-tubulin form a dimer, minus end anchored to MTOC (centrosome = 9 triplets of microtubules; cilia and flagella = 9 + 2 rule), form network from soma to synaptic terminal

314
Q

What are cilia and flagella?

A

Cilia = hair-like coverings, push mucus into respiratory tract; flagella = tail-like projections, help cells move (dynein help cilia and flagella move)

315
Q

What is the permeability of the inner and outer membrane of the mitochondria?

A

Outer membrane = lipid bilayer = permeable to small molecules; inner membrane = not permeable, have cristae to increase SA for cellular respiration

316
Q

What are viroids?

A

Circular DNA (found in plants, catalytic RNA => self-cleave to create more viroids) - SMALL INFECTIOUS PATHOGENS

317
Q

What are prions?

A

Infectious proteins; changes alpha helices to beta sheets

318
Q

What is the difference between enveloped and non-enveloped virus?

A

Enveloped = directly fuses with the membrane ; non-enveloped = trick receptor into letting them in

319
Q

How does viral replication occur?

A

1) Get inside cell, 2) Takes over cell’s machinery and self-assemble (lytic cycle), 3) combine with host’s genetic information with there are not many hosts (lysogenic cycle)

320
Q

What is chemotaxis?

A

Sensing chemicals and moving towards/away from it

321
Q

What is the process of spermatogenesis?

A

Spermatogonium -> primary spermatocyte -> 2 secondary spermatocytes -> 2 spermatids for each secondary spermatocyte -> spermatozoa

322
Q

What makes sperm/testosterone?

A

Seminiferous tubules make sperm (Sertoli cells nourish the sperm); cells of Leydig make testosterone

323
Q

What is fertilization?

A

Sperm fertilizing egg, then called a zygote

324
Q

What is cleavage?

A

Splitting without growth (in zona pellucida)

325
Q

Describe after cleavage to gastrulation.

A

After cleavage, forms a morula -> differentiation (trophoblasts and embryoblasts) -> inner cell mass and blastocoel (blastocyst) -> lose zone pellucida and gain amniotic cavity -> form epiblasts/hypoblasts, bilaminar disk, primitive streak -> gastrulation

326
Q

What is gastrulation?

A

Forming primary germ layers (mesoderm forms notochord, induces a change in ectoderm -> neural plate becomes neural tube, neural crest cells form, give rise to ectoderm)

327
Q

What part of the antibody recognizes the antigen?

A

The variable region of the heavy and light chains

328
Q

MHC I molecules display antigens derived from which type of pathogen?

A

Viruses (MHC II = bacteria)

329
Q

A patient requiring a blood transfusion is discovered to have type AB- negative blood. Which donor blood types can they accept?

A

B-, A-, AB-, and O-

330
Q

Which immunoglobulin can cross the placenta?

A

IgG

331
Q

Which immunoglobulin is involved in the allergy response?

A

IgE

332
Q

There are two types of alvelolar cells that line the alveolar sacs in the lungs. Type I cells participate in gas exchange. What do type II cells do?

A

They secrete surfactant, a chemical that helps the alveoli stay open

333
Q

What are the directions of vesicle traffic in the cell?

A

ER -> Golgi, Golgi -> ER

334
Q

How are mitochondria semi-autonomous?

A

They contain some of their own genes and replicate independently of the nucleus via binary fission

335
Q

Where is the electron transport chain located in prokaryotic cells?

A

Plasma membrane

336
Q

A virologist wants to determine if the position of a penicillin resistance gene is close to the origin of replication of her plasmid. She initiates conjugation with bacteria that contain the plasmid with recipient bacteria. What can she do to determine the gene’s location?

A

Disrupt the conjugation at different times. Then, determine the proportion of penicillin resistant bacteria in the coculture.

337
Q

The formation of prions can be described as a malfunctioning of what process?

A

Post-translational modification

338
Q

During early development, an embryo contains an accessible genome and expresses many of the proteins coded for in the genome. Which organelle most likely contributes to this activity?

A

Nucleolus (synthesizes rRNA)

339
Q

The synthesis of progesterone most directly relies upon which organelle?

A

Smooth ER

340
Q

Which of the following domains of life utilizes histones to wrap DNA and is noted for its unique ability to utilize alternative sources of energy such as sulfur and ammonia?

A

Archaea

341
Q

Based on structure and genome, which of the following most closely resembles mitochondria?

A

Gram-negative bacteria

342
Q

A virologist wants to modify her virus so that it can infect more cell types. Which of the following viral genes should she change?

A

Tail fibers

343
Q

What are meissner corpuscles?

A

Rapidly-adapting, encapsulated neurons that responds to low-frequency vibrations and fine touch; they are located in the glabrous skin on fingertips and eyelids

344
Q

What are pacinian corpuscles?

A

Rapidly-adapting, deep receptors that respond to deep pressure and high-frequency vibration

345
Q

What are merkel cells?

A

Slow-adapting, unencapsulated nerve endings that respond to light touch; they are present in the upper layers of skin that has hair or is glabrous

346
Q

What are ruffini endings?

A

Slow adapting, encapsulated receptors that respond to skin stretch and are present in both the glabrous and hairy skin

347
Q

When you exercise, what is the result on the hemoglobin-oxygen curve?

A

Decreased pH, increased temperature, increased BP-2,3G, increased amount of carbon dioxide (decreased affinity of Hb to O2)

348
Q

Catecholamines are:

A

Hormones and neurotransmitters

349
Q

The stereochemical designations alpha and beta distinguish between:

A

Epimers at an anomeric carbon atom

350
Q

Which event is directly mediated by a ligand-gated ion channel?

A

Influx of Na+ across the motor end plate resulting in the depolarization of the muscle fiber membrane (when Na+ ion channels bind the ligand acetylcholine)

351
Q

What happens in a Southern blot?

A

Uses a restriction digest to differentiate between mutant and wild-type alleles (mutation should create or eliminate a restriction site, most of which are palindromic sequences of 4-6 base pairs

352
Q

What is the average molecular weight of an amino acid?

A

110 Da

353
Q

If an enzyme has a Hill coefficient that is ~ 1, what does that mean?

A

Negative cooperativity

354
Q

For isoelectric focusing to work:

A

A stable pH gradient must be established in the gel

355
Q

Kd is:

A

Dissociation constant (higher affinity = lower Kd)

356
Q

What are signal sequence domains?

A

Protein domains required for proteins that are directed toward secretory pathways

357
Q

What element differs between different cells in an organism?

A

Nuclear factors (a type of transcription factors)

358
Q

How many molecules of reduced electron carrier are generated during conversion of α-ketoglutarate to oxaloacetate in the citric acid cycle?

A

Three (2 NADH and 1 FADH2) - NADH is made during alpha-ketogluterate dehydrogenase, isocitrate dehydrogenase, and malate dehydrogenase; FADH2 is made during fumarase

359
Q

RNA polymerase is not used in:

A

cDNA cloning

360
Q

When glucagon binds to its receptor:

A

It activates its coupled G protein, activities of the adenylate cyclase, protein kinase A and cAMP are increased

361
Q

Infusion of glucagon will result in:

A

Mobilization of endogenous glucose storage thereby preventing hypoglycemia and brain injury

362
Q

In the pentose phosphate way, which enzyme catalyzes the production of 6-phosphogluconolactone?

A

Glucose 6-phosphate dehydrogenase

363
Q

For a respiratory quotient:

A

0.7 = lipids, 0.8-0.9 = amino acids, 1 = carbohydrates

364
Q

What is convergent evolution and divergent evolution?

A

Convergent evolution = different lineage, evolving closer together to be similar (ex. dolphin and shark); divergent evolution = same lineage, evolving apart to be more different (ex. bats and horses)

365
Q

Beta-OHB is a component of:

A

Ketone bodies

366
Q

The adrenal medulla is part of which branches of the peripheral nervous system?

A

The sympathetic branch of the autonomic nervous system only

367
Q

Why are tubulin levels measured in a Western Blot?

A

Tubulin is used as a control to assess the total protein level in different samples

368
Q

What does CoQ 10 do in the electron transport chain?

A

It brings electrons from Complex II to Complex III

369
Q

Certain viruses contain RNA as their genetic material. One of the ways these RNA viruses replicate themselves is to:

A

Code for or carry a transcriptase that copies viral RNA

370
Q

Based on the passage, which of the following conditions most likely contributed to the boy’s weight loss?

A

A decrease in the surface area of the small intestine, leading to a decrease in nutrient absorption

371
Q

Within the intestines, unabsorbed fats are broken down into fatty acids by intestinal bacteria. Given this, excess unabsorbed fats most likely have which of the following effects within the intestines?

A

They increase the osmotic pressure within the intestines, leading to diarrhea

372
Q

The normal path of sperm movement from the male testis to the point of fertilization in the female is:

A

Epididymis, vas deferens, urethra, vagina, cervix, uterus, fallopian tube

373
Q

Albumin is the major blood osmoregulatory protein. The most likely effect of a sharp rise in the level of serum albumin is:

A

An influx of interstitial fluid into the bloodstream

374
Q

If chromosomal duplication before tetrad formation occurred twice during spermatogenesis, while the other steps of meiosis proceeded normally, which of the following would result from a single spermatocyte?

A

Four diploid sperm

375
Q

In the human “knee-jerk” reflex, the knee is struck and the lower leg jerks forward. Which of the following represents the complete pathway that the nerve impulse travels in effecting this response?

A

Sensory neuron, motor neuron (simple monosynaptic stretch reflex)

376
Q

Synthesis of antibody proteins in eukaryotic cells is associated with what organelle?

A

ER (Rough ER)

377
Q

Rates of endocytosis vary from cell type to cell type. What cell would be predicted to have the highest rate of endocytosis?

A

Macrophage

378
Q

What comprises the mineral component of human bone?

A

Hydroxyapatite (Ca10[PO4]6[OH]2)

379
Q

How many molecules of NADH are produced from six molecules of glucose that undergo glycolysis?

A

12

380
Q

Which combination of lipid type and temperature results in the most disordered membrane?

A

Lipids with unsaturated acyl chains at high temperature

381
Q

Which event occurs when a G protein-coupled receptor is activated?

A

The α subunit binds GTP

382
Q

What does caspase activation do?

A

Leads to apoptosis

383
Q

Between lysine and arginine, which one is more basic?

A

Arginine

384
Q

Specific activity is a measure of:

A

The enzyme units per milligram of total protein in a solution

385
Q

Researchers noted that in the absence of a reducing agent the elution time of a certain protein from a size-exclusion column decreased considerably relative to the elution time when the buffer contained a reducing agent. Which type of molecular interaction was responsible for this observation?

A

Disulfide bonding

386
Q

The transition of which amino acid from the interior of a soluble globular protein to the surface is associated with the largest positive ΔGº?

A

Phenylalanine

387
Q

Disruption of two disulfide bonds within a protein requires:

A

2 molecules of NADH

388
Q

Cyanogen bromide cleaves peptide bonds by first undergoing nucleophilic attack by the side chain of a methionine residue. Which atom is the nucleophile in this reaction?

A

Sulfur

389
Q

What are some functions of binding proteins?

A

Regulation of gene transcription, sequestration of solutes, transport of substances that are insoluble in water

390
Q

In the menstruation cycle of a healthy adult female as:

A

Estogen levels rise, the endometrium thickness increases

391
Q

A woman takes a pregnancy test measuring human chorionic gonadotropin (hCG) levels. The test result comes back negative. However, she is in her sixteenth week of pregnancy. Which of the following explains the false-negative result?

A

By the second trimester, the placenta secretes high amounts of estrogen and progesterone

392
Q

Which of the following inherited disorders can result from malfunctioning microtubules?

A

Down’s Syndrome

393
Q

What role does estrogen play in the menstrual cycle?

A

Regrowth and vascularization of the endometrial lining

394
Q

What is true about ovulation?

A

It is preceded by a rise in estrogen during the follicular phase, which is characterized by regrowth of the endometrium

395
Q

In a healthy female, the corpus luteum:

A

Is functionally replaced by the placenta after the first trimester

396
Q

When is the first meiotic division of oogenesis completed, forming the secondary oocyte?

A

Shortly before ovulation

397
Q

At the end of his initial hospital stay, a few E. coli cells remained in the patient’s colon, even though he was taking antibiotics. These cells were most likely present because:

A

Chance mutations in a few E. coli before the treatment made these cells and their descendants antibiotic-resistant

398
Q

The patient’s ruptured appendix required treatment with antibiotics because he had a bacterial infection caused by:

A

E. coli entering the abdominal cavity from the appendix

399
Q

Assuming that the vertebrates were all of comparable size, which of the following vertebrates would be expected to have the strongest and heaviest bones?

A

A land-dwelling mammal

400
Q

In eukaryotes, oxidative phosphorylation occurs in the mitochondrion. The analogous structure used by bacteria to carry out oxidative phosphorylation is the:

A

Plasma membrane

401
Q

What are some of the processes controlled by the sympathetic nervous system?

A

Peristalsis, secretion of digestive enzymes, nutrient delivery to muscles and organs

402
Q

The amount of NE released by sympathetic nerve terminals will be most strongly influenced by a change in which of the following?

A

Extracellular Ca2+

403
Q

The osmotic concentration of plasma proteins in the venous side of capillaries helps reduce the amount of interstitial fluid in tissues by inducing:

A

Passive H2O diffusion along a concentration gradient

404
Q

Capillaries in the kidney and elsewhere in the body maintain fluid homeostasis by balancing hydrostatic and osmotic pressures. Which of the following is the initial effect of a blood clot forming on the venous side of a capillary bed?

A

Net fluid flow in the direction of interstitial spaces will increase

405
Q

Radioactively labeled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?

A

Ribosomes

406
Q

What occurs during normal inspiration of air in mammals?

A

Elevation of rib cage, contraction of diaphragm, reduction of pressure in the pleural cavity, contration of external intercostal muscles

407
Q

The parasympathetic nerves to the iris release acetylcholine onto the circular muscles causing:

A

Pupillary constriction

408
Q

Rapid removal of acetylcholine from the circualtion would inactivate parasympathetic:

A

Stimulation of digestive secretion consonant with rapid arousal of the animal in an emergency

409
Q

The autonomic nerve fibers that directly innervate the heart to cause cardiac slowing are:

A

Parasympathetic motor fibers

410
Q

In terms of size, viruses are:

A

Smaller than all known eukaryotic cells

411
Q

What type of media should be used to grow virions in the laboratory?

A

A tissue culture (viruses need intact host-cells, aka NOT non-cellular media)

412
Q

A microbe pathogen was hypothesized as the causative agent of the disease described in the passage because:

A

The disease was infectious

413
Q

Hybridization requires:

A

Base pairing between complementary nucleic acid sequences

414
Q

In human females, mitotic divisions of oogonia that lead to formation of presumptive egg cells (primary oocytes) occur between:

A

Fertilization and birth only

415
Q

Which tissues have cells that are in direct contact with the external environment or elements of the external environment?

A

The lining of the reproductive tract, respiratory tract, and gastrointestinal tract

416
Q

Between the heart, arteries, arterioles, and capillaries, which one would have the lowest pressure?

A

Capillaries

417
Q

What is the equation for blood flow?

A

Pressure = cardiac output x vascular resistance

418
Q

Enhanced activity of which muscles would cause vasoconstriction?

A

Smooth muscle (leads to hypertension)

419
Q

What is a primary process of the colon?

A

Water absorption

420
Q

An ulcer that penetrated the wall of the intestine would allow the contents of the gastrointestinal tract to enter:

A

The peritoneal cavity

421
Q

What is the pleural cavity?

A

The space that lies between the pleura, the two thin membrane that line and surround the lungs

422
Q

What is the perineum?

A

The area between the anus and the scrotum or vulva

423
Q

The finches observed by Darwin on the Galapagos Islands are an example of adaptive radiation. In order to set up conditions that would produce adaptive radiation, it would be necessary to place members of:

A

One species in several different environments (adaptive radiation = the divergence of one species into multiple species over time)

424
Q

Postmenopausal women receiving estrogen and progesterone therapy will most likely experience which of the following side effects?

A

Periodic menstruation will resume

425
Q

The cell type in the male reproductive system that is most analogous to the female ovum is the:

A

Spermatozoon

426
Q

What correctly describes the distinction between the exocrine and endocrine portions of the testis?

A

The exocrine portion releases its products into ducts; the endocrine portion releases its products into the blood

427
Q

A drug that binds to tubulin molecules of plant cells and prevents the cells from assembling spindle microtubules would most likely cause the resulting plants or plant cells to have:

A

More than 2 sets of chromosomes

428
Q

Where does transcription occur in prokaryotic cells?

A

Cytoplasm

429
Q

Cancer cells most likely have an abnormality in their:

A

DNA

430
Q

Fever in septic shock leads to which of the following compensation mechanisms?

A

Dilation of capillary beds in the skin

431
Q

Pulmonary arterial blood differs from the aortic blood because it has:

A

Less O2, more CO2, and lower pH

432
Q

In comparison with the wall of the right ventricle of the heart, the left ventricular wall is:

A

Thicker and generates a higher pressure when it contracts (right = lungs; left = rest of body)

433
Q

If an artery that supplies blood to a lung lobe was blocked but ventilation to the lobe was unaffected, how would alveolar gas partial pressures change?

A

PO2 would increase and PCO2 would decrease

434
Q

A characteristic common to arteries, veins, and capillaries is the:

A

Presence of a layer of endothelial cells

435
Q

The pancreas produces which of the following substances for the digestive system?

A

Proteolytic enzymes

436
Q

Enzymes do not affect:

A

Keq values

437
Q

Transferrins are an important class of mammalian glycoproteins that transport iron from the blood into appropriate cells. Once an iron-transferrin complex forms, it is recognized by a receptor and endocytosed into a gradually-acidified endosome. Which of the following most likely represents the affinity of a transferrin for its iron ligand?

A

High at extracellular pH, but decreasing as pH decreases

438
Q

When a signal molecule arrives at a G protein coupled receptor, the G protein:

A

Becomes activated

439
Q

What would bind to a ligand-gated ion channel?

A

Serotonin, GABA, Glycine

440
Q

Most cytochrome P450 enzymes alter the activity of drugs by:

A

Oxidizing them

441
Q

A defining characteristic of proteins that act as transcription factors (such as STAT5b) is that they:

A

Contain a DNA binding domain

442
Q

As blood passes through actively contracting skeletal muscle tissue, the affinity of hemoglobin for oxygen in the muscle tissue:

A

Decreases as a result of a decrease in plasma pH

443
Q

What is Henry’s law?

A

Relates the solubility of a gas to the pressure of the gas above the solution

444
Q

If a question is talking about transcriptional regulation:

A

It is probably measuring mRNA levels (good to use RT-PCR)

445
Q

A peptide consisting of nine amino acids was partially hydrolysed. Three different tripeptides were isolated. None of the tripeptides share a common amino acid. Based on the data, what is the total number of possible structures possible for the full-length peptide?

A

6

446
Q

What describes the inactive X chromosome in mammalian females?

A

It is one of the last chromosomes to replicate

447
Q

When more bile is released:

A

The muscle in the wall of the gallbladder contracts and the hepatopancreatic sphincter relaxes

448
Q

On the day of the experiment, the subjects drank about 1 L of water on average and excreted about 400 mL of urine. The most likely explanation for the difference between water intake and urine excretion is that:

A

Water was excreted via the skin and the lungs

449
Q

The osmolarity of urine in these subjects was 958 milliosmoles/L, compared with an average blood osmolarity of 284 milliosmoles/L. The higher osmolarity of urine suggests that:

A

The kidneys are acting to conserve water

450
Q

Which of the following responses could maintain cardiac output under dehydration conditions that reduce blood volume?

A

An increase in heart rate

451
Q

During exercise, the osmolarity of venous blood from active muscles will increase as a result of an increase in:

A

Lactate concentration in plasma.

452
Q

Which pathway depicts the sequence of cellular compartments traversed by newly synthesized GABA-receptor subunits as they move to the cell surface?

A

Rough endoplasmic reticulum, Golgi complex, and secretory transport vesicle

453
Q

Which process is most likely responsible for the failure of a gamete to receive a copy of a particular chromosome?

A

Non-disjunction

454
Q

How might the expression of telomerase in embryonic stem cells allow them to create more daughter cells in their lifetime?

A

The telomerase prevents crucial biosynthesis genes located near the telomere from being silenced

455
Q

A chemist makes a drug that should lead to rapid, direct degradation of its target protein. However, when the chemist performs a Western blot for the protein after treating cells with the drug, she only notices a small decrease in the amount of protein. Which of the following could explain the partial decrease?

A

The drug targets a region of the protein made by an exon that is alternatively spliced

456
Q

What is a difference between DNA and RNA?

A

RNA is more reactive than DNA

457
Q

Growth hormone:

A

Stimulates insulin-like growth factor 1 (IGF-1)

458
Q

In prokaryotic translation:

A

Initiation is facilitated by a Shine-Dalgarno sequence in the mRNA

459
Q

If the p value is less than 0.05:

A

One should reject the null hypothesis

460
Q

What is the normal fate of a tRNA molecule after delivering its amino acid to a ribosome?

A

The tRNA is recharged with a new amino acid by an aminoacyl-tRNA synthetase.

461
Q

What is a case-control study?

A

Subjects with a certain outcome are assessed for previous risk factors.

462
Q

A biologist suspects that she has found a new oncogene involved with melanoma growth. Which of the following results suggests that the oncogene is activated through an epigenetic mechanism?

A

The sequence of the exons of the oncogene in a cancer tissue sample perfectly matches the reference genome. A Western blot of the protein in a cancer sample yields a band that is thicker than the band seen in a healthy control sample

463
Q

Which of the following molecules is a direct product of beta-oxidation?

A

NADH (also FADH2 is)

464
Q

In times of glucose deprivation, the body can obtain energy by utilizing its stores of fat. This involves the production of ketone bodies, the metabolism of which is relatively inefficient. One particular ketone body can be detected by smelling one’s breath. Which product is responsible for yielding sweet-smelling breath and sweat?

A

Acetone

465
Q

A pharmaceutical compound targets and inhibits the carnitine shuttles used by cells. A human cell treated with this medication currently displays excess acetyl-CoA inside the mitochondria and insufficient cytosolic acetyl-CoA. What will be the most direct result of this circumstance?

A

Fatty acid synthesis (occurs in the cytosol)

466
Q

Urea is excreted as an end product of amino acid metabolism. From which molecule is urea derived, and how is that substance freed from amino acid residues?

A

Ammonia; it is generated when amino groups are removed via an aminotransferase.

467
Q

What is a nucleoside?

A

A five-carbon sugar attached to a nitrogenous base

468
Q

Thyroxine is a hormone produced by the thyroid in a reaction that uses a tyrosine substrate. This hormone affects virtually every cell in the body by binding to its cytosolic receptor and translocating into the nucleus. Compared to steroid hormones, thyroxine:

A

Differs in its tissue of origin, but shares a similar mechanism of action

469
Q

Proper eukaryotic DNA replication requires a number of enzymes. The elongation step of replication involves:

A

DNA polymerase

470
Q

Four distinct mRNA codons correspond to the amino acid valine. However, only a single tRNA molecule is able to add valine residues to a growing peptide chain. How is it possible that one anticodon can recognize multiple codons?

A

Anticodons can experience non-Watson-and-Crick base interactions known as wobble base pairings

471
Q

One advantage of the degeneracy of the genetic code is that:

A

It reduces the effect of point mutations because multiple codons may correspond to the same amino acid

472
Q

Which type of RNA is most active during post-transcriptional processing?

A

snRNA

473
Q

What does the poly-A tail do?

A

Prevents enzymatic degradation of the transcript

474
Q

Which of the following enzymes, structures, or processes is NOT required to produce a mature mRNA transcript?

A

A stop codon

475
Q

A certain protein release factor functions to specifically recognize stop codons and terminate translation. How many tRNA molecules bind to the same codons as this factor?

A

None

476
Q

What is the difference between connexin, cadherins, occludin, and fibronectin?

A

Fibronectin = bridging protein; connexin = gap junction protein; cadherins = cell-cell junctions; occludin = tight cell-cell juntions

477
Q

What are some examples of exocrine glands?

A

Liver, pancreas, salivary gland

478
Q

Injuries to cartilaginous tissue, such as torn and stretched ligaments, can often take quite some time to heal. Which statement best explains why injuries to this type of connective tissue heal so slowly?

A

Cartilage relies on diffusive rather than direct vascular delivery of nutrients, and repairing cells therefore have a hard time sustaining increased activity

479
Q

A congenital defect in the synthesis of the proteins cloudin and occludin is most likely to impact the function of the:

A

Intestinal lining

480
Q

The parasympathetic nervous system promotes vasodilation in which of the following areas?

A

Small intestine and stomach

481
Q

Which of the following neurons is most likely to fire an action potential?

A

An unmyelinated neuron that receives multiple EPSPs that summate temporally

482
Q

If the anterior pituitary were suddenly rendered incapable of producing hormones, which of the following compounds would be directly affected?

A

GH and LH

483
Q

A newly discovered biological factor is found to bind to a cytosolic nuclear receptor after entering the cell. Based on this observation, this molecule is likely which type of hormone?

A

Steroid hormone

484
Q

What organ synthesizes steroid hormones?

A

Adrenal cortex

485
Q

Oncotic pressure is mainly generated by serum albumin. How can this molecule best be described?

A

As a soluble 65-kd protein that serves to draw fluid into the venous ends of capillary beds

486
Q

In fluid dynamics, the continuity equation relates the cross-sectional area of a vessel to the speed of fluid moving through it. According to this equation:

A

Blood travels slower in capillaries than in arterioles

487
Q

Increased blood viscosity is a known contributor to the development of chronic hypertension. Which of the following is likely to increase blood viscosity?

A

Sickle-cell anemia

488
Q

Carbonic anhydrase catalyzes the conversion of water and carbon dioxide to carbonic acid. This process is a crucial part of the maintenance of a buffered blood pH. Which metal cofactor is necessary for carbonic anhydrase to function?

A

Zinc

489
Q

HIV infects and kills helper T cells. Which of the following cell types will function less effectively in a patient in the late stages of AIDS?

A

Macrophages, B cells, and cytotoxic T cells

490
Q

Some bacterial toxins are able to bind with high affinity to MHC, displacing whatever peptide was previously bound. As a result, the immune response is systemically activated without a clear target. The resulting pathology would most resemble:

A

Anaphylaxis

491
Q

How does mitotic prophase differ from prophase II of meiosis?

A

In prophase II, half of the number of chromosomes are present in comparison to prophase

492
Q

A low recombination frequency means:

A

The two genes being measured are physically close

493
Q

What might be a consequence of a dysfunctional synaptonemal complex?

A

During meiosis, problems might occur with recombination and synapsis

494
Q

What is sympatric speciation vs. allopatric speciation vs. parapatric speciation?

A

Allopatric = physical barrier; sympatric = no physical barrier; parapatric = two distinct populations overlap

495
Q

Which steps involved in the contraction of a skeletal muscle require binding and/or hydrolysis of ATP?

A

Dissociation of myosin head from actin filament, conformational change that moves actin and myosin filaments relative to one another, and reuptake of calcium into the sarcoplasm

496
Q

Platelets, endothelial cells, and mature RBCs are all:

A

Bone-marrow derived

497
Q

Lysine and amino acids with similar chemical characteristics in histones most likely promote the interaction of histones with which DNA components?

A

Phosphate groups

498
Q

The liver synthesizes factors that act cooperatively with platelets to facilitate which physiological process?

A

Blood clotting

499
Q

The amino acid precursor of serotonin is best described as having which type of R group?

A

Aromatic (tryptophan)

500
Q

Increasing the volume of air that reaches the alveoli and takes part in gas exchange will cause blood pH to:

A

Increase, because the partial pressure of CO2 in the blood will decrease

501
Q

What is the difference between cofactors, coenzymes, and vitamins?

A

Cofactors = catalysts; coenzymes = organic, carbon-based; carrier molecules (ex. NADH); vitamins = organic cofactors/coenzymes (ex. Mg2+, Ca)

502
Q

What is senescence?

A

A dormant state where DNA does not divide anymore

503
Q

What is the difference between DNA polymerase I and DNA polymerase III?

A

1: removes RNA primer @ end of replication; 3: replicates, proofreads (exonuclease activity)

504
Q

What is the difference between single copy, repetitive, and highly repetitive?

A

Single copy = most of organism’s important genetic info, low mutation rate; repetitive = found near centromere, higher mutation rate; highly repetitive = no genes, not transcribed/translated, ex. telomeres

505
Q

What is a synaptonemal complex?

A

A protein structure that forms between homologous chromosomes uring meiosis, mediates synapsis and recombination during meiosis I

506
Q

What does glycogen synthase do?

A

Takes UDP off and attaches glucose to glycogen, allows glycogenesis to occur

507
Q

What does glycogen phosphorylase do?

A

Adds UDP, can become G1P -> G6P -> glycolysis

508
Q

What are microfilaments?

A

Can shorten and lengthen very quickly -> lengthen = polymerization; shorten = depolymerization; gross movement of cell

509
Q

What are microtubules?

A

In centrosome (9 triplets) and cilia/flagella (9+2), dynein help cilia and flagella move (- end is anchored to MTOC)

510
Q

What is the secretory pathway?

A

ER -> Golgi -> Lysosome

511
Q

What are some functions of smooth/rough ER?

A

Smooth = synthesize lipids, metabolize carbs, detox of drugs; rough = protein synthesis, post-translational modifications

512
Q

What are viroids vs. prions?

A

Viroids = circular DNA, self-cleaves to create more viroids; prions = changes alpha helices to beta sheets

513
Q

What is the order of sperm development?

A

Spermatogonium -> primary spermatocyte -> 2 secondary spermatocyte -> 2 spermatids per spermatocyte -> spermatoza -> epididymis

514
Q

What are the stages of early development?

A

Zygote -> cleavage -> morula -> trophoblasts + embryoblasts -> blastocoel -> amniotic cavity -> epiblasts/hypoblasts -> bilaminar disk -> primitive sterak -> gastrulation -> trilaminar disk -> neurulation -> mesoderm forms notochord -> chaange in ectoderm -> neural plate becomes neural tube -> neural crest cells form

515
Q

What is saltatory conduction?

A

AP jumps from node to node

516
Q

What are GPCRs?

A

7 transmembrane domains, only in eukaryotes, G-proteins = proteins that can bind to GTP + GDP (ex. enzymes that produce 2nd messengers)

517
Q

What are ligand-gated ion channels?

A

Found in neurons, transmembrane ion channels that open/close in response to binding of a ligand

518
Q

What is the pathway of gas exchange in the respiratory system?

A

O2 -> layer of fluid -> epithelial fluid -> basement membrane -> connective tissue -> basement membrane -> endothelial cells -> capillary -> RBCs

519
Q

What do astrocytes do?

A

Form BBB, structural support, glial scar, monitoring interstitial fluid, clear synapses (the “C” in astrocytes stands for CNS)

520
Q

What do microglia do?

A

Inflammatory response (reactive oxygen species), phagocytosis, antigen presentation

521
Q

What is the blood flow in the heart?

A

Superior vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonory valve -> LUNGS -> left atrium -> mitral/bicuspid valve -> left ventricle -> aortic valve -> HEART

522
Q

What is the difference between arteries and veins?

A

Arteries = away from heart, high pressure, low volume; veins = towards heart, low pressure, high volume

523
Q

What is the epiglottis?

A

Flap of cartilage that closes off airway when you are sweating

524
Q

What are some functions of the pancreas?

A

Production of enzymes (amylase, protease, lipase, ribonuclease, HCO3-)

525
Q

What are some functions of the small intestine?

A

Absorption of food molecules and water, villi (active transport and facilitated diffusion), structure = duodenum, jejunum, ileum

526
Q

What are some functions of the large intestine?

A

Absorption of water, bacterial flora (produce vitamin K)

527
Q

What is the point of fatty acid oxidation?

A

IN MITOCHONDRIA: yield more acetyl-CoA (inhibited by insulin, enhanced by glucagon), rate limiting = carnitine acyltransferase; 4 steps = oxidation (FADH2 product), hydration, oxidation (NADH product), split off an acetyl-CoA

528
Q

What is the point of fatty acid synthesis?

A

IN CYTOSOL; Citrate -> acetyl CoA+OAA -> acetyl CoA becomes malonyl via acetyl CoA carboxylase -> malonyl CoA x 2 via enzyme FA synthase -> high insulin triggers fatty acid synthesis -> fatty acid + glycerol = triglycerides (stored in adipocyte cells)

529
Q

What is the point of the urea cycle?

A

Amino acid metabolism: ammonia (toxic, cannot be excreted properly); urea = non-toxic, easily excreted, process of converting ammonia -> urea (occurs in cytoplasm and mitochondria)

Melanie's MCAT flashcards (6 decks)

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