MCAT Bio/Biochem Flashcards
(148 cards)
1
Q
How does cholesterol affect membrane fluidity at both high and low temperatures?
A
High Temp: Cholesterol stabilizes phospholipids and decreases fluidity
2
Q
What are the key differences between Meiosis and Mitosis?
A
Both Meiosis and Mitosis consist of the separation of sister chromatids
3
Q
Which viruses require RNA replicase? How about RNA transcriptase?
A
RNA replicase is only needed for negative-sense single-stranded RNA viruses –> Creates positive-sense RNA strands to be translated using host cell machinery
4
Q
What are the 3-letter and 1-letter abbreviations for every amino acid?
A
Every 3-letter and single letter abbreviation of amino acids
5
Q
Where does the active replication or synthesis of viral proteins occur in host cells?
A
Viral proteins are synthesized using host ribosomes, which are located in the rough ER
6
Q
What are viral envelopes primarily made up of? Where are viral genetic material and associated enzymes located?
A
Viral envelopes are primarily made up of phospholipids (cell membrane) and glycoproteins (recognition and interaction with cell receptors); Viral genetic material and associated enzymes are contained in the virion, not the envelope
7
Q
Describe the investment phase of glycolysis
A
By the end of the investment phase of glycolysis (first 5 steps), 1 molecule of gluose is converted to –> 2 G3P + Net loss of 2 ATP
8
Q
What is difference between facultative and obligate aerobes/anaerobes?
A
Facultative Aerobes can use oxygen as an electron acceptor in presence of oxygen, but it can also survive in an anaerobic environment by deriving energy solely from glycolysis and subsequent fermentation
9
Q
Which enzymes are used ONLY in gluconeogenesis and not glycolysis?
A
Enzymes only used in Gluconeogenesis include: Pyruvate carboxylase, Fructose 1,6-bisphosphatase, Glucose 6-phosphatase
10
Q
What is the rate-limiting step of Glycolysis? Which enzyme is involved in this step?
A
Rate-limiting step of Glycolysis is the phosphorylation of F6-P into F1,6-BP by the enzyme Phosphofructosekinase-1; Uses 1 ATP
11
Q
How are Glucokinase and Hexokinase regulated, respectively?
A
Hexokinase is inhibited by high levels of G6-P, Glucokinase inhibited by low blood sugar
12
Q
What are the functions of DNA Polymerase A and DNA Polymerase D?
A
DNA Polymerase A initiates synthesis in eukaryotes; DNA Polymerase D synthesizes new nucleotides to each preceding 3’ OH group (Requiers RNA primer);
13
Q
What is the function of Histone Deacetylase?
A
Histone Deacetylase removes negatively charged acetyl groups, causing them to be more positively charged and interact more closely with DNA surrounding them –> Reduces transcription of genes on DNA
14
Q
What is 3’-5’ exonuclease activity? Which enzymes posses this activity?
A
DNA Polymerase can perform a proofreading mechanism termed 3’-5’ exonuclease activity, where DNA Polymerase excises mismatched bases and replaces them with the correct base at that position
15
Q
What is the overall rate of a reaction consisting of three individual reaction rates: K1, K2, and K3?
A
Overall Rate of Reaction = K1 x K2 x K3…etc
16
Q
What is alternative splicing? What is its benefit?
A
Alternative Splicing is a mechanism through which some exons can be spliced out, allowing for # of proteins to be 10x that of # of genes
17
Q
What are the definitions of Penetrance and Expressivity, respectively?
A
Penetrance = How often a mutation is phenotypically expressed (Mutated genotype should display disease phenotype), Expressivity = Intensity or extent of variation in a phenotype
18
Q
What is the relationship between genetic linkage and physical location of genes on a chromosome?
A
Genes that are further apart are less likely to be linked
19
Q
What are the equations for allele frequency in a population under Hardy-Weinberg equilibrium?
A
Allele Frequency Equations: 1) p + q = 1 2) p^2 + 2pq + q^2 = 1
20
Q
What is a key intermediate in the Kreb’s Cycle that is used in the export of gluconeogenic substrates from the mitochondria?
A
Malate is a key intermediate in the Kreb’s Cycle that is used in the export of gluconeogenic substrates from the mitochondria
21
Q
What is the function of Complex I in the ETC?
A
Complex I receives electrons from NADH and results in translocation of 4 protons across inner mitochondrial matrix
22
Q
What is the irreversible, rate-limiting step of the Kreb’s Cycle?
A
The decarboxylation of isocitrate to form A-ketoglutarate (5 C’s) is the irreversible, rate-limiting step of the Kreb’s Cycle
23
Q
What is epidemiology?
A
Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations
24
Q
Which nucleotides are Purines? Which are Pyrimidines?
A
Purines: A and G (Pure as Gold) Pyrimidines: C, U and T (CUT the Py)
25
What are the first two steps of Glycolysis? What enzymes catalyze these reactions?
Step 1: Glucose --> G6P (Catalyzed by Hexokinase) Step 2: G6P --> F6P (Catalyzed by G6P isomerase)
26
What is Substrate-Level Phosphorylation? When does it occur during Glycolysis?
*Substrate-Level Phosphorylation: Process by which a phosphate group is transferred to ADP/GDP to produce ATP/GTP *Occurs during anaerobic Glycolysis when ATP is produced from the breakdown of 1,3-BPG and PEP
27
Do eukaryotes and/or prokaryotes undergo ETC? If both, what is the difference between eukaryotic and prokaryotic ETC?
Both eukaryotes and prokaryotes perform the Electron Transport Chain; They differ in the location of the ETC (Eukaryotes = mitochondrial membrane, Prokaryotes = Cell Membrane)
28
What is the precursor molecule to Isocitrate?
The precursor molecule of Isocitrate is cis-aconitate
29
What is the role of Citrate Synthase? How do NADH and ADP act as regulatory molecules to Citrate Synthase in the Krebs cycle?
Activation of Citrate Synthase increases the production of citrate and subsequently, cis-aconitate (Catalyzed by Aconitase) ------------------------------------- NADH: Inhibitor of Citrate Synthase, ADP: Activator of Citrate Synthase
30
What is the function of Allolactose?
Allolactose binds to repressor, causing it to dissociate from the operator region
31
What are three types of noncoding RNA?
Three types of noncoding RNA include tRNA, siRNA, and miRNA
32
What is cDNA? How is it made?
cDNA does not include introns! cDNA = complentary to mRNA (introns have been spliced out following transcription; reverse transcriptase used to make cDNA)
33
What is the charge of DNA and why? Explain the apparatus for gel electrophoresis, specifically the charge of the apparatus.
DNA molecules are negatively charged, so they move towards the anode. Apparatus works like electrolytic cell (Negative cathode, Positive anode)
34
Explain what each type of Blotting is used for: Southern, Western, Northern
Southern = DNA, Western = proteins, Northern = RNA
35
What are ddNTPs?
Dideoxynucleotide Triphosphates (ddNTP) are nucleotides that lack an OH group at both the 2' and 3' carbons
36
What is Acetylation? What is the effect of increasing Acetylation on the overall rate of gene transcription?
Acetylation removes a positive charge on Lysine residues in histone proteins, decreasing the level of attraction between + charged histones and - charged DNA backbone --> Creates space between histone and DNA, making gene transcription easier
37
What are the structures of all 4(5) nucleotides?
Structures of nucleotides!
38
Describe the flow of ions across the cell membrane during the peak of an action potential.
Peak of action potential = Na not flowing, K flowing out
39
What is the specialized part of a neuron where action potentials are summated?
Action potentials are summated at a specialized part of a neuron called the Axon hillock
40
What are the functions of the following brain regions: Temporal lobe, basal ganglia, inferior colliculus?
*Temporal Lobe = Houses auditory cortex and processes auditory info *Basal Ganglia = Controls fine motor movement *Inferior colliculus = Part of auditory pathway that transmits signals to medical geniculate nucleus located within the thalamus
41
What are Efferent nerves responsible for?
Efferent nerves = Responsible for carrying out reflexive action (Ex: Extension of leg)
42
What are the resident macrophages of the CNS?
Microglia are a type of glial cell that function as the resident macrophages of the CNS
43
Which neurotransmitter is crucial to muscle contraction?
Acetylcholine (ACh) = Neurotransmitter released by somatic neurons in order to induce muscle contraction
44
What are Nociceptors? Are they Afferent or Efferent? Sensory or Motor?
Nociceptors are neurons that convey sensations of pain to the CNS --> These neurons are Sensory and Afferent
45
Which of the following induce changes in how stimuli are encoded via effects on gene expression: Steroid Hormones, Peptide Hormones, Methylation?
Steroid Hormones and Methylation can affect gene expression (Steroid Hormones = Bind with nuclear receptors that regulate expression through transcription factors, Methylation = DNA-level covalent modification that is an example of epigenetics) ------------------------------------------------ Peptide Hormones do not affect gene expression (Peptide Hormones = Bind to membrane receptors and trigger intracellular signaling cascades that impact cellular activity)
46
During periods of extended fasting, free fatty acids are converted to what? Where are these molecules used?
During periods of extended fasting, free fatty acids are converted to ketone bodies, which may be utilizes by neurons via the TCA cycle
47
Which fatty acid derivative prevents the loss of water from the leaves of plants? Why?
Biological waxes are fatty acid derivatives that prevent the loss of water from their leaves (long-chain fatty acids esterified to long-chain alcohols --> Hydrophobic and used as waterproofing)
48
What is Enzymatic Promiscuity?
Enzymatic Promiscuity refers to the case in which a single enzyme can exercise catalytic effects on a wide variety of structurally diverse substrates (not highly specific)
49
What role does each of the following play in the transport of Cholesterol: VLDL, HDL, Chylomicrons, LDL?
LDL= Maojr transporter of cholesterol to the tissues of the body; HDL = also transports cholsterol, but brings it to the liver; Chylomicrons and VLDL = Primarily transport triglycerides
50
Which enzymes catalyzes breakdown of fatty acids and throuh what mechanism? Where is this enzyme expressed?
Hormone-sensitive Lipase is highly expressed in adipose tissues and steroidogenic tissues (adrenal cortex, ovaries, testes) --> This lipase catalyzes the breakdown of triacylglycerols to fatty acids and glycerol through the hydrolysis of ester linkaes
51
How would removing the anterior pituitary gland affect tropic hormones and their function?
Anterior pituitary gland secretes vital Tropic Hormones, one of which is Thyroid-stimulating Hormones (TSH) --> TSH increases the basal metabolic rate
52
What type of Steroid hormone is Aldosterone? What are the effects of Aldosterone on sodium, potassium, and water?
Aldosterone is an adrenal mineralocorticoid --> Acts on distal tubules and collecting ducts of nephrons to stimulate Na retention, water retention, and K secretion
53
All of the followin act as second messengers EXCEPT: cAMP, ATP, cGMP, Calcium ions
Calcium ions, cAMP, and cGMP are common secondary messengers
54
How do Steroid and Peptide hormones induce physiological effects, respectively? Timing?
Steroid Hormones = Pass through plasma membrane and affect gene transcription (Longer-lasting) ---------------------------------- Peptide Hormones = Act through more rapid second messenger pathways
55
What are the 4 types of Pancreatic cells and what are their functions?
Alpha cells = Produce glucagon, Beta cells = Produce insulin (Type 1 diabetes), Delta cells = Produce somatostatin, Epsilon cells = Produce Ghrelin
56
Where are CRH and ACTH secreted, respectively? What is the function of ACTH?
*CRH = Secreted by the hypothalamus *ACTH = Released by anterior pituitary gland, Acts on adrenal cortex to release cortisol
57
What is the physiological effect of Insulin?
Insulin does all of the following: 1) Stimulates glycogenesis (Glycogen synthesis) 2) Increases triglyceride synthesis 3) Decreases fatty acid oxidation (store sugars rather than break down fats for energyg use) 4) Facilitates uptake of glucose into cells, resulting in reduced blood glucose levels
58
What is the function of Luteinizing Hormone? In males and females?
*Females = Luteinizing Hormone causes mature follicles on the ovaries to undergo ovulation (11-21 days of menstrual cycle) *Males = LT binds to receptor on Leydig cells and stimulates Testosterone synthesis and secretion
59
What is the correct ejaculatory pathway of sperm?
SEVEN UP = Seminiferous tubules, Epididymis, Vas deferns, Ejaculatory ducts, Nothing, Urethra, Penis
60
When does ovulation occur? How do oocytes change during this process?
After puberty, ovulation begins to occur --> Diploid primary oocytes mature into haploid secondary oocytes
61
What is the relationship of the Hypothalamic pituitary axis to ovarian function? Which molecules are released/stimulated by this axis?
Hypothalamic pituitary axis is closely involved in ovarian activity: Releases FSH and LH from anterior pituitary --> Stimulates folliculogenesis and promotes secretion of Progesterone and Estrogen
62
What is GnRH? What is its normal role in males?
Gonadotropin-releasing hormone (GnRH) is a tropic peptide hormone produced by the hypothalamus --> GnRH releases LH and FSH and eventually regulates the release of Testosterone levels and sperm count
63
What is the average length of the Menstrual cycle? How can this length differ and why?
Menstrual cycles average 28 days, but can be as long as 35 days --> Variability due to the follicular phase
64
What are the correct stages of embryonic development from earliest to latest?
Correct stages of embryonic development from earliest to latest: Blastula --> Morula --> Gastrula --> Neurulation
65
Which hormone promotes and maintains lactation?
Prolactin is the predominant hormone that promotes and maintains lactation
66
What is hCG? When is it released? What is its structural and physiological function?
Human chorionic gonadotropin is a peptide hormone released by the embryo shortly after implantation --> hCG mimics LH and maintains the corpus luteum (Maintains estrogen and progesterone levels)
67
What triggers ovulation in the menstrual cycle?
In the menstrual cycle, ovulation is triggered by a brief and intense spike of LH
68
What are the functions of Vitamins A, D, E, and K?
*Vitamin A (retinol/al) = Assists in vision *Vitamin D = Promotes calcium and phosphate absorption from the gut *Vitamin E = Best-known as antioxidant *Vitamin K = Promotes coagulation
69
What is the correct order of events in the developmental process of oocytes?
Developmental Process of Oocytes: Meoisis I initiation --> Puberty --> Meiosis I completion --> Meiosis II initiation --> Fertilization --> Meiosis II completion
70
Which of the following metabolites are LEAST likely to passively diffuse through the plasma membrane: Methane, H2O, H2, CO2? Why?
Water is the least likely to freely diffuse through the plasma membrane due to its permanent dipole moment
71
How does cholesterol affect biological membranes at high temperatures?
At high temperatures, Cholesterol increases membrane stability through attractive van der Waals interactions with neighboring phospholipid tails
72
Which cellular membrane structure is rich in cholesterol?
Lipid Rafts are regions of the plasma membrane that are very rich in Cholesterol
73
What is the most common method of transport for cholesterol across the plasma membrane?
Calcium is most commonly transported across the plasma membrane through secondary active transport via an Antiporter (1 Ca2+ out, 3 Na+ in)
74
How does cholesterol affect membrane fluidity at low temperatures?
At low temperatures, cholesterol acts to prevent stacking/clustering of fatty chains --> Maintains/increases fluidity
75
How do eukaryotes and prokaryotes differ in their plasma membrane composition? Hint: Cholesterol, Peptidoglycan
*Only eukaryotes have cholesterol within its cell membrane ------------------------------------------- *Peptidoglycan is a unique membrane feature of gram positive bacteria
76
Where is surfactant found? What is its function?
Surfactant is found in the alveoli and serves to reduce surface tension
77
Which blood type is a universal recipient?
Blood type AB is a universal recipient
78
What is piloerection? When does it occur?
Piloerection = Erection of the hair of the skin due to contraction of the tiny muscles that elevate the hair follices above the rest of the skin to trap heat
79
How does Cardiac arrest result in acidosis?
Cardiac arrest (Cessation of muscular activity, including that of diaphgram) --> Reduced gas exchange, increased serum [CO2] (respiratory acidosis), and increased lactic acid production due to anaerobic metabolism --> Decrease blood pH (Causing ACIDOSIS)
80
Where is low pH blood predicted to be found? Why is this the case?
Lower pH blood is predicted to be found in the systemic veins and pulmonary arteries (carry deoxygenated blood from right side of heart to lungs to be oygenated) -- Reason: After gas exchange in tissues, blood typically has a higher CO2 content, lower O2 content, and lower pH
81
Why can people with AFib live for years, but not VFib?
Ventricles pump blood into pulmonary and systemic circulation at high pressure, while the atria do the much less taxing job of moving blood into the ventricles
82
What provides electrical conduction to the left ventricle? Other ventricles?
Purkinje fibers provide electrical conduction to the ventricles
83
Which of the following molecules are involved in the clotting pathway: Thrombin, Angiotensin II, Thromboxane? What are the functions of each?
*Thromboxane = Hormone released from blood platelets (induces platelet aggregation and arterial constriction) *Thrombin = Enzyme in blood plasma that causes clotting of blood by converting fibrinogen to fibrin *Angiotensin = Peptide hormone that causes vasoconstriction to increase blood pressure (not involved in clotting pathway)
84
Where is bile released from? Where does it get released? Function of bile?
The gallbladder releases stored bile into the small intestine to emulsify fats
85
Where are polysaccharides broken down? What about disaccharides?
Polysaccharides broken down in mouth by salivary amylase. Disaccharides are broken down in the small intestine by enzymes known as disaccharidases
86
What is the function of Vasopressin? Where does it act?
Vasopressin (ADH) activity results in retention of water via reabsorption in the collecting duct of a nephron
87
What is the major function of the PCT and DCT, respectively? What is the primary driver/regulator for each?
*PCT = Site of major reabsorption and secretion (driven by sodium transport) *DCT = Site of hormone-controlled reabsorption and secretion
88
Which immune cells act most immediately against a bacterial pathogen following infection of a naive host? Why do these cells act fastest?
Neutrophils (part of the innate immune system) act most immediately against a bacterial pathogen following infection of a naive host --> They can respond more rapidly than B or T cells, which must be generated via clonal expansion from activated precursors
89
Where do lymphocytes originate? What are 2 types of lymphocytes?
All lymphocytes (B and T cells) originate in the bone marrow from hematopoetic progenitor cells
90
What is the site of antigen binding to an Ig molecule? Where is this region located? What forces hold the antigen and Ig molecule together?
The site of antigen binding to an Ig molecule is the variable region (located on the light and heavy chains); Held together by noncovalent interactions
91
What are professional antigen-presenting cells? Give 3 examples. What are the role of APCs?
*Professional antigen-presenting cells (APCs) are those which express MHC class II (Include B cells, dendritic cells, and macrophages) *APCs = Responsible for processing antigens and presented antigenic peptide fragments to cells of the adaptive immune system
92
What is the role of the spleen?
1) Storage of leukocytes (particularly monocytes), which become macrophages or dendritic cells upon reaching their target tissue 2) Aged erythrocytes are removed from circulation
93
What is adaptive immunity? What are 3 components of the adaptive immune response?
Adaptive Immunity = Branch of immunity that recognizes and responds to specific pathogens; Includes B lymphocytes (produces antibodies) and T lymphocytes
94
What systems are the following anatomical structures associated with: Lacteals, epiglottis, Larynx, Bronchi? Give definitions of each.
*Lacteals = Structures in the intestines associated with absorbing fat into the lymphatic system *Epiglottis = Flap of cartilage that covers the trachea the ensure that food properly reamins in digestive tract (part of respiratory system) *Larynx (voice box) = Part of respiratory system; located immediately above the trachea *Bronchi = Part of respiratory system
95
What autosomal monosomies are viable? What about autosomal trisomies?
*No viable autosomal monosomies *Only viable autosomal trisomies = Trisomy 21, 18, and 13
96
What is Aneuploidy? What is its cause?
Aneuploidy = Having too many or too few copies of a given chromosome; Results from nondisjunction in anaphase during cell division
97
Describe the structure of a chromosome and its two arms. What are the function of these arms?
A chromosome contains a centromere that separates the chromosome into 2 arms (p and q arms); Arms are used as part of the info needed to specify the location of a gene on a chromosome
98
What is the Michaelis constant?
Michaelis constant = Substrate concentration required to reach 1/2 of the maximal velocity (Km = 1/2*Vmax)
99
What is the effect of the Acetylation of Lysine?
Acetylation of Lysine --> Makes the residue neutral, lessening electrostatic attraction to DNA and promoting a less dense, loose chromatin structure (euchromatin) that is transcriptionally active
100
What are the names of the following bacteria by shape: Spherical, rod-shaped, spiral-shaped?
*Spherical = Cocci *Rod-shaped = Bacilli *Spiral-Shaped = Spirilli
101
What are conformers? What are constitutional isomers?
*Conformers = Can freely convert between forms with no bond breaking *Constitutional or structural Isomers = Have fundamentally different connectivity between atoms
102
How do you know if a side chain of an amino acid is charged at a specific pH?
If pH < pKa --> Side chain is protonated (Has an H)
103
What is the role of arachidonic acid in the biosynthesis of signaling molecules?
Arachidonic Acid = Precursor for biosynthesis of 20C eicosanoid signaling molecules (Prostaglandins, thromboxanes, leukotrienes)
104
Do prokaryotes and eukaryotes have both exons and introns?
Most bacterial genes do not contain introns
105
What are transmembrane proteins? What is their function?
Transmembrane proteins = Many are glycoproteins; Pass all the way through the cell membrane and facilitate membrane transport
106
What are the SA and AV nodes? What are their function?
Rhythm of heart contractions is controlled by the sinoatrial (SA) node, found on the roof of the right atrium; Cells in SA node periodically send out action potentials --> Gap junctions allow action potential to propagate into the atria and cause contraction --> Blood pushed into ventricles; Atrioventricular (AV) node propagates action potential through ventricles
107
What happens to insulin secretion and G6PD activity after carbohydrate-rich meal?
Insulin secretion increases, G6PD activity increases
108
Hyperglycemia (where insulin cannot effectively induce the uptake of glucose by cells) would lead to the presence of which molecules in the urine?
Glucose, Ketone bodies
109
Meiosis I results in 2 of what kind of cells with how many chromosomes and sister chromatids?
2 haploid cells with 23 chromosomes (each chromosome has 2 sister chromatids)
110
In a Lineweaver-Burk plot, what are the x and y-axes? What are the x and y-intercepts?
*X-axis = 1/[S], Y-Axis = 1/V *X-intercept = -1/Km, Y-intercept = 1/Vmax
111
What does Lipophilic mean? Relevance to blood-brain barrier?
Lipophilic = Lipid-soluble; Readily passes through the blood-brain barrier
112
What is Neurulation?
*Neurulation = Induction of ectoderm (outer layer of gastrula) to differentiate into the nervous system (Nervous system is derived from the ectoderm)
113
What are a few characteristics of electron carriers? Are all hydrophobic? Which are not, if any?
Most are mobile and hydrophobic; Cytochrome c is highly water-soluble (hydrophilic)
114
Which location is expected to have the highest number of glucagon receptors? What is the function of glucagon?
*Liver = Highest number of glucagon receptors *Glucagon = Released by pancreas in response to low blood glucose levels; Purpose is to increase glycogenolysis to increase blood glucose; glycogen stored in liver is broken down to create glucose that is released into the bloodstream
115
What is an organic compound? What is an organic acid?
*Organic compound = Must contain C and H connected by covalent bond *Organic acids = Weak acids with the acidic H bonded to an O (Generally have formula R-CO2H)
116
What are the effects of aldosterone?
Aldosterone = Increases H2O and Na reabsorption from kidney, while exchanging K ions for Na ions --> Result: K secretion increases, Na reabsorption increases
117
Are the following modifications post-transcriptional or post-translational: Glycoslyation, Splicing, Polyadenylation?
*Post-transcriptional = Polyadenylation and Splicing *Post-translational = Glycosylation
118
Which bacterial process are viruses directly involved in? Describe the process.
Transduction = Form of horizontal gene transfer in bacteria, in which bacteriophages (viruses that infect bacteria) transmit genomic material
119
Which membrane-bound enzyme is responsible for converting LCFAs to their CoA derivatives in Beta oxidation? Where is this enzyme located?
Thiokinase, Outer mitochondrial membrane
120
Describe SDS-PAGE.
SDS-PAGE = Allows proteins to be separated on mass alone; SDS is strong anionic detergent; Proteins migrate toward positively-charged pole; Smaller distance traveled = Larger protein
121
What kind of solvents favor SN2 reactions?
Polar aprotic solvents (Ex: Acetone, DMSO)
122
Definition of passive vs. natural immunity?
*Passive Immunity = Transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another *Natural immunity = Immunity present at birth, prior to exposure to a pathogen or antigen
123
What is the function of the G2-M checkpoint?
G2-M Checkpoint = Ensures that DNA has been replicated accurately
124
What is the function of the G1-S checkpoint?
G1-S Checkpoint = Cell must have enough organelles and be large enough to proceed to DNA replication
125
Match the term with the correct definition: *Apoptosis + Necrosis *Uncontrolled Cell death, Naturally-triggered event
*Apoptosis = Naturally-triggered event *Necrosis = Uncontrolled cell death
126
How do stem cells change as they progress from totipotency to pluripotency to multipotency?
1) Lineage potential decreases (Lose ability to give rise to a broad range of tissue types) 2) DNA increasingly methylated (Inhibits transcription) --> Decreases prevalence of euchromatin, or "open chromatin"
127
What is Paracrine signaling activity?
Paracrine activity = Involves secretion of local signaling molecules
128
How will consistently high levels of progesterone near the beginning of the menstrual cycle influence ovulation?
Prevent woman from ovulating --> Estrogen and progesterone negatively feedback on GnRH; High levels of progesterone leads to reduced release of LH and FSH
129
What does the blastopore give rise to in the protostome and deuterostome, respectively?
*Protostome = Blastopore becomes mouth *Deuterostome = Blastopore becomes anus
130
Describe the following sub-mesodermal tissue layers: Chorda, intermediate, lateral plate, paraxial.
*Chorda-mesoderm = Develops into the notochord *Intermediate mesoderm = Develops into gonads and kidneys *Lateral plate mesoderm = Develops into gut wall and circulatory system *Paraxial mesoderm = Develops into skeletal muscle and cartilage
131
Where is the notochord and what is its function?
Notochord = Located ventral to the neural tube; Provides primitive axis of the developing embryo and in vertebrates, develops into the vertebral column
132
Why do restriction enzymes interact/bind with the major groove of the intact DNA double helix?
1) Offers more space for access to bases 2) Allows them to establish a more unambiguous pattern of H-bonding for proper sequence recognition
133
What are Size-exclusion chromatography and Affinity chromatography, respectively?
*Size-exclusion chromatography = Used to purify proteins based on size *Affinity chromatography = Highly specific form of purification in which the stationary phase is known to bind to the protein of interest (Ex: Immunoaffinity chrom. w/ antibodies or IGs)
134
What is Thin-layer chromatography? What is the Rf value?
*Thin-layer chromatography = Includes polar stationary phase and nonpolar mobile phase (More polar compounds interact w/ plate and travel shorter distance); Rf = Measure of distance traveled by the sample in comparison to the solvent front
135
What is Reversed-phase chromatography?
*Reversed-phase chromatography = Stationary phase of column is hydrophobic and mobile phase is hydrophilic (Polar molecules elute more quickly)
136
What is Ion-exchange chromatography?
*Ion-exchange chromatography = Separates compounds on basis of charge
137
What is the 2nd law of thermodynamics?
Second Law of Thermodynamics = Spontaneous rxns yield net entropy increase; A catabolic process may be coupled with an anabolic reaction, yielding a net increase in entropy
138
What is the energetic yield of the following species: ATP, FADH2, NADH?
ATP = 1, FADH2 = 1.5, NADH = 2.5
139
What is the function of insulin?
Insulin = Released in response to high blood glucose levels; Stimulates glycolysis and glycogenesis; Decreases rate of gluconeogenesis
140
Which type of eukaryotic RNA is coding vs. non-coding?
*Non-Coding = MicroRNA, snoRNA (small nuclear RNA), and tRNA *Coding = mRNA and hnRNA
141
Which nucleic acids can catalyze biological reactions?
Only RNA (Ribozymes = important roles in protein production and packaging)
142
What are GAPs and GEFs? What are their function?
*GAPs = GTPase-activating proteins; Induce G proteins to hydrolyze bound GTP, activating G protein *GEFs = Guanine nucleotide exchange factor; Promotes GDP release, activating G protein
143
How are thyroxine and steroid hormones similar? Different?
Similar = Similar mechanism of action; They both act by binding cytosolic receptors and entering the nucleus to alter gene trasncription Different = Tissue of origin and chemical structure
144
How many Hydrogen bonds are found in A, T, C and G, respectively?
Adenine and Thymine = 2 H bonds Cytosine and Guanine = 3 H bonds
145
Why does Eukaryotic DNA polymerase require a free 3' OH goup? What provides this free group and what is it synthesized by?
OH group is necessary b/c it binds to DNA polymerase, which otherwise cannot initiate synthesis
146
Which type of RNA is most active during post-transcriptional processing? What is the function of this RNA type?
snRNA = Combine with proteins to form the spliceosome, which splices introns out of the pre-mRNA transcript
147
How do eukaryotes and prokaryotes differ in their release factors?
*Prokaryotes = Translation requires multiple release factors (RF's) *Eukaryotes = Requires only 1 release factor, eukaryotic translation termination factor 1 (eRF1)
148
How are stop codons recognized to ensure proper termination of translation?
Stop codons are only recognized by protein release factors (no tRNA molecules bind to these codons)
