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Biochemistry PA-CAT Review > Biochemistry Review > Flashcards

Biochemistry Review Flashcards

1
Q

Blood is maintained at a pH of about 7.4 through several mechanisms, such as the carbonic acid/bicarbonate buffering system and respiration removing carbon dioxide from the body. A laboratory measures the blood pH and bicarbonate ion concentration of trained endurance athletes performing high-intensity exercise under hypoxic conditions and normal conditions. The bicarbonate ion concentration drops under hypoxic conditions compared to normal conditions. What happens to the athletes’ blood pH under hypoxic conditions?

A

Lower

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2
Q

A hospital lab indicates a urine sample pH of 5.0 in a patient presenting with symptoms of kidney stones. What is the actual hydrogen ion concentration of the urine sample?

A

10^-5 M

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3
Q

The concentration of hydrogen ions [H+] in a solution is 1 x 10^-7 moles/L. What is the pH of the solution?

A

7

(pH of a solution can be calculated as: pH = -log[H+] = -log[H+]

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4
Q

Which of the following levels of protein organization involves the interaction between multiple protein chains?

A

Quaternary

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5
Q

When a protein is denatured, which of the following happens to its function?

A

It ceases to function

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6
Q

What are proteins made of?

A

Amino acids

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7
Q

What pair of functional groups is found in each of the 20 amino acids?

A

Amino group and carboxyl group

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8
Q

What amino acid is composed of a bulky structure that includes aromatic residues?

A

Tryptophan

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9
Q

What kind of bond is present between two amino acids?

A

Peptide bond

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10
Q

A peptide bond forms through which process?

A

Dehydration synthesis

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11
Q

When a peptide bond forms between two peptides to make a polypeptide, what does the carboxylic acid group of the amino acid bind to on another amino acid make this peptide bond?

A

Amino group

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12
Q

Hemoglobinopathies may affect the structure or production of hemoglobin molecules.

Which of these diseases is divided by type, based on alpha and beta subunits, with disease severity ranging from mild to incompatible with life?

A

Thalassemia

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13
Q

Allosteric moderators influence the oxygen affinity of hemoglobin.

Which moderator is known for T-state stabilization under hypoxic conditions?

A

Bisphosphoglycerate

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14
Q

What phenomenon is observed with the binding and dissociation of oxygen in hemoglobin?

A

Positive cooperativity

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15
Q

A protein in erythrocytes binds to oxygen and transports it from the lungs to tissues. How many oxygen molecules can be transported by a single molecule of hemoglobin?

A

4

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16
Q

Which part of hemoglobin binds to oxygen?

A

Heme group

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17
Q

Statins treat high cholesterol levels, placing them among the most commonly prescribed medications in the United States. Some statins, like atorvastatin and simvastatin, are primarily metabolized by CYP450 enzyme CYP3A4. Other statins, like pravastatin, are not significantly metabolized by CYP3A4. Cyclosporine, an immunosuppressant, is a strong inhibitor of CYP3A4. A patient receiving cyclosporine presents with high cholesterol. What statin regimen is best for this patient?

A

Pravastatin

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18
Q

What substance is output by the liver following its metabolism of toxic ammonium ions?

A

Urea

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19
Q

Where in the body is the cytochrome p450 protein found in the highest concentration?

A

Liver

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20
Q

What bleeding disorder is characterized by a deficiency of factor VIII?

A

Hemophilia A

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21
Q

What is the main function of fibrinogen in the blood coagulation cascade?

A

Initial blood clot formation

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22
Q

What is the primary function of osteoclasts in relation to the structure and function of bone?

A

Reabsorption of bone

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23
Q

What do osteoblasts manufacture during the bone formation process?

A

Osteocalcin

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24
Q

A patient presents with a disease caused by the destruction of beta-cells of the pancreas and hyperglycemia.

What serum glucose level is likely to be observed?

A

150 mg/DL

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25
Q

What outcome related to alpha-cells is likely to result due to type I diabetes?

A

Increased glucagon secretion

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26
Q

A patient with diabetes demonstrates improper production of insulin. What consequence may occur?

A

Decreased glucose entry into muscle

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27
Q

A patient consumed a well-balanced meal several hours ago. What occurs inside liver tissue as a result of the time lapsed after eating?

A

Gluconeogenesis

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28
Q

A patient rests for 20 minutes after consuming a well-balanced meal. What occurs inside muscle tissue during this process?

A

Glucose entry

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29
Q

Multiple pathways enable energy currency to be derived from ingested food; this currency fuels vital cellular functions. What catabolic process results in the greatest amount of this currency?

A

Cellular respiration

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30
Q

Congestive heart failure is a large public health burden that may be treated with several types of hormones. Valsartan/sacubitril is a promising treatment for congestive heart failure. This medication degrades neprilysin, a peptidase that targets vasoactive peptides such as angiotensin. How does angiotensin cause a cellular response?

A

Initiating a signal transduction cascade and activating second messengers

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31
Q

Why are the target receptors of steroids often found within the nucleus of a cell?

A

Steroids alter gene expression

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32
Q

What system is responsible for the majority of hormone secretion and regulation in the body?

A

Endocrine

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33
Q

Improper activity of an epidermal growth factor receptor at the cell membrane may result in cancer. Which type of receptor may be involved?

A

Enzyme-linked receptor

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34
Q

A hormone binds to an adrenoreceptor during the “flight or fight” response. Which type of receptor facilitates this process?

A

G-protein-coupled receptor

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35
Q

A ligand binds to an external domain. A stepwise process ensues, resulting in a change in the electrical properties of the cell. Which type of receptor facilitates this process?

A

Ionotropic receptor

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36
Q

A ligand binds to a transmembrane protein and causes autophosphorylation of tyrosine in the cytoplasmic domain. This creates a binding site for effector proteins. What ligand may participate in this process?

A

Growth factors

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37
Q

A signaling molecule binds to a cell membrane receptor. In a stepwise process, the alpha subunit of the receptor dissociates from the beta and gamma subunits. Which portion of this receptor activates a target protein, as exemplified by the stimulation of adenylyl cyclase?

A

Alpha

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38
Q

The cytoplasmic face of a sodium-potassium pump has sodium bound and becomes phosphorylated. What is directly induced by this event?

A

Conformational change

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39
Q

Vesicles containing neurotransmitters are tethered to the plasma membrane. Their release is triggered by calcium. What type of transport is being performed?

A

Bulk transport

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40
Q

Carrier proteins facilitate solute transfer across the cell membrane. Which of these structures carries two different molecules in opposite directions?

A

Sodium potassium ATPase

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41
Q

The sodium-potassium pump of the cell membrane uses ATP to establish a transmembrane electrical potential, where the extracellular environment is more positive than the intracellular environment. What form of transport is performed when anything positively charged attempts to flow down this established gradient?

A

Secondary active transport

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42
Q

Which moiety of the plasma membrane typically demonstrates both intracellular and extracellular orientation?

A

Phospholipid head

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43
Q

Adenosine triphosphatases (ATPases) are ion pumps that span the lipid bilayer. Like all proteins, ATPases are composed of many amino acids. Where would you expect to find the most isoleucine residues in an ATPase?

A

Interacting with the hydrophobic lipids

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44
Q

What is the phospholipid bilayer structure comprised of, making it “dual in nature”?

A

Hydrophilic head and hydrophobic tail

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45
Q

What is the main function of the phospholipid bilayer in the cell membrane?

A

Protection

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46
Q

What is the main function of proteins in the cell membrane that create membrane channels?

A

Cellular transport

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47
Q

Insulin-degrading enzyme (IDE) is a promising target for therapeutics to treat type 2 diabetes and Alzheimer’s disease. A kinetic study found that 1 mM ATP inhibits this reaction, but 1 mM magnesium relieves this inhibition. The Michaelis constant (KM) of the reaction in the absence of ATP and magnesium is approximately 2M. What might the KM be in the presence of ATP and in the presence of ATP and magnesium?

A

ATP: 3M, ATP and magnesium: 2M

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48
Q

The catalytic rate (rate limiting step) determines the rate of an enzyme-catalyzed reaction in which of the following situations?

A

Creating product with free enzyme

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49
Q

Considering the Michaelis-Menten equation, what is the value for the Michaelis constant (Km)?

A

1/2 V max

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50
Q

What category of enzyme is responsible for moving a functional group from one molecule to another?

A

Transferase

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51
Q

Sugars are easiest for the body to break down into quick energy. Which enzyme, found in saliva, can be used to obtain sugars from carbohydrates as soon as food enters the body?

A

Amylase

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52
Q

What process is taking place when aspirin is used to reduce the activity of the enzyme responsible for inflammation?

A

Enzyme inhibition

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53
Q

Once a substrate binds to the active site of the enzyme, what happens to the rate of the reaction?

A

Speeds up

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54
Q

Resveratrol, a compound found in red wine and grapes, may have anticancer properties. A laboratory study of resveratrol in hepatocellular carcinoma cell lines found that resveratrol activates an enzyme called sirtuin 1. Sirtuin 1 is a negative regulator of a kinase cascade that includes phosphatidylinositol 3’-kinase (PI3K) and AKT, a kinase downstream of PI3K. What effects does resveratrol treatment have on post-translational modifications of PI3K and AKT?

A

Decreased phosphorylation

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55
Q

What is the most common functional group added during post-translational modification?

A

Phosphate

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56
Q

Which post-translational modification is one of the most important and also non-reversible?

A

Proteolysis

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57
Q

A molecule is composed of a five-carbon sugar, a phosphate group, and four different nitrogenous bases. How can the structure of a molecule composed through polymerization of these units be described for eukaryotes?

A

Condensed

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58
Q

How many hydrogen bonds are formed between guanine and another of the four bases in a polynucleotide molecule?

A

3

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59
Q

Two strands of DNA are arranged in an antiparallel fashion. What is positioned across from the 5’ end of one strand?

A

3’ end of the opposite strand

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60
Q

Which of DNA bases can pair with adenine?

A

Thymine

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61
Q

What is composed of two polynucleotide molecules intertwining?

A

DNA

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62
Q

What replaces thymine when DNA is translated into RNA?

A

Uracil

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63
Q

Which type of mutation causes sickle cell disease?

A

Missense

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64
Q

How many sequence permutations are formed due to the degeneracy of the central dogma process?

A

64

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65
Q

What sequence of units marks the most common beginning of a protein sequence?

A

AUG

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66
Q

How many units compose the groups that specify amino acids during the central dogma process?

A

3

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67
Q

How many different base pairs have the potential to form a codon during the central dogma process?

A

4

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68
Q

A molecule enables RNA polymerase to bind to eukaryotic DNA. Where does this binding occur?

A

TATA box

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69
Q

What process protects the 5’ end of a newly formed mRNA molecule from degradation?

A

Addition of 7-methylguanosine

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70
Q

Which transcription factor has a TATA-binding protein?

A

TFIID

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71
Q

What enzyme facilitates the three-step process that generates tRNA?

A

RNA polymerase III

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72
Q

What enzyme facilitates the three-step process that generates mRNA?

A

RNA polymerase II

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73
Q

What describes the complementary base pairing arrangement of a double-stranded helical polymer?

A

2 hydrogen bonds between 1 purine and 1 pyrimidine

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74
Q

During what phase is a double-stranded helical polymer compacted with scaffolding proteins?

A

Interphase

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75
Q

What basic unit, composed by a double-stranded helical polymer and its associated proteins, forms chromatin?

A

Nucleosome

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76
Q

What associates with a double-stranded helical polymer to facilitate compaction?

A

Histome

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77
Q

What binds to a double-stranded helical polymer and is crucial for its formation of higher-order structures, such as the solenoid and zigzag model?

A

H1

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78
Q

What genome is organized in the nucleus?

A

Eukaryotic genome

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79
Q

What must regulatory elements bind to for transcription to occur in eukaryotic cells?

A

TATA box

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80
Q

What codon is responsible for starting the process of translation?

A

AUG

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81
Q

What does the transcription process produce?

A

Antiparallel complementary RNA strand

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82
Q

HER2 is a well-known proto-oncogene. The HER2 gene encodes a tyrosine kinase receptor called human epidermal growth factor receptor 2 (HER2). HER2 has roles in cell growth and cell division, and HER2 overexpression has been reported in many types of human cancers. HER2 dimerization leads to autophosphorylation, which leads to the activation of HER2. Given this information, how might a laboratory target HER2 to develop a novel treatment for cancer?

A

HER2 inhibitor

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83
Q

The RAS genes are the most frequently mutated oncogenes observed in human cancer. RAS is part of the mitogen-activated protein kinase (MAPK) signaling pathway, and the downstream effects of MAPK signaling are cell cycle progression. RAS exists in a non-active form bound to GDP and an active form bound to GTP. The transition between RAS-GDP and RAS-GTP is regulated by guanine exchange factors and GTPase-activating proteins. A mutant RAS protein is identified as insensitive to cytosolic GAP. What effects will this mutant RAS protein have if left unchecked?

A

Activate MAPK signaling and cause cell proliferation

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84
Q

What process involves the entire protooncogene jumping from one position to another in the genome under the control of promoter?

A

Translocation

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85
Q

How do tumor suppressor genes contribute to a reduction in cancer?

A

Stop cell cycle progression

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86
Q

Tumor suppressor genes utilize which of the following mechanisms to slow or prevent the development of cancer?

A

Apoptosis

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87
Q

What type of event activates a protooncogene?

A

Chromosomal rearrangement

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88
Q

A cancer-associated variant has been discovered in a sequence of regulatory DNA. Which type of sequence is most likely to be mutated if it recruits RNA polymerase?

A

Transcription factor

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89
Q

A cancer-associated variant has been discovered in a sequence of regulatory DNA. Which type of sequence is most likely to be mutated if activation and repression functions of a multi-subunit assembly operate during both initiation and elongation?

A

Mediator coactivator

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90
Q

A cancer-associated variant has been discovered in a sequence of regulatory DNA. Which type of sequence is most likely to be mutated if abnormal silencing of tumor suppressors has occurred?

A

Long non-coding RNA

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91
Q

Mutation of a regulatory sequence has occurred. Which type of sequence is most likely to be mutated if DNA methylation targeting has become aberrant?

A

Non-coding RNA

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92
Q

Mutation of a regulatory sequence has occurred. Which type of sequence is most likely to be mutated if a failure to mobilize and modify nucleosomes occurs?

A

Chromatin regulator

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93
Q

What target might a researcher explore if they want to prevent release of RNA polymerase from a transcript?

A

Rho

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94
Q

Which subunit of this RNA polymerase has demonstrated mutations that account for rifamycin-resistant tuberculosis strains?

A

Beta

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95
Q

Which structure of RNA polymerase is prevent from forming when fidaxomicin is administered for a Clostridium difficile infection?

A

Open complex

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96
Q

Which part of RNA polymerase contains N-terminal and C-terminal domains that recognize the UP-element on the DNA molecule?

A

Alpha two

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97
Q

Which part of RNA polymerase pairs with the beta subunit to form the active site?

A

Beta prime

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98
Q

Based on the structural classification of hormones, which of the following hormones is derived from cholesterol?

A

Glucocorticosteroids

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99
Q

What hormone class is derived from lipids?

A

Steroid

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100
Q

What hormone is responsible for stimulated gamete production?

A

Follicle-stimulating hormone (FSH)

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101
Q

What characteristic is associated with hydrophilic hormones?

A

Targets cell surface receptors

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102
Q

What type of hormone is glucagon when classified according to the endocrine gland where it is synthesized?

A

Pancreatic hormone

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103
Q

Which hormone has a complex structure and a half-life of 60-90 minutes?

A

Steroid

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104
Q

Why do steroid hormones have an extended half-life?

A

Hydrophobicity

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105
Q

Where are steroid hormones like aldosterone and cortisol found in the body?

A

Adrenal cortex

106
Q

What forms the backbone of all steroids, in addition to a single five-membered ring?

A

Three fused six-membered rings

107
Q

What must occur before this thiamine can function?

A

Phosphorylation

108
Q

If a patient has a deficiency of vitamin C, what may they present with?

A

Swollen and bleeding gums

109
Q

What can result from deficiency of folate?

A

Neural tube defect

110
Q

What is pantothenic acid a component of?

A

Coenzyme A

111
Q

What form does niacin take during redox reactions?

A

NADP+

112
Q

A patient of advanced age with a history of alcoholism presents with an inflamed tongue and demonstrates deficiency of a water-soluble micronutrient that is a cofactor of redox reactions. What is this compound a precursor for?

A

FAD

113
Q

What vitamin is crucial for blood clotting?

A

Vitamin K

114
Q

Which vitamin inhibits oxidation?

A

Vitamin E

115
Q

Which vitamin is synthesized in the skin following exposure to sunlight?

A

Vitamin D

116
Q

Which vitamin helps to maintain mucous membrane moisture?

A

Vitamin A

117
Q

Which micronutrient has an activation function by enabling an enzyme (deiodinase) to convert T4 to T3?

A

Selenium

118
Q

Which micronutrient is essential for the synthesis of thyroid hormone?

A

Iodine

119
Q

Which micronutrient is highly involved in oxygen transport?

A

Iron

120
Q

Which micronutrient is essential for neurotransmitter synthesis?

A

Copper

121
Q

Adenosine triphosphate must complex with which micronutrient to be biologically active?

A

Magnesium

122
Q

Which enzyme determines the rate-limiting step of cholesterol synthesis?

A

HMG-CoA reductase

123
Q

What process of creating energy breaks down triglycerides into fatty acids and glycerol?

A

Lipolysis

124
Q

What process marks the beginning of cholesterol biosynthesis?

A

HMG-CoA (3-hydroxy-3-methylglutaryl-coa) formation

125
Q

Which type of eicosanoid is responsible for stimulating the contraction of smooth muscles during childbirth?

A

Prostaglandins

126
Q

What is the main function of prostaglandins?

A

Induce fever and inflammation

127
Q

Arachidonic acid metabolism involves the hydrolysis of the sn-2 position on the phospholipid backbone by what phospholipase?

A

A2

128
Q

What unstable intermediary in the lipoxygenase pathway is converted to various leukotrienes?

A

Leukotriene A4

129
Q

What type of eicosanoid biosynthesis is suppressed through the inhibition of cyclooxygenase by nonsteroidal anti-inflammatory drugs (NSAIDs)?

A

Prostanoids

130
Q

What family of enzymes initiates the production of eicosanoids by releasing arachidonic acid?

A

Phospholipase a2

131
Q

What transfers triacylglycerols to adipose tissue?

A

Chylomicron

132
Q

What can be observed when abnormalities of lipoproteins occur due to diabetes?

A

Increased LDL

133
Q

What is rich in triglyceride and cholesterol, synthesized in the liver, and used by other organs?

A

Very low-density lipoprotein

134
Q

What performs reverse cholesterol transport?

A

High-density lipoprotein

135
Q

What condition results when the heart fails to receive the proper amount of oxygen-rich blood due to this buildup?

A

Coronary artery disease

136
Q

What condition is characterized by a temporary impediment of blood to the brain?

A

Transient ischemic attack

137
Q

What condition is secondary to atherosclerosis and causes lasting neurological damage?

A

Ischemic stroke

138
Q

What condition involves neurological symptoms from blockage of blood vessels by cholesterol?

A

Cerebrovascular disease

139
Q

Where does the breakdown from glycogen to glucose occur?

A

Liver and muscles

140
Q

What is the ATP usage and production in glycolysis?

A

2 used, 4 produced

141
Q

Which key regulatory enzyme of glycogen synthesis catalyzes the α-1,4 linkage in glycogen?

A

Glycogen synthase

142
Q

What molecule is the immediate donor of glucose for glycogen formation during glycogenesis?

A

Uridine diphosphate-glucose (UDP-Glucose)

143
Q

In the final step of gluconeogenesis, which substrate undergoes hydrolyzation?

A

Glucose 6-phosphate

144
Q

How does excessive alcohol consumption affect the gluconeogenesis pathway and subsequently lead to ethanol-induced hypoglycemia?

A

Accumulation of lactate

145
Q

When would the body choose to switch from glycolysis to gluconeogenesis?

A

During starvation

146
Q

What enzyme is used in both gluconeogenesis and glycolysis?

A

3-phosphoglycerate kinase

147
Q

Fructose 1,6-bisphosphatase (FBP) catalyzes the removal of a phosphate group from fructose 1,6-bisphosphate to form fructose-6-phosphate, a key step in gluconeogenesis. FBP is regulated in several ways and is sensitive to both inhibitors and activators. A research team investigating potential therapies for type 2 diabetes has identified FBP as a therapeutic target. To treat type 2 diabetes, should the team focus on FBP inhibitors or activators, and why?

A

FBP inhibitors; to decrease gluconeogenesis and glucose levels

148
Q

Glucose-6-phosphatase is an enzyme that removes the phosphate group from glucose-6-phosphate to produce glucose, a key step in gluconeogenesis. What are the primary locations where glucose-6-phosphate is expressed in the body?

A

Liver, kidneys, small intestine

149
Q

Insulin stimulates glycolysis and represses gluconeogenesis, resulting in the consumption of glucose to produce energy in the form of ATP. If a pregnant mother develops gestational diabetes and insulin resistance, what would be the effect on gluconeogenesis and glucose availability to the fetus?

A

Gluconeogenesis would increase, making more glucose available

150
Q

What is the first enzyme in the glycolysis path?

A

Hexokinase

151
Q 
Which of the following are intermediate component(s) of glycolysis? Select all that apply.
A. 1,3-Biphosphoglycerate
B. alpha-ketoglutarate
C. Isocitrate
D. Phosphoenolpyruvate
E. Uridine diphosphate glucose
A

A. 1,3-Biphosphoglycerate

D. Phosphoenolpyruvate

152
Q

In the process of glycolysis, after glucose is phosphorylated into glucose 6-phosphate (G6P), it is isomerized into fructose 6-phosphate (F6P) by what enzyme?

A

Glucose phosphate isomerase

153
Q

Glycolysis is the process of converting the six-carbon molecule glucose into two three-carbon molecules, generating ATP and NADH. What three-carbon molecule is the final product of glycolysis?

A

Pyruvate

154
Q

Pancreatic ductal adenocarcinoma is a highly lethal form of cancer that thrives in environments with little nutrients; research to elucidate how these cells adapt to metabolic stress is of interest. A microRNA that downregulates phosphofructokinase has been identified in these cells. What would be inhibited by this inhibition of phosphofructokinase?

A

Glycolysis

155
Q

In some cancer types, the glycolytic enzyme hexokinase is upregulated in the tumor tissue compared to healthy tissues. Hexokinase expression levels may increase in more advanced stages of cancer. Hexokinase catalyzes the first step of glycolysis. Why is upregulated hexokinase an important advantage for a tumor cell?

A

Hexokinase produces glucose-6-phosphate, which cannot escape from the cell

156
Q

What chemical reaction takes place when two carbohydrate molecules bond together to form one molecule?

A

Condensation

157
Q

What type of reaction joins two monosaccharides to make a disaccharide?

A

Dehydration

158
Q

What depiction of carbohydrates can clearly illustrate stereochemistry at each carbon center?

A

Fischer projection

159
Q

What characteristic defines the naming convention based on glyceraldehyde enantiomers?

A

Position of the alcohol group relative to the chiral center

160
Q

Which class of carbohydrates are furanoses and pyranoses?

A

Cyclic monosaccharides

161
Q

Pyruvate dehydrogenase is the enzyme that converts pyruvate to acetyl CoA, which combines with oxaloacetate to form citrate in the TCA cycle. Hypoxia-inducing factors (HIFs) are transcription factors that are activated in many tumors. HIFs have been shown to activate pyruvate dehydrogenase kinase, which is a negative regulator of pyruvate dehydrogenase. What is the result of HIFs on the TCA cycle?

A

Inhibiting the TCA cycle

162
Q

Isocitrate dehydrogenase (IDH) is a key enzyme in the citric acid cycle frequently involved in various cancers. Several IDH inhibitors are being developed as potential cancer treatments. What inhibits this enzyme in the citric acid cycle?

A

ATP

163
Q

Why is oxygen needed for aerobic respiration in the Krebs cycle?

A

Electron transport chain

164
Q

What is the final metabolite in the Krebs cycle that joins again to start the cycle?

A

Oxaloacetate

165
Q

What compound is required to enter the Krebs cycle in an oxygen-rich environment?

A

Acetyl-CoA

166
Q

What kind of process is the citric acid cycle?

A

Amphibolic

167
Q

Where does the citric acid cycle occur in eukaryotes?

A

Mitochondria

168
Q

Acetyl CoA undergoes oxidation in the Krebs cycle. Three molecules of which product of this process enter the electron transport chain?

A

NADH

169
Q

Succinyl-CoA is formed during the Krebs cycle. What enzyme catalyzes its formation?

A

Alpha-ketoglutarate dehydrogenase

170
Q

An enzyme catalyzes the oxidative decarboxylation of isocitrate. What stimulates the activity of this enzyme?

A

ADP

171
Q

An enzyme catalyzes the oxidative decarboxylation of isocitrate. What inhibits this enzyme?

A

ATP

172
Q

An enzyme catalyzes the oxidative decarboxylation of isocitrate. What enzyme catalyzes the step prior to this reaction?

A

Aconitase

173
Q

Acetyl CoA enters the Krebs cycle. What enzyme acts upon it in the first step of this process?

A

Citrate synthase

174
Q

An anabolic process results in the formation of glucose from fat and protein substrates. What reaction is occurring?

A

Gluconeogenesis

175
Q

What hormone decreases gluconeogenesis?

A

Insulin

176
Q

A period of fasting, lasting more than 2 days, has led to low blood sugar levels. What substrate will be most used to generate glucose?

A

Pyruvate

177
Q

A short period of fasting triggers glucagon secretion and glycogen phosphorylase activation. What catabolic process will occur as a result?

A

Glycogenolysis

178
Q

A catabolic process results in the formation of glucose-1-phosphate from glycogen. What hormone upregulates this process?

A

Epinephrine

179
Q

An increase in blood glucose levels following digestion of a meal causes insulin secretion. What will occur next to reduce excess glucose in the blood?

A

Enhancement of cell proliferation

180
Q

A reductase inside complex III accepts electrons from a carrier of complex II. What accepts these electrons next?

A

Cytochrome C

181
Q

Flavin adenine dinucleotide (FAD) accepts two electrons inside complex II of the electron transport chain. What accepts these electrons after FAD transfers them to Fe-S clusters?

A

Coenzyme Q

182
Q

Glucose enters a series of reactions that transfers some of the energy from it to ADP. Which product of this process enters the electron transport chain?

A

NADH

183
Q

What is produced during the investment phase of glycolysis?

A

Glucose-6 phosphate

184
Q

What respiratory enzyme is also known as complex I in the electron transport chain?

A

NADH dehydrogenase

185
Q

Where does the majority of oxidative phosphorylation occur in the cell?

A

Mitochondria

186
Q

During which stage(s) of cell respiration is NADP (nicotinamide adenine dinucleotide phosphate) created?

A

Glycolysis and the Krebs cycle

187
Q

Tigecycline is an antibiotic that inhibits mitochondrial oxidative phosphorylation; it shows promise for treating many types of cancers. How would you expect tigecycline to affect ATP and energy levels of a cell?

A

Decrease both ATP and energy

188
Q

To carry out oxidative phosphorylation, an electrochemical gradient must be established and maintained. The proteins involved in maintaining this electrochemical gradient may present a therapeutic target for acute myeloid leukemia. Where in the cell is this electrochemical gradient maintained, and where would therapies aimed at this system need to be targeted?

A

Inner mitochondrial membrane

189
Q

What biochemical process is responsible for the buildup of compounds by use of ATP energy?

A

Anabolism

190
Q

Oxidation-reduction reactions always occur together. Electrons are shared between these reactions. What happens to the oxidation side of the reaction?

A

Electrons are lost

191
Q

What stage in the oxidation of foodstuffs involves the release of energy in the form of ATP from NADH and FADH2?

A

Tertiary metabolism

192
Q

Where is the mitochondrial electron transport chain/respiratory chain located?

A

Inner mitochondrial membrane

193
Q

What type of pyridine nucleotide redox system is responsible for the generation of nitric oxide?

A

Nicotinamide adenine dinucleotide phosphate

194
Q

What molecule is the strongest oxidizing agent?

A

Ubiquinone

195
Q

What type of pyridine nucleotide redox system plays an important role in apoptosis?

A

Nicotinamide adenine dinucleotide

196
Q

ATP is most often used within the cell. What ATP function occurs outside the cell?

A

Inflammation

197
Q

Which process to create ATP occurs in chloroplasts?

A

Photosynthesis

198
Q

Where does ATP synthesis occur in a human body cell?

A

Cytoplasm and mitochondria

199
Q

Where in the mitochondria is pyruvate converted into acetyl CoA?

A

Matrix

200
Q

What process gets its energy from ATP synthase localized to plasma membranes?

A

Development of malignancy

201
Q

What process provides the energy typically used for ADP phosphorylation?

A

Oxidative metabolism

202
Q

Enhanced glucose levels induce a mitochondrial process and play a role in the pathophysiology of type 2 diabetes. Which process is thought to contribute through insulin resistance?

A

Oxidative phosphorylation

203
Q

Pyruvate is converted to NADH, FADH2, and GTP. Where does this process take place with respect to the mitochondria?

A

Matrix

204
Q

A glucose molecule is split into two pyruvate molecules. Where does this process take place with respect to the mitochondria?

A

Cytosol

205
Q

In which part of the mitochondria are proteins of the electron transport chain located?

A

Inner membrane

206
Q

Where are hydrogen ions deposited inside the mitochondria?

A

Intermembrane space

207
Q

What is produced during lypolisis and enters gluconeogenesis?

A

Glycerol

208
Q

What is produced through beta-oxidation during lipolysis?

A

Acetyl CoA

209
Q

A metabolic process occurs to enable the human body to obtain the maximum amount of energy from proteins during a period of starvation. What is produced by deamination of glutamate during this process?

A

Alpha-ketoglutarate

210
Q

Which enzyme of the Krebs cycle facilitates production of FADH2?

A

Succinate dehydrogenase

211
Q

Which enzyme of the Krebs cycle facilitates formation of GTP?

A

Succinate thiokinase

212
Q

Which enzyme of the Krebs cycle facilitates that combination of acetyl CoA and oxaloacetate?

A

Citrate synthase

213
Q

What type of cells exhibits altered glucose levels upon treatment with an insulin receptor antagonist?

A

Myoblasts

214
Q

The concentration of hydrogen ions [H+] in a solution is 1 x 10-7 moles/L. What is the pH of the solution?

A

7 (pH can be calculated as; pH = -log[H+]

215
Q

What characteristic is associated with eicosanoids?

A

Mediation of fever

216
Q

A 25-year-old patient presents with severe pain in the groin area and describes sighting blood in the urine. The patient reports no recent trauma, has a negative sexual history, and has not previously experienced these symptoms. What condition may be responsible for the patient’s reported symptoms?

A

Cystinuria

217
Q

An increased risk of hemorrhaging can be attributed to a deficiency in what vitamin?

A

Vitamin K

218
Q

Vitamin B6 is involved in what function in humans?

A

Vitamin B6 helps in letting amino acids and Na+ out from the cell against a concentration gradient.

219
Q

What vitamin deficiency is responsible for irreversible damage to the brain and the nervous system?

A

Cobalamin (B12)

220
Q

The conversion of phenylalanine to tyrosine is catalyzed by what?

A

Phenylalanine hydroxylase

221
Q

Research into polymers that inhibit insulin aggregation is important in the treatment of diabetes mellitus. These polymers are added to denatured insulin to help it regain its function. What does this indicate about the denaturation of insulin?

A

The denaturation of insulin is reversible

222
Q

Birth defects, macrocytic anemia, and elevated homocysteine levels in the body are caused by a deficiency of what vitamin?

A

B9

223
Q

The citric acid cycle is part of cellular respiration, breaking down glucose into energy the cell can use. The citric acid cycle also provides precursors for biosynthesis of fatty acids, amino acids, and other biomolecules. What kind of process is the citric acid cycle?

A

Amphibolic

224
Q

Cholesterol oxidase is an enzyme that catalyzes the oxidation and isomerization of cholesterol. Cholesterol oxidase may have applications in synthesizing medicines, in the food industry, and as an insecticide. Using a Lineweaver-Burk plot, the Km was estimated to be 31 μM, with a Vmax of approximately 29 μmol/min/mL.

What would you expect the initial velocity of this reaction to be with a substrate concentration of 1 μM?

A

0.9 μmol/min/mL

225
Q

The Notch signaling pathway is critical in development and cancer. Post-translational modifications are a key way the activity and output of this signaling pathway can be fine-tuned. Phosphorylation of the intracellular domain of Notch generally increases its ubiquitination and marks it for proteasomal degradation. Phosphatase Eya1 acts on a specific threonine residue in the Notch intracellular domain.

How would enhanced Eya1 activity affect Notch stability and Notch signaling?

A

Increased Notch stability, increased Notch signaling

226
Q

In a 60-year-old patient with liver cirrhosis, detoxification of ammonia is impaired and damaging the brain. Which of the following can transport ammonia in a non-toxic form?

A

Glutamine

227
Q

Hydrolysis of what bond releases energy from the ATP molecule?

A

Phosphoanhydride bond

228
Q

Which of the following hemolytic anemias is due to an inborn error of metabolism?

A

Glucoso-6 phosphate dehydrogenase deficiency

229
Q

After drinking a chocolate milk-based drink (sweetened with table sugar), what is/are the major carbohydrate product(s) that enter the blood after digestion?

A

Galactose, fructose, and glucose

230
Q

Adenosine triphosphatases (ATPases) are ion pumps that span the lipid bilayer. Like all proteins, ATPases are composed of many amino acids. Where would you expect to find the most isoleucine residues in an ATPase?

A

Interacting with the hydrophobic lipids

231
Q

Selenocysteine can only be incorporated into protein by recoding a UGA codon. This recoding requires a selenocysteine insertion sequence in the mRNA 3’UTR and the presence of what specific molecule?

A

The tRNA specific for selenocysteine

232
Q

Serine is necessary for the proper formation of the myelin sheath (fatty tissue that wraps around the axons of nerve cells).

What problems can be caused by serine synthesis disorders in newborns?

A

Hypomyelination and microcephaly

233
Q

How are polypeptide chains of silk fibroin, a fibrous protein, arranged?

A

ß-pleated sheets

234
Q

The oxidative phosphorylation system is highly regulated to provide the appropriate level of ATP needed in the cell. ATP synthase is less active when phosphorylated. A mutation of protein kinase C, the enzyme that phosphorylates ATP synthase, has been identified as more active than normal. What would you predict would be the effect of this mutated protein kinase C on ATP synthase activity and ATP levels in the cell?

A

Decreased ATP synthase activity and ATP levels

235
Q

The urea cycle takes place in the mitochondria of the liver, where excess ammonia is degraded into urea for excretion. In the initial step of the cycle, ammonia (along with bicarbonate and 2 molecules of ATP) is converted into which of the following molecules?

A

Carbamoyl phosphate

236
Q

How do the antiparallel beta sheets in the mature mammalian cystatin-related epididymal spermatogenic protein differ from the parallel beta sheets in the immature protein?

A

The amino end of one beta strand is aligned with the carboxyl end of the next beta strand

237
Q

For the reactions containing transaminases, which of the following is a common nitrogen acceptor?

A

α-ketoglutarate

238
Q

Glycolysis is the process of converting the six-carbon molecule glucose into two three-carbon molecules, generating ATP and NADH. What three-carbon molecule is the final product of glycolysis?

A

Pyruvate

239
Q

What explains anemia as a result of vitamin B6 deficiency?

A

The role of vitamin B6 in the production of delta-aminolevulinic acid

240
Q

What pattern of inheritance would be expected for individuals affected by glucose-6-phosphate dehydrogenase deficiency?

A

Mostly males will be affected

241
Q

Which cellular transporter is mostly responsible for transportation of vitamin C?

A

SVCT2

242
Q

In SDS-polyacrylamide gel electrophoresis (SDS-PAGE), proteins are separated based on what?

A

Molecular mass

243
Q

A 32-year-old man presents with severe muscle cramps. His laboratory result shows a deficiency of muscle glycogen phosphorylase. Which of the following is his most probable diagnosis?

A

McArdle’s disease

244
Q

What process is taking place when aspirin is used to reduce the activity of the enzyme responsible for inflammation?

A

Enzyme inhibition

245
Q

What enzyme is found in both the glycolysis pathway and the gluconeogenesis pathway?

A

Phosphoglucoisomerase

246
Q

Which of the following is a synthetic form of vitamin K?

A

Menadione

247
Q

What enzyme is used in both gluconeogenesis and glycolysis?

A

3-phosphoglycerate kinase

248
Q

Which intermediary of the cholesterol biosynthesis pathway plays an important role in protein prenylation?

A

Isopentenyl pyrophosphate

249
Q

A hospital lab indicates a urine sample pH of 5.0 in a patient presenting with symptoms of kidney stones. What is the actual hydrogen ion concentration of the urine sample?

A

10^-5 M

250
Q

Glycogen phosphorylase is the enzyme responsible for removing the terminal glucose residue from a glycogen chain, producing glucose-1-phosphate. Glycogen phosphorylase is activated by phosphorylation, which is carried out by the enzyme phosphorylase kinase. Glycogen phosphorylase has been investigated as a potential target for the treatment of type 2 diabetes. How would you expect a therapy for type 2 diabetes to affect this enzyme?

A

Effective therapy would dephosphorylate and inhibit glycogen phosphorylase.

251
Q

Polyphenols have anti-inflammatory properties and act in a variety of ways to exert these functions. They are known to inhibit enzymes that produce reactive oxygen species, and they upregulate endogenous antioxidant enzymes. Polyphenols have an effect on catalase.

What effect do polyphenols have on catalase, and why?

A

Polyphenols inhibit catalase because it degrades hydrogen peroxide

252
Q

Steroid hormones are synthesized from cholesterol, and some sex steroids can be converted into other sex steroids. In fact, the majority of estradiol in men is produced from testosterone in their fat tissue. What type of process converts estradiol to testosterone?

A

Aromatization

253
Q

What clinical condition can result from folic acid deficiency?

A

Macrocytic anemia

254
Q

Which of the following is a tryptophan-derived hormone?

A

Serotonin

255
Q

What form of zinc is present in shampoos for the treatment of seborrhoeic dermatitis?

A

Zinc pyrithione

256
Q

What vitamin B subtype is required as a precursor to coenzyme A?

A

Pantothenic acid (B5)

257
Q

DPP-4 inhibitors work by stimulating insulin secretion and inhibiting the secretion of what other pancreatic hormone?

A

Glucagon

258
Q

What is the term for the quantitive measure of the ability of a molecule to acquire electrons?

A

Reduction potential

259
Q

A patient presents with poor wound healing, bleeding gums, and petechiae. Which of the following vitamins may be deficient?

A

Vitamin C

260
Q

Howship’s lacunae are a feature of what?

A

Osteoclasts

261
Q

Cyclin-dependent kinase 9 (CDK9) is a key metabolic regulator and a candidate drug target for several types of cancer. CDK9 inhibitors have been shown to decrease the ability of prostate cancer cells to metabolize glucose, instead making them dependent on alternative energy sources. Given in combination with a CDK9 inhibitor, what would you predict would be lethal to prostate cancer cells?

A

Fatty acid oxidation inhibitors

Biochemistry PA-CAT Review (1 decks)

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