IPS 1 - BIOCHEM REVIEW QUES

To recognize sugars to defend against bacteria.

What is the function of the lectins found in plants?

● To act as a structural component of the cell wall.

● To synthesize carbohydrates from amino acids.

● To store energy in the form of starch.

● To recognize sugars to defend against bacteria.

To transport oxygen to body cells and remove waste

Which of the following is a function of blood, according to the document?

● To transport oxygen to body cells and remove waste

● To provide structural support for the body.

● To produce hormones.

● To store fat-soluble vitamins.

Diabetes mellitus

Which of the following is described as a disease related to carbohydrate metabolism in the provided text?

● Phenylketonuria (PKU)

● Anemia

● Diabetes mellitus

● Thrombocytopenia

It is the most common form found under physiologic conditions

Which of the following accurately describes a characteristic of the B-form of DNA, as mentioned in the

document?

● It contains 12 base pairs per turn

● It is similar to the B form but more compact

● It is the most common form found under physiologic conditions

● It is left-handed and has its bases positioned toward the periphery

● DNA with lots of A and T bases separates at a lower temperature than DNA with many G and C bases.

In prokaryotic cells, which enzyme is primarily responsible for most of the DNA copying during replication?

● The melting temperature is dependent on the length of the DNA molecule, but not its base composition.

● DNA with a high percentage of G and C bases has a lower Tm.

● DNA with lots of A and T bases separates at a lower temperature than DNA with many G and C bases.

● The melting temperature is unrelated to base composition.

They are found in damaged lipoproteins and contribute to atherosclerosis.

Which of the following is a role of lysophospholipids in the human body, according to the document?

● They are found in damaged lipoproteins and contribute to atherosclerosis.

● They are the main component of lung surfactant.

● They help with nerve signal transmission.

● They act as a precursor for sex hormones.

By using sound waves to break up amphipathic lipids in water.

The document explains that liposomes can be used to carry drugs and genes. How are they formed?

● By using sound waves to break up amphipathic lipids in water.

● By mixing fatty acids with cholesterol.

● By creating a micelle with a hydrophobic interior.

● By heating amphipathic lipids in water.

To hold the amino acid.

What is the function of the CCA sequence at the 3' end of a tRNA molecule?

● To act as the anticodon.

● To bind to the ribosome.

● To form the D loop.

● To hold the amino acid.

Small circular DNA molecules outside the chromosome that can copy themselves

The document describes plasmids in prokaryotic cells. Which of the following is an accurate description of a

plasmid?

● Histone proteins that DNA wraps around.

● A single, large chromosome in eukaryotic cells.

● Small, circular DNA molecules outside the chromosome that can copy themselves.

● A large, linear DNA molecule that is the main chromosome.

DNA polymerase I

What is the process that removes the RNA primer and replaces it with the proper DNA nucleotides to fill the

gap during DNA replication?

● DNA Ligase

● DNA polymerase III

● DNA Primase

● DNA polymerase I

Sulfur-containing amino acids

The formation of a black precipitate when a substance is treated with lead acetate indicates the presence of

which type of amino acid?

● Sulfur-containing amino acids

● Hydroxyl-containing amino acids

● Basic amino acids

● Aromatic amino acids

Grease Spot Test

A translucent spot left on a piece of paper after a substance is applied and dried indicates a positive result

for which test?

● Saponification Test

● Grease Spot Test

● Acrolein Test

● Sudan III/IV Test

To protect red blood cells from damage caused by certain chemicals.

What is the function of the enzyme G6PD (glucose-6-phosphate dehydrogenase)?

● To cause the breakdown of hemoglobin.

● To protect red blood cells from damage caused by certain chemicals.

● To produce red blood cells.

● To help blood clot.

Kwashiorkor

Which disease is described in the document as a severe lack of protein, even if calories are sufficient?

● Kwashiorkor

● Marasmus

● Diabetes mellitus

● Galactosemia

To link monosaccharide units together.

What is the purpose of the glycosidic bond in carbohydrates?

● To make the sugar hydrophobic.

● To reduce an aldehyde group to an alcohol.

● To link monosaccharide units together.

● To form a straight-chain structure.

To transport oxygen to body cells and remove waste.

Which of the following is a function of blood?

● To produce hormones.

● To store fat-soluble vitamins.

● To provide structural support for the body.

● To transport oxygen to body cells and remove waste.

It is the first antibody produced in response to an infection.

According to the document, what is the main function of the pentameric antibody (IgM)?

● It mediates allergic reactions and protects against parasitic infections.

● It is the first antibody produced in response to an infection.

● It is the most abundant antibody, providing long-term immunity.

● It provides localized protection at mucosal surfaces.

Glycolipids

Which of the following complex lipids is defined by the document as being made of a fatty acid, sphingosine,

and a sugar?

● Glycerophospholipids

● Phosphoacylglycerols

● Glycolipids

● Sphingophospholipids

Liver glycogenolysis provides glucose to the bloodstream to maintain blood sugar, whereas muscle

glycogenolysis provides energy for the muscle's own use during intense activity.

Which of the following statements correctly describes a difference in the regulation of glycogenolysis

between the liver and muscle cells, as mentioned in the provided information?

● Liver glycogenolysis provides glucose to the bloodstream to maintain blood sugar, whereas muscle

glycogenolysis provides energy for the muscle's own use during intense activity.

● Liver glycogenolysis is initiated by phosphorylase, but muscle glycogenolysis uses a different enzyme, acid

alpha-glucosidase.

● Glycogenolysis is inhibited when glycogenesis occurs in the liver but not in muscle tissue.

● Liver glycogenolysis is primarily stimulated by adrenaline, while muscle glycogenolysis is regulated by insulin.

Hexokinase, phosphofructokinase, pyruvate kinase

The "irreversible" steps of glycolysis, which are bypassed during gluconeogenesis, are catalyzed by which

of the following sets of enzymes?

● Triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate mutase

● Aldolase, phosphoglycerate kinase, enolase

● Pyruvate carboxylase, PEP carboxykinase, glucose-6-phosphatase

● Hexokinase, phosphofructokinase, pyruvate kinase

Acetyl-CoA, which is used by the Krebs cycle.

In the process of β-oxidation, what is the final product and its destination in the Krebs cycle?

● Ketone bodies, which are produced when the Krebs cycle is overloaded.

● Pyruvate, which is converted to acetyl-CoA for the Krebs cycle.

● Acetyl-CoA, which is used by the Krebs cycle.

● Fatty acids, which are directly used in the Krebs cycle.

DNA → RNA → Protein

What is the "central dogma of molecular biology"?

● Transcription → Translation → Replication

● DNA → RNA → Protein

● ATP → ADP → AMP

● Carbohydrates → Lipids → Proteins

● Hexokinase has a high affinity for glucose and is active in states of low blood glucose, while glucokinase has a low affinity and is utilized in high-glucose states.

Which of the following is a key regulatory difference between hexokinase and glucokinase?

● Glucokinase is used to phosphorylate glucose for entry into glycolysis, whereas hexokinase directs glucose

into glycogenesis.

● Hexokinase has a high affinity for glucose and is active in states of low blood glucose, while glucokinase has

a low affinity and is utilized in high-glucose states.

● Hexokinase is primarily found in the liver, while glucokinase is in most other tissues.

● Glucokinase is inhibited by its product, glucose-6-phosphate, while hexokinase is not.

Debranching enzyme

A specific enzyme in glycogenolysis is responsible for the hydrolysis of α1→6 linkages. What is the name of

this enzyme?

● Glycogen synthase

● Glycogen phosphorylase

● Debranching enzyme

● Phosphoglucomutase

Phosphofructokinase (PFK)

In a situation of high ATP levels, which key regulatory enzyme of glycolysis is allosterically inhibited, leading

to a decrease in its activity?

● Pyruvate Kinase (PK)

● Hexokinase

● Phosphofructokinase (PFK)

● Enolase

A glycogen storage disease

A patient is found to have a buildup of glucose storage in their liver and muscles, leading to a metabolic

disorder. This is most likely an example of:

● Galactosemia

● Diabetes mellitus

● A glycogen storage disease

● Lactose intolerance

To be a glycoprotein in human red blood cell membranes.

What is the primary function of Glycophorin?

● To be a glycoprotein in human red blood cell membranes.

● To act as a plant lectin to defend against bacteria.

● To serve as an antibody to protect against infections.

● To aid in the synthesis of glycoproteins.

The bonds closest to the viewer are drawn as bold and thick.

Which of the following is a key characteristic of the Haworth projection for cyclic glucose?

● It shows the molecule from a top-down view.

● The bonds closest to the viewer are drawn as bold and thick.

● All hydrogen atoms are explicitly drawn.

● It shows the true three-dimensional chair shape of the ring.

They are linked to the misfolding of soluble protein clumps.

Which of the following statements about prion diseases is true?

● They are linked to the misfolding of soluble protein clumps.

● They are caused by a virus.

● They are always found in humans, but not animals.

● They are treated with antibiotics.

Africa, the Mediterranean, and Southeast Asia

A deficiency in a specific enzyme can cause red blood cells to burst when exposed to certain chemicals. This

inherited condition is most common in people from which regions?

● South America and Australia

● North America and Europe

● East Asia and Russia

● Africa, the Mediterranean, and Southeast Asia

By using sound waves to break up amphipathic lipids in water.

Liposomes can be used to carry drugs and genes. How are they formed?

● By using sound waves to break up amphipathic lipids in water.

● By creating a micelle with a hydrophobic interior.

● By mixing fatty acids with cholesterol.

● By heating amphipathic lipids in water.

Hydrogen bond, which dictates complementary base pairing

A particular type of bond is responsible for the strong linkage between DNA helices. Which type of bond is

this, and what is its primary significance?

● Phosphodiester bond, which links nucleotide groups

● Hydrogen bond, which dictates complementary base pairing

● Covalent bond, which is a strong linkage between DNA helicases

● Glycosidic bond, which links a sugar and a nitrogen base

To relieve torsional strain by cutting and rejoining DNA strands

What is the role of Topoisomerase during DNA replication, as described in the provided text?

● To relieve torsional strain by cutting and rejoining DNA strands

● To unwind the DNA helix at the replication fork

● To synthesize a short RNA primer for DNA polymerase

● To add new DNA nucleotides to the RNA primer

It initiates the synthesis of RNA primers.

What is the function of the enzyme DNA primase in DNA replication?

● It relieves torsional strain in the DNA helix.

● It unwinds the DNA helix.

● It joins Okazaki fragments on the lagging strand.

● It initiates the synthesis of RNA primers.

The codon containing the changed base codes for a different amino acid.

A change in a single nucleotide base in a DNA sequence can result in a missense mutation. According to the

document, what is the outcome of a missense mutation?

● The codon containing the changed base becomes a termination (stop) codon.

● The genetic code is no longer nonoverlapping and commaless.

● The codon containing the changed base codes for a different amino acid.

● The codon containing the changed base codes for the same amino acid.

To protect the mRNA from degradation and aid in its translation.

What is the main function of the poly(A) tail on a eukaryotic mRNA molecule?

● To serve as an anticodon for tRNA.

● To act as a start codon for protein synthesis.

● To attach a modified guanine to the start of the mRNA.

● To protect the mRNA from degradation and aid in its translation.

The template strand moves from 3' to 5', and the pre-mRNA moves from 5' to 3'.

What is the correct reading direction for the template strand of DNA and the newly synthesized mRNA

molecule during transcription in a eukaryotic cell?

● Both the template strand and the pre-mRNA move from 3' to 5'.

● The template strand moves from 3' to 5', and the pre-mRNA moves from 5' to 3'.

● The template strand moves from 5' to 3', and the pre-mRNA moves from 3' to 5'.

● Both the template strand and the pre-mRNA move from 5' to 3'.

To unwind the double-stranded DNA by pulling the strands apart.

What is the role of helicase during DNA replication?

● To unwind the double-stranded DNA by pulling the strands apart.

● To synthesize a short RNA primer to initiate DNA synthesis.

● To join Okazaki fragments together on the lagging strand.

● To relieve the positive supercoils that form ahead of the replication fork.

DNA polymerases

Which type of enzyme is responsible for the polymerization of deoxynucleotides?

● DNA polymerases

● Helicases

● DNA ligase

● DNA primase

It undergoes apoptosis (programmed cell death).

What happens to a cell that has DNA damage that is too extensive to be repaired?

● It undergoes a silent mutation.

● It converts the damage into a harmless substance.

● It enters the G0 resting phase.

● It undergoes apoptosis (programmed cell death).

The codon containing the changed base codes for the same amino acid.

What is the correct definition of a silent mutation as presented in the document?

● The codon containing the changed base codes for the same amino acid.

● There is no change to the DNA sequence.

● The codon containing the changed base becomes a termination codon.

● The codon containing the changed base codes for a different amino acid.

It is a structure where DNA is wrapped around a group of eight histone proteins

Which of the following best describes the beads on a string nucleosomal structure of chromatin?

● It is a linear chain of polynucleotides without any associated proteins.

● It is the most compact form of DNA packaging.

● It is a structure where DNA is found in the nucleus, mitochondria, and chloroplasts.

● It is a structure where DNA is wrapped around a group of eight histone proteins

Seliwanoff's Test

A test that differentiates ketoses from aldoses by forming a cherry red color is known as:

● Seliwanoff's Test

● Benedict's Test

● Bial's Test

● Barfoed's Test

Protein synthesis

The process where a cell creates proteins is described as being at the core of the "central dogma of

molecular biology." What is this process called?

● Transcription

● DNA replication

● Protein synthesis

● Translation

It is a precursor for vitamin D.

Which of the following is a function of cholesterol mentioned in the document?

● It is a component of bacterial cell membranes.

● It helps in the biosynthesis of glycoproteins.

● It serves as a primary source of stored energy.

● It is a precursor for vitamin D.

T-cells and natural killer cells

A plant lectin called Concanavalin A can activate which of the following immune cells, according to the

document?

● Macrophages

● B-cells

● Mast cells

● T-cells and natural killer cells

Liver glycogenolysis provides glucose to the bloodstream to maintain blood sugar, whereas muscle

glycogenolysis provides energy for the muscle's own use during intense activity.

Which of the following statements correctly describes a difference in the regulation of glycogenolysis

between the liver and muscle cells?

● Liver glycogenolysis is initiated by phosphorylase, but muscle glycogenolysis uses a different enzyme, acid

alpha-glucosidase.

● Liver glycogenolysis is primarily stimulated by adrenaline, while muscle glycogenolysis is regulated by

insulin.

● Liver glycogenolysis provides glucose to the bloodstream to maintain blood sugar, whereas muscle

glycogenolysis provides energy for the muscle's own use during intense activity.

● Glycogenolysis is inhibited when glycogenesis occurs in the liver but not in muscle tissue.

Lysozyme

Select the enzyme that hydrolyzes bacterial cell walls.

● Lactate dehydrogenase

● Kinase

● Lysozyme

● Carbonic anhydrase

Norepinephrine, Epinephrine, Dopamine

The amino acid Tyrosine is converted to catecholamines. These are:

● Norepinephrine and Epinephrine

● Epinephrine, Dopamine

● Norepinephrine, Epinephrine, Dopamine

● Norepinephrine, Dopamine

IgG

The most abundant of the serum immunoglobulins is:

● IgA

● IgM

● IgE

● IgG

The release of fatty acids and their subsequent beta-oxidation is a primary source of metabolic energy for the cell.

Which of the following statements best describes fatty acid metabolism?

● Fatty acid catabolism is not under hormonal control

● Fatty acids and their CoA esters can freely cross the inner mitochondrial membrane.

● Fatty acid metabolism is not related to carbohydrate metabolism.

● The release of fatty acids and their subsequent beta-oxidation is a primary source of metabolic energy for the cell.

Achievement of a high absolute rate of reaction that is suitable for integration with other physiological processes.

Analyze the mechanism or catalytic strategy employed by carbonic anhydrase.

● Promotion of a reaction that is immeasurably slow at neutral pH.

● Attainment of a high degree of specificity

● Utilization of the free energy associated with the hydrolysis of ATP

● Achievement of a high absolute rate of reaction that is suitable for integration with other physiological processes

Glycerol, lactate, pyruvate, glycogenic amino acids

Identify the precursors of gluconeogenesis

● Sucrose, lactic acid, pyruvic acid

● Glycerol, lactic acid, pyruvic acid

● Pyruvic acid, lactic acid, acetic acid

● Glycerol, lactate, pyruvate, glycogenic amino acids

Citric Acid

Select the carbohydrate used as an acidulant, especially in infant feeding formulas:

● Citric Acid

● Mannitol

● Lactic Acid

● Tartaric Acid

Codon from mRNA

Determines amino acid sequence:

● Codon from mRNA

● Anticodon from tRNA

● Peptide bond

● Codon from DNA

Stereoisomers that differ in configuration at one specific carbon atom

Epimers are:

● Stereoisomers that differ in configuration at one specific carbon atom

● Structural isomers

● Monosaccharides

● Enantiomers

Substitution

Nucleotide sequence —> identify type of mutation:

● Substitution

● No mutation

● Insertion

● Deletion

1-deoxy-D-xylulose-5-phosphate

Intermediate product of MEP that acts as a stress regulator:

● 1-deoxy-L-xylulose-5-phosphate

● Methylerythritol cyclodiphosphate

● 1-deoxy-D-xylulose-5-phosphate

● Isopentenyl diphosphat

Ubiquitin ligase (C-O)

Correct bonds formed by ligases:

● Acyl CoA synthetase (C-O)

● Ubiquitin ligase (C-O)

● Aminoacyl tRNA synthetase (C-S)

● Pyruvate carboxylase (C-C)

Prosthetic group

Which of the following terms BEST describes a cofactor that is firmly bound to an apoenzyme?

● Prosthetic group

● Holoenzyme

● Transferase

● Cofactor

Insulin

Compound that inhibits glycogenolysis:

● Glucagon

● Cortisol

● Insulin

● Epinephrine

Metabolic Syndrome

Which condition is characterized by a cluster of conditions including insulin resistance and hypertension?

● Glycogen Storage Diseases

● Diabetes Mellitus

● Metabolic Syndrome

● Lactose Intolerance

Cardiovascular disease

Chronic glycemia can lead to which of the following complications?

● Reduced blood pressure

● Enhanced kidney function

● Cardiovascular disease

● Improved immune function

Marasmus

Which condition results from severe energy deficiency and is characterized by weight loss and muscle

wasting?

● Cystic Fibrosis

● Sickle Cell Disease

● Marasmus

● Kwashiorkor

CFTR gene

Cystic Fibrosis is caused by mutations in which gene?

● APC gene

● BRCA1 gene

● CFTR gene

● HTT gene

Sickle Cell Disease

Which disease is caused by a mutation in the hemoglobin gene, leading to sickle shaped red blood cells?

● Anemia

● Sickle Cell Disease

● Thalassemia

● Hemophilia

Accumulation of fat in the liver unrelated to alcohol

Which of the following is a characteristic of Non-Alcoholic Fatty Liver Disease

(NAFLD)?

● Caused by hepatitis virus

● Accumulation of fat in the liver unrelated to alcohol

● Linked to autoimmune disorders

● Related to excessive alcohol consumption

CAG repeat expansion

Huntington's Disease is characterized by what type of genetic mutation?

● Translocation

● Deletion

● Point mutation

● CAG repeat expansion

Collagen

Ehlers-Danlos Syndrome is primarily linked to defects in which protein?

● Collagen

● Elastin

● Keratin

● Myosin

Glycogen has branched every 12-15 glucose units, while amylopectin has branched every 24-30 units.

Glycogen and Amylopectin are both branched polysaccharides. What is a key structural difference between

them?

● Amylopectin has more frequent branches than glycogen.

● Glycogen has α1→6 bonds, while amylopectin only has α1→4 bonds.

● Amylopectin is an animal starch, while glycogen is a plant starch.

● Glycogen has branched every 12-15 glucose units, while amylopectin has branched every 24-30 units.

A harmonious balance of biochemical reactions is the molecular basis for health, while abnormalities lead to

disease

Which of the following BEST describes the relationship between biochemistry and medicine?

● Biochemistry is a sub-discipline of medicine focused on laboratory diagnostics.

● Biochemical processes are only relevant for genetic diseases.

● Medicine is the application of biochemical principles to cure all diseases.

● A harmonious balance of biochemical reactions is the molecular basis for health, while abnormalities lead to

disease

The Cell, as it contains the organelles and enzymes that carry out metabolic pathways.

From a biochemical perspective, what is the most fundamental level in the hierarchy of li here the principles

of metabolism become evident

● The Tissue, as its a collection of specialized cells working together.

● The Organism, as it represents the sum total of all metabolic activity.

● The Molecule, as biomolecules are the reactants and products of metabolism.

● The Cell, as it contains the organelles and enzymes that carry out metabolic pathways.

The maintenance of cytosolic ion gradients.

A defect in the selective permeability of the plasma membrane would most immediately impact which cellular

process?

● The maintenance of cytosolic ion gradients.

● Protein synthesis at the ribosome.

● Lipid synthesis in the smooth endoplasmic reticulum.

● DNA replication in the nucleus.

Eukaryotes compartmentalize metabolic pathways within membrane-bound organelles, whereas prokaryotes do not

Which statement most accurately distinguishes prokaryotic cells from eukaryotic cells from a biochemical

standpoint?

● Prokaryotes use RNA as their genetic material, while eukaryotes use DNA.

● Prokaryotes lack ribosomes and thus cannot synthesize proteins.

● Eukaryotes compartmentalize metabolic pathways within membrane-bound organelles, whereas prokaryotes

do not

● Eukaryotic cells are the only cells that possess a plasma membrane.

The aggregation of nonpolar side chains minimizes their surface area, leading to a large increase in the

entropy of the surrounding water molecules.

Which of the following statements most accurately describes the thermodynamic basis for the hydrophobic

effect driving protein folding?

● The formation of strong van der Waals interactions between nopolar side chains releases a significant

amount of enthalpy.

● The polypeptide chain seeks a lower energy state by maximizing hydrogen bonds between polar side chains

and the aqueous solvent.

● Hydrogen bonding between water molecules is disrupted by nopolar solutes, creating an enthalpically

unfavorable state that is resolved by aggregation.

● The aggregation of nonpolar side chains minimizes their surface area, leading to a large increase in the

entropy of the surrounding water molecules.

Bicarbonate-carbonic acid buffer system (HCO, /H,CO,)

The polypeptide chain seeks a lower energy state by maximizing hydrogen bonds between polar side chains

and the aqueous solvent.

● Protein buffer system (e.g., hemoglobin )

● Phosphate buffer system (H2PO*/HPO,2 )

● Ammonia buffer system (NH./NH.*)

● Bicarbonate-carbonic acid buffer system (HCO, /H,CO,)

It is a competitive inhibitor, binding to the active site of the free enzyme

A novel enzyme is discovered that displays Michaelis-Menten kinetics. In the presence of Inhibitor X, the

apparent Km increases, but the Vmax remains unchanged. What can be concluded about Inhibitor X?

● It is an uncompetitive inhibitor, binding only to the enzyme-substrate complex.

● It is an irreversible inhibitor, forming a covalent bond with the enzyme.

● It is a competitive inhibitor, binding to the active site of the free enzyme

● It is a non-competitive inhibitor, binding to a site other than the active site.

They are anomers, differing only in the configuration of the hydroxyl group at the hemiacetal carbon (C-1).

Which of the following best describes the structural difference between an a-D-glucopyranose and a

B-D-glucopyranose?

● They are epimers at C-4, differing only in the configuration of the hydroxyl group at the fourth carbon.

● They are constitutional isomers, having the same molecular formula but a different connectivity of atoms.

● They are enantiomers, non-superimposable mirror images of each other

● They are anomers, differing only in the configuration of the hydroxyl group at the hemiacetal carbon (C-1).

Creation of a hydrophobic patch on the protein surface that interacts with a complementary patch on another deoxyhemoglobin molecule.

A point mutation in the gene for hemoglobin results in the substitution of a glutamate residue with a valine

residue on the beta-globin surface. This is the molecular basis of sickle cell anemia. What is the primary

driving force for the polymerization of deoxyhemoglobin S?

● Formation of a new disulfide bond between beta chains of adjacent hemoglobin tetramers.

● Loss of a negative charge, which disrupts ionic bonds that maintain the native tetramer structure.

● Creation of a hydrophobic patch on the protein surface that interacts with a complementary patch on another

deoxyhemoglobin molecule.

● An allosteric change that permanently locks the hemoglobin in the high-oxygen-affinity R-state.

To extend the 3' end of the linear chromosome using an internal RNA template, preventing chromosome

shortening.

During eukaryotic DNA replication, what is the primary function of the enzyme telomerase?

● To extend the 3' end of the linear chromosome using an internal RNA template, preventing chromosome

shortening.

● To remove the RNA primers and replace them with DNA nucleotides.

● To synthesize the RNA primers required for DNA polymerase to initiate synthesis on the lagging strand.

● To unwind the DNA double helix at the replication fork, creating single-stranded templates

Chylomicrons

Which lipoprotein is primarily responsible for transporting dietary triacylglycerols from the intestine to

peripheral tissues?

● Chylomicrons

● High-density lipoprotein (HDL)

● Very-low-density lipoprotein (VLDL)

● Low-density lipoprotein (LDL)

The pairing between the codon on mRNA and the anticodon on tRNA during translation.

The wobble hypothesis, proposed by Francis Crick, pertains to which molecular interaction?

● The pairing between the codon on mRNA and the anticodon on tRNA during translation.

● The splicing of introns from pre-mRNA by the spliceosome.

● The binding of transcription factors to promoter regions on DNA.

● The binding of DNA polymerase to the template strand during replication.

A decrease in the cellular synthesis of cholesterol, leading to an upregulation of LDL receptors.

Which of the following would be the most likely effect of a drug that acts as a non-competitive inhibitor of the

HMG-CoA reductase enzyme?

● An increase in the concentration of circulating VLDL particles.

● A decrease in the absorption of dietary cholesterol from the intestine.

● A decrease in the cellular synthesis of cholesterol, leading to an upregulation of LDL receptors.

● An increase in the synthesis of ketone bodies in the liver.

An alpha-helix

A peptide has the sequence: Asp-Arg-Val-Tyr-lle-His-Pro-Phe. In which of the following protein secondary

structures would the Proline (Pro) residue most likely disrupt or terminate the structure?

● A collagen triple helix

● A beta-sheet

● A beta-turn

● An alpha-helix

Addition of a 7-methylguanosine cap

The processing of a primary mRNA transcript in eukaryotes involves several modifications.

Which of these modifications is crucial for the initiation of translation by allowing the ribosome to recognize

and bind to the mRNA?

● Splicing of introns

● Addition of a poly(A) tail

● RNA editing by deamination

● Addition of a 7-methylguanosine cap

The affinity of hemoglobin for O2 decreases as pH decreases, facilitating O2 release in actively metabolizing tissues.

Which statement accurately describes the Bohr effect concerning hemoglobin?

● The affinity of hemoglobin for O2 decreases as pH decreases, facilitating O2 release in actively metabolizing

tissues.

● The quaternary structure of hemoglobin shifts from the T (tense) state to the R (relaxed) state upon release

of O2.

● The binding of 2,3-bisphosphoglycerate (2,3-BPG) to hemoglobin increases its affinity for O2.

● The binding of O2 to hemoglobin is enhanced by a decrease in pH and an increase in CO2 concentration.

Increase the nucleophilicity of the Ser-195 hydroxyl group, enabling it to attack the substrate's carbonyl

carbon.

In the mechanism of chymotrypsin, the role of the 'catalytic triad' (Ser-195, His-57, Asp-102) is to:

● Create a hydrophobic pocket that specifically recognizes and binds the substrate.

● Form a covalent bond with the N-terminal side of the scissile peptide bond.

● Increase the nucleophilicity of the Ser-195 hydroxyl group, enabling it to attack the substrate's carbonyl

carbon.

● Directly bind a zinc ion that polarizes the peptide bond, making it susceptible to hydrolysis.

Cellulose

Which of the following carbohydrates contains a B(1→4) glycosidic linkage that is indigestible by human

digestive enzymes?

● Sucrose

● Cellulose

● Amylopectin

● Maltose

Increasing the proportion of long-chain saturated fatty acids in the phospholipids.

The fluidity of a cell membrane is decreased by:

● Increasing the proportion of unsaturated fatty acids in the phospholipids.

● Increasing the temperature towards the higher end of the physiological range.

● Decreasing the cholesterol content at low temperatures.

● Increasing the proportion of long-chain saturated fatty acids in the phospholipids.

It recognizes and binds to specific promoter sequences (-10 and -35 boxes) in the DNA.

What is the primary role of the sigma (o) factor in bacterial transcription?

● It terminates transcription by recognizing a hairpin loop structure in the newly synthesized RNA.

● It unwinds the DNA double helix to create the transcription bubble.

● It catalyzes the formation of phosphodiester bonds in the growing RNA chain.

● It recognizes and binds to specific promoter sequences (-10 and -35 boxes) in the DNA.

Permanently inactive because it cannot be phosphorylated.

A scientist is studying a protein that is activated by phosphorylation. A mutation that changes the target

serine residue to an alanine would most likely result in a protein that is:

● Activated by a different mechanism, such as methylation.

● Unstable and rapidly degraded by the proteasome.

● Permanently inactive because it cannot be phosphorylated.

● Permanently active, regardless of the presence of the kinase.

pH 4.1

You are titrating a solution of the amino acid Histidine (pKa values: carboxyl ~2.2, imidazole ~6.0, amino

~9.2). At which pH would the molecule have, on average, a net charge of + 1?

● pH 4.1

● pH 10.0

● pH 1.0

● pH 7.6

Vmax = 2.0 nmol/min, Km = 0.5 mM

A Lineweaver-Burk plot for an enzyme-catalyzed reaction yields a line that intersects the y-axis at 0.5

(nmol/min)'' and the x-axis at -2.0 (mM)". What are the Vmax and Km for this reaction?

● Vmax = 0.5 nmol/min, Km = 0.5 mM

● Vmax = 0.5 nmol/min, Km = 2.0 mM

● Vmax = 2.0 nmol/min, Km = 0.5 mM

● Vmax = 2.0 nmol/min, Km = 2.0 mM

DNA Pol I possesses 5'→3' exonuclease activity, which is absent in DNA Pol III.

Which of the following describes a key difference between DNA Polymerase I and DNA Polymerase Ill in E. coli?

● DNA Pol I is the primary enzyme for chromosomal replication, while DNA Pol Ill is involved in nDNA repair.

● DNA Pol I possesses 5'→3' exonuclease activity, which is absent in DNA Pol III.

● DNA Pol Ill synthesizes DNA in the 3'→5' direction, unlike DNA Pol I.

● DNA Pol Ill has 3'→5' exonuclease activity, while DNA Pol I does not.

Quaternary structure

The structure of proteins can be analyzed at four levels. The association of multiple polypeptide chains into a

functional protein complex, such as in hemoglobin, represents which level of structure?

● Primary structure

● Quaternary structure

● Tertiary structure

● Secondary structure

Transfer RNA (RNA)

Which type of RNA is responsible for carrying a specific amino acid to the ribosome during the process of

translation?

● Ribosomal RNA (rRNA)

● Transfer RNA (RNA)

● Messenger RNA (mRNA)

● Small nuclear RNA (snRNA)

Dehydration synthesis (condensation) reaction

The formation of a peptide bond between two amino acids is an example of what type of reaction?

● Isomerization reaction

● Dehydration synthesis (condensation) reaction

● Oxidation-reduction reaction

● Hydrolysis reaction

Hydrophobic interactions

Which of the following forces is the most significant contributor to the stabilization of the tertiary structure of

a globular protein in an aqueous environment?

● Hydrophobic interactions

● Hydrogen bonds

● Disulfide bonds

● lonic bonds (salt bridges)

Vitamin B3 (Niacin) - NAD+ → Electron transfer (redox) reactions

Which of the following correctly pairs a vitamin with its active coenzyme form and the general type of

reaction it is involved in?

● Vitamin B12 (Cobalamin) - Tetrahydrofolate → One-carbon transfers

● Vitamin B1 (Thiamine) - FAD → Oxidation-reduction reactions

● Vitamin B3 (Niacin) - NAD+ → Electron transfer (redox) reactions

● Vitamin B6 (Pyridoxine) → Coenzyme A → Acy group transfer

Base stacking interactions, which are hydrophobic and van der Waals forces between adjacent bases.

The DNA double helix is stabilized by several forces. Which of the following contributes the most to the

thermodynamic stability of the helix in an aqueous solution?

● Base stacking interactions, which are hydrophobic and van der Waals forces between adjacent bases.

● The phosphodiester bonds of the sugar-phosphate backbone.

● Repulsion between the negatively charged phosphate groups on the backbone.

● Hydrogen bonds between complementary base pairs (A-T and G-C)