Biochem OA

A patient presents with a fever of 110°F. Which interaction(s) would be disrupted within a neuronal protein if the fever is not resolved quickly?

'hydrophobic interactions'. The patient's temperature is much higher than normal. High temperatures disrupt hydrophobic interactions. Hydrogen bonds are stronger interactions than hydrophobic interactions and will not be easily disrupted by heat as hydrophobic interactions will.

The negatively charged amino acid, Glutamate, is replaced with the negatively charged amino acid Aspartate. Which level of protein structure is most significantly impacted by this change?

'primary structure'. The original and substitute amino acid both have a negative charge and can both form an ionic bond with a positively charged amino acid. The amino acid sequence, however, has been altered, and so the primary structure has certainly been changed. Contributions to quaternary and tertiary structure, which are dependent on side-chain interactions, are most likely unaffected as both aspartate and glutamate can form ionic bonds with positively charged amino acid side chains.

Assuming 100% reaction efficiency, how many DNA copies are created after the completion of four complete PCR cycles?

16

How many ATP molecules are used in the conversion of pyruvate to glucose?

6

How many molecules of acetyl-CoA will the following fatty acid produce?

8

What occurs during the biochemical process of glycation?

A covalent bond forms between a sugar and a protein or lipid

Which of the following could be a potential ramification of a defective nucleotide excision repair (NER) pathway?

A defective nucleotide excision repair pathway would not be able to repair thymine dimers. The accumulation of thymine dimers would increase the probability of developing skin cancer.

In which situation would altering a protein structure lead to a disease state?

A mutation in aconitase blocks an essential step in aerobic metabolism

Which situation would most likely lead to a permanent alteration of protein function?

A mutation that substitutes a hydrophobic amino acid with a hydrophilic amino acid

Acetylcholine is broken down to acetate and choline by an enzyme called acetylcholinesterase. Low levels of acetylcholine in the brain is associated with neurodegenerative disease. Which of the following medications

A non-competitive inhibitor of acetylcholinesterase.

What occurs in an otherwise healthy person whose diet has very few carbohydrates and high levels of fats?

Acetone is produced in the blood.

Which molecule is pyruvate directly converted to under aerobic conditions?

Acetyl-CoA

What occurs during the process of alternative splicing of mRNA?

Alternate combinations of exons within the same gene are linked together.

Which of the following best describes the nature of protein primary structure?

Amino acids linked together in a specific order by peptide bonds

Primary structure consists of the order of ______ in a protein. These are held together with _______ bonds that are formed by a ________ reaction

Amino acids, peptide, dehydration. Protein primary structure is defined by the order of amino acids that make up the protein. The amino acids are linked together by peptide bonds, which are formed via dehydration reactions. While amino acids are held together by peptide bonds, these bonds are formed through a dehydration reaction, not a hydrolysis reaction.

Amylose, a starch, and cellulose are both polysaccharides made from glucose monomers; however, only amylose is digestible. What is the biochemical difference that allows amylose to be digested?

Amylose is attached to proteins by glycosylation

Which enzyme binding scenario best describes enzyme specificity and action?

An enzyme binds one substrate or closely related substrates to catalyze only one reaction.

What stimulates beta-oxidation of fatty acids?

An increase in NAD + concentration in the mitochondrial matrix

What is the effect of ph on hemoglobin fiber formationi in sickle cell anemia?

At a lower ph hemoglobin aggregates to form fibers

Which metabolic pathway involves coenzyme A, NAD, and FAD?

Beta oxidation

How do rising blood CO 2 levels promote the deoxygenated conformation of hemoglobin?

CO 2 reacts with H 2O in the blood and decreases pH, which promotes the dome conformation of the heme group.

Which type of bonding or interaction is correctly paired with a chemical or change in environment that will disrupt/break the interaction or bond?

Changes in pH instead disrupt hydrogen bonds and ionic bonds.

Which cellular molecules assist denatured proteins in refolding into a functional form?

Chaperones

Which of the following is required for DNA polymerase to replicate template DNA in PCR?

DNA primers

Which situations would block the synthesis of fatty acids in the liver?

Defect in enzyme required to convert acetyl coa into pyruvate

How does hemoglobin keep blood pH neutral during exercise?

Deoxygenated hemoglobin binds to excess H + .

Which molecule is produced when two amino acids are joined by a peptide bond?

Dipeptide

SH indicates

Disulfide bonds

A patient has received a large dose of ionizing radiation at his place of employment. Which scenario is accurate?

Double-stranded DNA breaks are being repaired by nonhomologous end joining, without the use of a homologous template.

How does the misfolding of protein structure at the teriatary level lead to aggregation seen in neurodegenerative diseases such as alzheimer's ?

Exposed hydrophobic amino acids cause the misfolded proteins to stick together

Which molecule acts as the primary signal for glycogen breakdown?

Glucagon

Which complex polysaccharide acts as an energy-storing molecule in the liver?

Glycogen

Long-distance runners often consume energy gels that are high in carbohydrates during their run. Which pathway is triggered by the intake of carbohydrates during exercise?

Glycolysis

What metabolic pathway is common to both aerobic and anaerobic processes of sugar catabolism?

Glycolysis

What happens to hemoglobin structure as ph increases from 7.2 to 7.4?

Hemoglobin shifts to R state

Identify the factors that favor the oxygenated form of hemoglobin

High pH, low carbon dioxide

Which reaction is involved in the digestion of proteins?

Hydrolysis

What type of reaction breaks peptide bonds apart?

Hydrolysis Reaction

Which force is most influential in determining the tertiary structure of a protein

Hydrophobic effect

How does L-DOPA supplementation for patients with parkinson's disease increase dopamine availability?

Increases available substrate for dopamine production

Immediately following transcription, mRNA must be processed before it is transported to the cytoplasm to undergo translation. Which statement correctly describes mRNA processing?

Introns are spliced out and exons are connected to produce a mature mRNA sequence.

A diabetic patient is suffering from ketoacidosis. Which interaction(s) could be disrupted within the patientʼs hemoglobin due to this condition?

Ionic bonds and hydrogen bonds'. Diabetic ketoacidosis leads to a lower pH than normal. Changes in pH can disrupt both hydrogen bonds and ionic bonds inside of a protein.

Which of the following statements about protein structure and stability is true?

Ionic bonds between the side chains of the charged amino acids stabilize the protein structure. Ionic bonds help stabilize both the tertiary structure of a protein chain and the quaternary structure of a protein with multiple subunits. When a protein is denatured, all levels of structure except for primary are lost.

Which metal ion is bound to the porphyrin ring in hemoglobin?

Iron

Which of the following statements describes the tertiary structure of a protein?

It involves hydrogen bonding between amino acid side- chains'. Secondary structures arise from hydrogen bonding patterns between backbone atoms. The most common secondary structures are alpha-helices and beta sheets.

Which of the following does not occur when a protein is misfolded?

It loses its primary structure'. The primary structure is determined by the peptide bonds between amino acids in the protein, which are strong covalent bonds that are not broken by the protein changing shape or from conditions which cause the protein to misfold and denature

What is the function of DNA polymerase in the process of PCR?

It recognizes the primers and uses the available dNTPs to replicate the template DNA sequence.

How does insulin impact carbohydrate metabolism?

It stimulates the uptake of glucose from the blood by cells in the body.

Which feature of hemoglobin makes it an effective oxygen transport molecule?

Its affinity for oxygen is regulated by pH.

Which cellular condition prompts the cell to perform fermentation rather than the citric acid cycle?

Lack of O2

Which factors favor the deoxygenated form of hemoglobin?

Low ph and high carbon

What is a function of cholesterol?

Maintains membrane fluidity

Which cellular organelle required for the citric acid cycle and electron transport chain is not present in red blood cells?

Mitochondria

Which molecule is replenished by fermentation?

NAD+

Which product of the citric acid cycle is needed to continue aerobic metabolism

NADH

Which type of disease is typically associated with abnormal aggregation of proteins

Neuro Degenerative

the enzyme acetylcholinesterase breaks down the acetylchole in the brain leading to neuron degenerations. Which of the following strategies represents the best way to increase acetylcholine levels?

Non-competative inhibition of acetylcholinesterase.

Which type of inhibition occurs when a particular drug binds to the allosteric site of an enzyme and subsequently changes the enzyme's structure?

Noncompetitive

Which of the following amino acids would you expect to find in the interior of a protein rather than on its exterior?

Nonpolar/ hydrophobic

What is a difference between myoglobin and hemoglobin?

Only one displays cooperatively in O2 binding

What is a temporary modification to protein structure by kinases that alters enzyme function?

Phosphorylation

NH indictaes

Polar/ hydrophilic

Which level of protein structure is established through the dehydration synthesis of peptide bonds?

Primary

How would lipid production in a cell change in order to maintain fluidity of its cell membrane as it adapts to lower temperatures?

Produce lipids with shorter fatty acid chains

An active elderly patient is becoming frequently disoriented, having trouble recalling her daily routine, and becoming aggravated easily. She forgets words and places and has difficulty recognizing her children. Which biochemical event is responsible for this patient's behavior?

Protein aggregation

Pepsin, the enzyme that catalyzes the breaking of peptide bonds, has the highest activity in the acidic environment of the stomach. What process is disrupted after a patient ingests excessive antacid that neutralizes the pH of the stomach?

Protein catabolism

What is the name of large, functional protein structures composed of smaller proteins with multiple subunits?

Quaternary structure

Which type of mammalian DNA damage repair requires the presence of the chromosome that is homologous to the damaged chromosome?

Recombination

A toddler mistakenly swallows a bathroom cleaning solution, containing a strong reducing agent. Which interaction is most likely to be disrupted within a glycoprotein in the lining of the toddlerʼs esophagus?

Reducing agents disrupt disulfide bonds.

Which type of DNA damage is corrected by mismatch pair?

Replication error

What is the order of processes that occur during base excision repair of a strand of mammalian DNA after damage has been identified?

Section of homologous chromosome is aligned with damaged section, correct oligonucleotide is synthesized, DNA backbone is ligated

Proteases are a class of enzymes that hydrolyze protein strands into smaller units. A particular protease, located in the stomach, demonstrates activity at a pH = 1. What is the impact on the protease activity if the pH is increased to 7.4?

Significantly decrease

Which change will likely increase the activity of an enzyme currently at optimal conditions?

Significantly increasing substrate concentration

Hydrophobic interactions are disrupted by changes in

Temperature/ heating

Which structural level is impacted by denaturing a protein containing a single polypeptide?

Tertiary

What is occurring in surrounding tissues as the amount of hemoglobin saturated with oxygen increases?

The concentration of hydrogen ions decreases.

What occurs immediately after the appropriate molecule enters the active site of an enzyme?

The enzyme binds the molecule to form an enzyme-molecule complex.

What happens to hemoglobin structure as ph decreases from 7.4 to 7.2?

The heme groups become dome shaped

In what condition does hemoglobin bind to oxygen most readily?

The hemoglobin is already bound to one oxygen molecule

Which of the following statements about the different levels of protein structure is true?

The interactions between the side chains of the amino acids make up the tertiary level structure of a protein'. Two or more polypeptides each with their own tertiary structures come together to form a single larger quaternary structure of a protein.

What occurs during RNA processing to form a mature mRNA?

The introns are removed from the mRNA

Xeroderma pigmentosum (XP) is a recessive genetic disease that occurs when one or more of the genes that perform nucleotide excision repair are nonfunctional. Why do XP patients have a much higher incidence of skin cancer than the general population?

The mutation rate of all other genes is higher due to failure to repair.

How do enzymes eliminate the need for high temperatures to complete a reaction?

The need for high temperature is eliminated by lowering the activation energy needed for the reaction.

What difference in the regions of the SIRT1 and SIRT2 genes in people addicted to cocaine increases their expression?

The nucleosomes become more widely spaced.

What causes the symptoms of noninsulin-dependent (Type 2) diabetes?

There are not enough GluT4 transporters on plasma membranes.

What is an accurate description of the proton gradient that is formed during aerobic metabolism?

There is a higher H + concentration in the intermembrane space than in the matrix.

How do the rates of enzyme-catalyzed reactions compare to those of corresponding uncatalyzed reactions?

They are 10 6 to 10 12 times faster.

What is a characteristic of protein denaturation?

They are irreversibly functional

Which of the following interactions can occur between two positively charged amino acids?

Two positively charged amino acids would repel each other. Only opposite charges attract. Ionic bonds occur between two oppositely charged amino acids.

Which vitamin is not absorbed by phospholipid micelles?

Vitamin C

which type of molecule can be used in gluconeogenesis

amino acid

Hydrogen bonds are disrupted by

changes in pH and by increasing the concentration of salts in the protein's environment.

An athlete is preparing for a race and consumes a carbohydrate heavy meals days before. which pathway is triggered by an excess intake of carbs?

gluconeogenesis

Glucose and glycogen stores are depleted during long-distance running. Which pathway is responsible for providing energy for glucose-dependent cells, such as brain cells, during extended periods of exercise

gluconeogenesis

Which process is an example of an anabolic pathway

glycogenesis

Which of the following forces can lead to aggregation as a result of protein misfolding?

hydrophobic interactions'. Misfolded proteins can have sections of hydrophobic amino acid residues exposed to water. This can lead to misfolded proteins to aggregate in order to form favorable hydrophobic interactions between nonpolar amino acids in adjacent protein chains and to keep these hydrophobic residues away from water.

Which molecule in the blood can provide evidence of a heart attack?

myoglobin

Which of the following interactions involve a covalent bond?

peptide bond and disulfide bond'. A covalent bond is a bond between two atoms involving the electrons being shared between them.

Positive charged amino acids will be attracted

to the negatively charged amino acids.

What would produce the least amount of ATP in a person with a medium chain acyl-CoA dehydrogenase deficiency/ MCADD

triglycerides with three 10 carbon fatty acid chains