Biochemistry 3

What is a coenzyme?

Contains only protein

A non-protein compound that assists enzymes in catalyzing reactions

A molecule that inhibits enzyme activity

A specialized protein that activates metabolic pathways

To transport a polar compound across the biological membrane from an area of low to an area of high concentration

A) The compound partitions into the lipid bilayer because of its polar properties.

B) Involves the compound moving down its concentration gradient facilitated by transport proteins

C) Requires the input of energy in the form of ATP or proton motive force

D) Involves only uniporters

E) None of the above

=multiplechoice Which of the following carbohydrates will convert cupric oxide to cuprous oxide?

=multiplechoice Transport of Na+ ions across the biological membrane involves

A) Only energy dependent uniporters

B) Both active and passive facilitated transport

C) Only energy dependent symporters

D) Passive diffusion

E) A symporter which also transports K+

=multiplechoice In glycolysis, energy is extracted from glucose in the form of

A) NADH + H+ and ATP generated by substrate level phosphorylation

B) ATP generated by oxidative phosphorylation

C) FADH2 and ATP generated by substrate level phosphorylation

D) Proton motive force

E) NADH + H+ and ATP generated by oxidative phosphorylation

=multiplechoice helix and -sheet are examples of

A) Secondary structural elements of proteins

B) Mechanisms for binding substrate to an enzyme

C) Protein folds

D) Mechanisms to increase the VMAX of the enzyme

E) Secondary structure elements of DNA

=multiplechoice Insulin

A) Is a peptide hormone, synthesized in the pancreas, which increases blood glucose levels

B) Is a peptide hormone, synthesized in the liver, which increases blood glucose levels

C) Is a peptide hormone, synthesized in the pancreas, which decreases blood glucose levels

D) Is a peptide hormone, synthesized in the liver, which decreases blood glucose levels

E) Is a steroid hormone, synthesized in the pancreas, which increases blood glucose levels

Glycolysis and the citric acid cycle are linked in aerobic respiration. The key step in linking these processes is

A) The harvesting of electrons by glycolysis for use in the citric acid cycle

B) The conversion of the 6 carbon sugar Fructose-1,6-bisphosphate to two 3 carbon sugars

C) The transfer of electrons onto oxygen

D) The conversion of pyruvate to acetyl CoA during transportation through the mitochondrial membranes

E) All of the above

=multiplechoice The citric acid cycle generates

A) FADH2, NADH + H+ and ADP

B) ATP generated by oxidative phosphorylation

C) FADH2, NADH + H+ and ATP generated by substrate level phosphorylation

D) Proton motive force

E) NADH + H+ and ATP generated by oxidative phosphorylation

=multiplechoice The formation of a blot clot requires

A) Cleavage of fibrin, and the deposition of insoluble fibrinogen through electrostatic interactions

B) Tissue plasminogen activator generation of fibrin cross-linking

C) Cleavage of fibrinogen by thrombin, and deposition of insoluble fibrin

D) A cascade of events leading to the formation of the membrane attack complex

E) All of the above

=multiplechoice Estrogen binds to

A) Membrane receptors and activates G protein

B) A ligand gated ion channel

C) The insulin receptor and causes dimerization

D) A receptor located in the nucleus

E) Phospholipase C and increases synthesis of diacylglyceride

=multiplechoice Which two cellular processes are simultaneously regulated by adrenalin?

A) Amino acid uptake and protein synthesis

B) Glycogen breakdown and glycogen synthesis

C) Fat synthesis and glucose breakdown

D) Gluconeogenesis and fat breakdown

E) Oxidation and reduction reactions

=multiplechoice G proteins are

A) Membrane receptors

B) A ligand-gated ion channel

C) Receptor-associated GTP-binding proteins

D) A receptor located in the nucleus

E) A structural component of the basal lamina

=multiplechoice The isoelectric point (pI) of a protein is the pH

A) At which the protein structure is optimal for its particular function

B) At which the protein is negatively charged and dissolves in alkali

C) At which the protein has a net zero charge

D) At which the protein is positively charged and dissolves in acid

E) At which all enzyme activity is prevented

=multiplechoice In oxidative phosphorylation

A) Protons (H+) are pumped out of the mitochondrial matrix by complex V

B) Protons (H+) are pumped out of the mitochondrial matrix by complexes I, III and IV

C) Electrons (e-) are pumped out of the mitochondrial matrix by complexes I, III and IV

D) ATP is synthesized by substrate level phosphorylation

E) NADH + H+ and FADH2 are generated.

=multiplechoice Cellulose is

A) A component of the basement membrane, to which cells attach

B) A polymer of glucose with α 1-6 glycosidic linkages

C) A polymer of glucose with α 1-4 glycosidic linkages

D) A polymer of glucose and fructose

E) A polymer of glucose with β 1-4 glycosidic linkages

=multiplechoice In oxidative phosphorylation

A) Pyruvate is converted to acetyl Co A by the addition of electrons

B) Electrons will flow from a compound with a positive standard reduction potential (E’o) to one with a negative E’o.

C) Electrons are transferred from NADH through membrane complexes I, III and IV to ADP generating ATP

D) Electrons are pumped into the mitochondrial matrix from the intermembrane space

E) Electrons are transferred from NADH through membrane complexes I, III and IV to O2 generating H2O

=multiplechoice 18. Chargaff’s rule implies that

A) C hydrogen bonds to G, and A hydrogen bonds to T

B) The ribose sugars are different in DNA and RNA

C) Any purine hydrogen bonds to any pyrimidine

D) The lipid tail of triglycerides form micells

E) Uracil is used to fulfil all hydrogen bond potentials

=multiplechoice Collagen is

A) Composed of entirely α-helical protein structure

B) Is a triple helical protein structure

C) A type of phospholipid

D) A membrane bound hormone receptor

E) A double helical protein structure

=multiplechoice A simple enzyme

A) Has only one substrate

B) Catalyses only lyase reactions

C) Contains only protein

D) Has a heme prosthetic group

E) Does not lower the energy of activation

A Complex enzymes (2 correct)

Prosthetic group – covalently or tightly bound group

Require metal atom for activity

Additional small organic moeity

Catalyses only protase reactions

Biochemistry 3

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