Biochem FInal

1. Which of the following factors influence enzyme activity?
a. Concentration of substrate
b. temperature
c. all of the above
d. concentration of enzyme

Beta oxidation in lipid pathways involves
a. activating fatty acids and breaking them down into 2 carbon segments
b. formation of saturated and unsaturated fatty acid molecules
c. removal of amine groups from fatty acids
d. conversion of fatty acids into amino acids

The reactions of anaerobic respiration occur in the
a. all of these
b. mitochondria
c. cytoplasm
d. nucleus

If a DNA strand has the organic base sequence T, T, A, C, G, A, the corresponding base sequence of a messenger RNA molecule would be
a. A, A, T, G, C, T
b. A, A, U, G, C, U
c. T, T, A, C, G, A
d. U, U, T, G, C, T

How many ATP are produced in the krebs cycle proper (in the matrix of the mitochondria)?
a. 36
b. 30
c. 12
d. none

A molecule that is common to carbohydrate and lipid metabolic pathways and serves to connect these two pathways metabolically is
a. glucose
b. pyruvic acid
c. acetyl coenzyme A
d. glycogen

The common starting point for the Embden-Meyerhoff pathway is
a. pyruvic acid
b. glucose 1-phosphate
c. glucose
d. glucose 6-phosphate

In RNA, uracil replaces ___________.
a. guanine
b. cytosine
c. adenine
d. thymine

Which type of enzyme poison would most likely be the most toxic?
a. irreversible inhibitor
b. noncompetitive inhibitor
c. competitive inhibitor

The reduction of pyruvic acid to lactic acid in Step 11a of the Embden-Meyerhoff pathway is essential because it regenerates the ___________ that is needed in Step 6. If this coenzyme were not replenished, the cell’s supply could rapidly be depleted, the pathway would cease, and glyceraldehydes 3-phosphate would accumulate in the cell.
a. FADH
b. ATP
c. NAD+
d. PEP

When the DNA replicates during interphase, the resulting DNA molecules are correctly described by which of the following?
a. Each new DNA molecule contains one old strand and one new strand.
b. One DNA molecule contains two old strands, the other has two new strands.
c. Entirely new strands of DNA are made.
d. Each DNA molecule contains some old DNA and some new in each strand.

The conversion of succinyl-CoA to succinic acid in the Krebs cycle is accompanied by the production of

Most biochemical processes occur in several steps, each catalyzed by a different
a. ion
b. metal
c. substrate
d. enzyme

The transfer of genetic information from the nucleus to the cytoplasm is a function of
a. ribosomal RNA
b. transfer RNA
c. DNA molecules
d. messenger RNA

Urea results from the metabolism of
a. fatty acids
b. monosaccharides
c. amino acids
d. glycerol

Nucleotides are bound together into nucleic acids by ester linkages between a phosphate group and the third and fifth carbons on either a ribose or deoxyribose sugar group. These linkages are called ___________.
a. 3’, 5’ phosphoester linkages
b. 3’, 5’ phosphodiester linkages
c. 5’, 3’ phosphoester linkages
d. ester bonds

A ______________ is any compound that bears a close structural resemblance to a particular substrate and competes with that substrate for binding at the same active site on the enzyme.
a. noncompetitive inhibitor
b. competitive inhibitor
c. terminal inhibitor
d. irreversible inhibitor

One less ATP is consumed in the Ebden-Meyerhoff pathway when the reaction uses glucose 1-phosphate, derived from ____________ as the initial substrate.
a. starch
b. glycogen
c. glucose
d. fats

The conversion of pyruvic acid to acetyl CoA in Step 1 of the Krebs cycle is______.
a. terminal
b. competitive
c. irreversible
d. reversible

Which of these compounds is not a ketone body produced in ketogenesis?
a. acetone
b. pyruvic acid
c. acetoacetic acid
d. B-hydroxybutyric acid

The electron acceptor at the end of the electron transport chain is ___________.
a. pyruvic acid
b. succinic acid
c. oxygen
d. hydrogen

If a strand of a DNA molecule contained the base sequence C, T, A, G, C, the complementary strand would contain the base sequence
a. G, A, T, C, G
b. T, G, C, A, T
c. C, T, A, G, C
d. A, G, C, T, A

When fats are metabolized in the absence of carbohydrates, much of the acetyl CoA produced cannot enter the Krebs Cycle because of a shortage of ___________, which is being used to create glucose via gluconeogenesis.
a. pyruvic acid
b. citric acid
c. oxaloacetic acid
d. fumaric acid

Complete hydrolysis of DNA ultimately gives two purine bases and two pyrimidine bases. The pyrimidine bases are _________ and ___________.
a. guanine and thymine
b. adenine and guanine
c. cytosine and thymine
d. adenine and cytosine

A cofactor is defined as ____________ and examples are _____________.
a. an inorganic molecule needed by some enzymes; vitamine B12 and B6
b. an inorganic molecule needed by some enzymes; cholesterol and calcium
c. a molecule that destabilizes substrates; carbonic acid
d. a necessary part of some enzymes; copper, iron, and zincA cofactor is defined as ____________ and examples are _____________.
a. an inorganic molecule needed by some enzymes; vitamine B12 and B6
b. an inorganic molecule needed by some enzymes; cholesterol and calcium
c. a molecule that destabilizes substrates; carbonic acid
d. a necessary part of some enzymes; copper, iron, and zinc

A mutation is
a. a change in the DNA molecule, which changes the protein that will be formed
b. a lack of replication of DNa before cell division
c. a problem with the way mRNA molecules leave the nucleus
d. a change in the rate of protein synthesis from mRNA

Which of the following substances increases in amount during cellular respiration?
a. oxygen
b. glycogen
c. glucose
d. ATP

In the Embden-Meyerhoff pathway, ATP is consumed in steps _________ and generated in steps ___________.
a. 2 and 4, 6 and 9
b. 1 and 3, 7 and 10
c. 2 and 4, 6 and 10
d. 1 and 4, 6 and 9

The nucleotides are phosphate ___________ of the nucleosides and may be envisioned to result from the ___________ of phosphoric acid with one of the free pentose hydroxyl groups.
a. esters, esterification
b. bases, alkinilization
c. acids, acidification
d. friends, fraterinization

In the DNA double helix, the base pairs serve as the connecting points of the DNA strands. The complementary base pairs are always formed from a __________ and ________, in order to give the proper width.
a. purine and purine
b. acid and base
c. purine and pyrimidine
d. pyrimidine and pyrimidine

The vaso-dilator histamine is produced by the decarboxylation of histidine. Allergic individuals synthesize abnormally high amounts of histidine.

Succinic acid dehydrogenase is the only enzyme of the Krebs Cycle that is located within the inner mitochondrial membrane. This permits electrons to be transferred directly into the electron transport chain when the FADH2 is reoxidized.

All amino acids are used in the synthesis of proteins.

The backbone of nucleic acid is a polyester chain.

Vitamins are substances that cannot be synthesized in sufficient quantities by human cells.

Production of excess ketone bodies will lead to the condition of ketoacidosis.

The Embden-Meyerhoff pathway is called a pathway rather than a cycle because its final product serves as the substrate for its initial reaction.

A metabolic pathway is a particular sequence of enzyme-controlled reactions.

The average indivdual requires about 50-60 grams of protein in the daily diet to provide for the biosynthesis of the various nitrogenous compounds. Amounts of protein in excess of this are stored as muscle.

Transfer RNA serves in protein synthesis by bringing amino acids to the ribosome and positioning them in relation to the codon sequence of the messenger RNA.

Succinic acid dehydrogenase is th only enzyme of the Krebs Cycle not located within the inner mitochondrial membrane.

The amines produced in deamination are excreted by humans as water soluble urea. The excessive use of proteins as an energy source in starvation may lead to a profound dehydration.

Vitamins function as cofactors and minerals function as coenzymes in regulating enzyme activity in a biochemical pathway.

The fatty acids found in triglycerides have an even number of carbons because they are constructed from acetyl groups.

The process of regulating enzyme activity by acting on a site other than the active site is called allosterism.

Increasing the concentration of a substrate would decrease enzyme activity by clogging up the active site on the enzyme.

Transamination is an exchange of functional groups between amino compounds and keto compounds. The amino group is transferred to one of three alpha-keto compounds: pyruvic acid, alpha-ketoglutaric acid, or oxaloacetic acid.

At any given moment the amino acid pool would contain about 600 grams of amino acids.

In DNA, adenine and thymine always bond with two hydrogen bonds, while cytosine and guanine always bond with three hydrogen bonds.

Enzymes are necessary to lower the energy of activation of a chemical reaction so that they might proceed within homeostatic range.

Enzymes are necessary to lower the energy of activation of a chemical reaction so that they might proceed within homeostatic range.

Mammals can convert carbohydrates to lipids, but they cannot convert lipids to carbohydrates because the conversion of pyruvic acid to acetyl CoA is irreversible.

Fibrous proteins are insoluble in water. Globular proteins, the other major class, are soluble in aqueous media.

n DNA, adenine and thymine always bond with three hydrogen bonds, while cytosine and guanine always bond with two hydrogen bonds.

Purine and pyrimidine

Purine or pyrimidine combined with a pentose sugar

Purine or pyrimidine, pentose sugar, and phosphate

RNA and DNA

_e__61. Urea

Uracil

substance that interferes with respiratory enzymes

Ketone Body

Nucleotide

Where does transcription occur in the cell?

What does the Zwitter ion form of an amino acid have to do with its solubility?

Why is it structurally important in the DNA double helix that a purine base always pair with a pyrimidine base?

What is the most significant property of a protein?

Why does the NADH produced in the cytoplasm yield only two ATP?

What is a Zwitter ion? What is the structural formula?

How many ATP (net) are produced in the oxidative pathway during the oxidation of one glucose molecule?

What are the three differences between DNA and RNA?

What five types of side chain interactions give structure to tertiary and quaternary proteins?

Why would a rise in serum levels of transaminases indicate cellular pathology?

What two distinct chemical processes occur at the first functional carbon of glyceraldehydes 3-phosphate in the sixth step of the Embden-Meyeroff pathway?

What is the primary functional difference between a secondary and tertiary protein?

What are three sources of amino acids for the amino acid pool?

What is the mechanism for restoring NADH to NAD+ in the oxidative pathway called?

What are the products of cleavage when fructose 1,6 diphosphate is slit into two three carbon structures?

Why are mitochondria essential for efficient utilization of all food sources?

Which steps in the Krebs cycle produce an NADH?

Which type of enzyme specificity is least common?

What pathology most commonly accompanies starvation and why?

What is encoded by the genetic code?

The modification of a protein molecule so that it no longer folds or functions properly is called _________________.

Which protein form is easiest to digest?

What is the name of the enzyme complex involved in the replication of DNA?

What is the name of the enzyme complex that catalyzes Step 1 of the Kreb cycle?

Which steps in the kreb cycle produce a thioester?

Why are certain amino acids considered to be essential?

Name three reagents or conditions that will cause the denaturation of proteins.

What is the common metabolic pathway for all food sources?

What are the four classifications of amino acids, according to the nature of their side chains?

Why does the Embden-Meyerhoff pathway yield twice as much energy as it consumes?

Amines can be produced by the ____________ of amino acids.

What is the name of the enzyme that catalyzes the second step of the Krebs cycle and how does it function as “the fat switch”?

Name three B vitamins that serve as essential co-enzymes in the enzyme complex that catalyzes Step 1 of the Kreb cycle?

Draw the Zwitter ion structure of an amino acid in an alkaline solution.

What purine always bonds to thymine, explain why.

Why does cellular respiration produce an acid state in the cell?

Where does substrate level phosphorylation occur in the cell?

What would be the difference between a nucleoside and a nucleotide?

Why do we use fat as an energy storage form, rather than using a polymer of glucose exclusively?

What four chemical transformations occur at Steps 1 and 6 of the kreb cycle?

What are the products of one turn of the fatty acid spiral?

Where does translation occur in the cell?