BIOCHEM FINAL

How many double bonds are present in palmitic acid?

0

When substrate concentration is equal to KM, the rate of catalysis is ____ Vmax of the enzyme reaction.

0.50

What is the [H+] concentration in a water sample that has a pH of 8?

10^-8

How does a nucleotide differ from a nucleoside?

A nucleotide is a nucleoside with a phosphate ester linked to the sugar.

Which of the following is true about membranes?

All of the above; are lipid bilayers, electrically polarized, have hydrophobic and hydrophilic properties

Examples of second messengers include ____.

All of the above; cAMP, cGMP, calcium ions, & inositol 1,4,5-triphosphate

Which of the following is a reason why ATP hydrolysis releases a high free energy?

All of the above; resonance stabilization, solvation effects, & electrostatic repulsion

What term describes molecules that have both hydrophilic and hydrophobic moieties?

Amphipathic

What type of membrane transporter moves two species in opposite directions across a membrane?

Antiporter

What term describes an enzyme without its required cofactor?

Apoenzyme

In the peptide Met-Phe-Ala-Gly-Tyr-Arg, which amino acid is at the C-terminus?

Arginine

Which of the following is among the most abundant organic molecules in the biosphere?

Cellulose

What type of organisms obtains its energy by oxidizing inorganic molecules & using CO2?

Chemoautotrophs

The biological role of restriction enzymes in bacteria is ___.

Cleave foreign DNA

Which two amino acids contain a sulfur atom?

Cysteine & methionine

What term describes stereoisomers that are mirror images of each other?

Enantiomers

Two monosaccharides that differ in stereochemistry at only a single asymmetric carbon are called ____.

Epimers

A pyranose ring is a five-membered ring formed from a monosaccharide

FALSE

Arginine kinase contains a catalytic triad in its active site.

FALSE

Beriberi is caused by the lack of cobalamin in the human diet

FALSE

Chitin is a homopolymer of N-acetylgalactosamine

FALSE

D-Amino acids are most often found in proteins

FALSE

For a spontaneous reaction to occur, the ΔG must be positive.

FALSE

Ion exchange resins are used to separate proteins according to their molecular weight

FALSE

Lysozyme is an example of a serine protease

FALSE

Myoglobin and hemoglobin have the same number of subunits

FALSE

Peroxisomes are present in animal cells but not in plant cells

FALSE

Structurally, the protein collagen exists as a double helix

FALSE

Sucrose is composed of two molecules of glucose linked together by a glycosidic bond

FALSE

The DNA backbone is made from repeating glycerol phosphate residues

FALSE

The activity of the enzyme papain depends on the ionizable residues cysteine and lysine.

FALSE

Tryptophan synthase which shuttles its reactant between its 3 active sites is an example of metabolite channeling

FALSE

With a few exceptions, hydrophobic interactions are stronger than covalent bonds

FALSE

What regulatory mechanisms relies on inhibition of the first step of the pathway by the final product of the pathway?

Feedback inhibition

What regulatory mechanism relies on a metabolite produced early in a pathway that activates an enzyme which catalyzes a reaction further down the pathway?

Feedforward activation

A pattern of DNA fragments can serve as a ___ of a particular DNA molecule.

Fingerprint

Which of the following DNA sequences contains a palindromic inverted repeat such as those recognized by restriction enzymes? (only one strand is shown)

GCATATGC

Which form of the guanyl nucleotide is bound to a G protein in its unactivated state?

GDP

Which type of protein purification relies on protein separation based on its molecular weight?

Gel filtration

In collagen, the amino acid ___ appears at every third residue.

Glycine

Which of the following is the storage form of glucose in animals?

Glycogen

What membrane components contain carbohydrates?

Glycolipids

What type of reaction is catalyzed by proteases?

Hydrolysis

What complex is observed between cholesterol and membrane phospholipids?

Lipid raft

Which of the following pairs of amino acids is positively charges at a neutral pH?

Lysine and arginine

Which of the following techniques could be used with a mass spectrometer to determine mass to charge ratio of a molecule?

MALDI-TOF

Structurally, myoglobin exists as a _____.

Monomer

Which of the following coenzymes is derived from nicotinic acid?

NAD+

The scientist that proposed the double helical structure of DNA were ____.

None of the above

Removal of protein phosphates is catalyzed by protein ___.

Phosphatase

What level of protein structure is indicated by its amino acid sequence?

Primary

A covalently bound cofactor for an enzyme is often called a(n) ____.

Prosthetic group

Which of the following enzymes uses biotin as a coenzyme?

Pyruvate decarboxylase

What level of protein structure is only observed in proteins containing multiple subunits?

Quaternary

What type of plot allows one to investigate the likely phi and psi angles if the peptide backbone?

Ramachandran

What level of protein structure is composed of α helices, β sheets, and turns?

Secondary

Which of the following is not considered a chaotrope?

Sodium phosphate

The less active conformational form of an allosteric enzyme is called the ____.

T-state

A competitive inhibitor often has a structure similar to the substrate and often reversibly binds to the active site of the enzyme but can be displaced by substrate.

TRUE

A nucleophile an electron-rich chemical such as water

TRUE

Aggrecan is a major cartilage proteoglycan

TRUE

An example of an enzyme that is activated by a substrate-induced conformational change is hexokinase

TRUE

Antibodies contain heavy and light chains structurally

TRUE

Compounds that resemble the transition state of a catalyzed reaction and inhibit enzyme activity are called transition state analogs.

TRUE

Cytochromes are heme-containing protein coenzymes

TRUE

Glycine is not a chiral amino acid

TRUE

Hemoglobin is an allosteric protein

TRUE

In phosphoglycerides, the fatty acids are linked to the glycerol backbone by ester linkages.

TRUE

Lactose is a disaccharide composed of galactose and glucose joined by a β-1,4 glycosidic bond

TRUE

Lysozyme is present in human tears and saliva

TRUE

Pauling and Corey proposed the α-helix structure of protein

TRUE

Proline is an imino acid

TRUE

The Edman degradation is a procedure used to sequence a polypeptide chain

TRUE

The catalytic mechanism of triose phosphate isomerase involves having a histidine residue at its active site

TRUE

The endoplasmic reticulum is coated with ribosomes actively synthesizing proteins

TRUE

The isoelectric point of a protein is reached when the net charge of a protein is zero.

TRUE

The mobility of proteins in SDS-PAGE is inversely proportional to the logarithm of their molecular weight

TRUE

The nucleoside that is composed of a D-ribose linked to a cytosine base is called cytidine.

TRUE

The parallel β-sheet structure occurs when the two strands are oriented in the same directions (NC).

TRUE

The product of superoxide dismutase is hydrogen peroxide

TRUE

The sequential model of allosteric regulation allows for both R and T subunit conformations to exist in the same multimeric protein.

TRUE

The vitamin pantothenate is required for the synthesis of coenzyme A

TRUE

Ubiquinone is also called coenzyme Q

TRUE

X-ray crystallography is used to determine the three-dimensional structure of a protein

TRUE

The three-dimensional structure of a protein is called its _____ structure.

Tertiary

Structurally, human hemoglobin exists as a ____?

Tetramer

What conclusion can be drawn concerning an inhibitor if the Vmax is the same in the presence and absence of the inhibitor?

The inhibitor binds to the same active site as the substrate

The kcat is often referred to as the ___.

Turnover number

In this type of inhibition, the inhibitor can only bind to the ES complex to form an ESI complex.

Uncompetive

The degree of membrane fluidity in bacteria depends mainly on the percentage of ___.

Unsaturated fatty acids

London dispersion forces are another name for _____.

Van der Waals forces

Scurvy is associated with which of the following vitamin deficiencies?

Vitamin C

Which of the following vitamins is deficient in children exhibiting rickets?

Vitamin D

Warfarin is a competitive inhibitor of which of the following enzymes?

Vitamin K reductase

Which of the following types of DNA structurally is a left-handed helix?

Z-DNA

What metal ion is required by carbonic anhydrase for activity?

Zn2+

A term that describes a molecule that contains both positive and negative charges but overall has a neutral charge is a(n) ____.

Zwitterion

What term describes enzymes that are activated by proteolytic cleavage?

Zymogens

Adenylyl cyclase reacts with ATP to produce ____.

cyclic AMP

The term ____ is used to indicate entropy.

ΔS