Principles of Biochemistry Final Exam Review

Which of the following would not be a major focus of biochemists?

Examining how volcanic eruptions affect weather patterns.

A molecule with the formula C10H18O is most likely to be an

lipid

The most abundant functional group in glucose is a

hydroxyl group

To separate a polynucleotide into individual nucleotides, what type of bond must be broken?

phosphodiester bond

which type of polymer is commonly used for energy storage?

Carbohydrates

when a chemical reaction occurs, you can be sure that the reacting system’s

free energy decreases

what is the free energy change for a reaction at 25C when H=-15,000 J mol -1 and S=-75 J K mol-1

7.4 kJ mol-1

A thermodynamically unfavorable chemical reaction can occur in a cell because

the unfavorable reaction can be coupled to a favorable reaction

which process was necessary for prebiotic evolution?

replication

The three domains of life are

archaea, bacteria, and eukarya

How do eukaryotic and prokaryotic cells differ?

Only eukaryotic cells have a nucleus

The human microbiota

can be disrupted by drugs

Which theme in biochemistry explains why children typically look like their biological parents?

Biological information is transmitted from generation to generation.

Some enzymes (proteins) in eukaryotes bind to substrates by a lock-and-key mechanism. What theme in biochemistry does this support?

Living organisms are composed of macromolecules

which of the following correctly identifies the progression from individual molecules to a functioning multi-cellular organism?

molecules, organelle, cell, organ, organism

The non-protein part of a protein is called the

prosthetic group.

which of the following amino acids contains an amine side chain?

Arg

cholesterol is a _____ that dissolves in a ____ solvent

lipid; nonpolar

In sickle cell anemia, a mutation occurs and glutamic acid is replaced by valine. What effect would you expect to observe?

Since glutamic acid is a polar and valine is nonpolar, the protein would now change its orientation and move towards the exterior in aqueous solution.

For an exothermic change, H is

negative

If H is positive, the reaction is

endothermic.

Which one of the following equations is correct?

H=E+PV

Enthalpy change is the heat of reaction at

constant pressure.

Which statement best explains the evidence for the endosymbiotic theory?

Chloroplasts contain DNA

What makes scientists believe that eukaryotes descended from a single ancestor?

Presence of membrane-bound nuclei in all eukaryotes

How did early eukaryotes differ from eukaryotes today?

they were mostly unicellular

which statement about mitochondria formed by endosymbiosis of prokaryotes is true?

Many genes were transferred to the host nucleus

A buffer solution has the following characteristic:

pH is unaffected upon dilution.

A patient reports to the emergency room expelling gastric juices. What condition would you suspect the patient to have?

Metabolic alkalosis

which of the following can deprotonate water?

hydride ion

which statement best explains why buffers are best made when the desired pH is within one unit of the corresponding weak acid’s pK?

Solutions typically resist changes in pH up to the point where the molar concentrations of weak acid and conjugate base are within a factor of 10.

10. mL of a 0.28 M solution of acetic acid, Ka =1.8×10-5, is added to a 20. mL of 0.18 M solution of sodium acetate. What is the pH of the solution?

4.84

Carboxylic acids are weak acids, typically having pKa values in the range of 3-5.

True

the weaker acid and weaker base are ____ than the stronger acid and stronger base.

more stable

Severe dehydration will most likely lead to a decrease in the ____.

Blood pH

Carboxylic acids are weak acids, typically having pKa values in the range 1-2.

False

A nucleoside consists of

a base and a sugar

Choose the false statement about DNA

The double helix twists in a left-handed manner.

A strand of RNA can form base pairs…

with a strand of DNA or RNA

In order for two polynucleotide strands to anneal,

the strands must be complementary

Copying a segment of DNA to make a segment of RNA is called

transcription

A messenger RNA with AGCUUGCAG codes for a protein with the sequence

Ser-Leu-Gln

A monogenic disease

results from a defect in one gene

A single-nucleotide polymorphism

may indicate increased risk for a disease

Horizontal gene transfer

occurs between different species.

Nucleic acids are polymers of

nucleotides

The first cells probably contained RNA, since this molecule

can make copies of itself.

Hydrogen bonds typically involve

N-H and O-H groups

Which carbons are involved with the phosphodiester bond in the CA (ribo)dinucleotide?

C3 of the ribose sugar of the cytosine nucleotide and C5 of the ribose sugar of the adenine nucleotide.

Chargaff’s rules hold true for RNA

False

A peptide built from three amino acids must have

three side chains

In an a helix, each carbonyl group

is a hydrogen bond acceptor

A B sheet is a type of regular secondary structure because

each residue has the same backbone conformation

Which type of interaction in a protein’s tertiary structure is covalent?

disulfide bond

What happens soonest during the protein folding process?

Hydrophobic groups move to the protein interior

which statement about protein structure is most accurate?

Metamorphic proteins can perform two different functions

Intrinsically disordered proteins

can adopt a stable conformation after binding another molecule

A protein with quaternary structure

contains more than one subunit

A polypeptide that does not assume its proper three-dimensional structure

-may be degraded

-may re-fold

-may accumulate

(all of the above)

The aggregation of a misfolded protein may lead to

a neurodegenerative disease

Without a heme prosthetic group;

hemoglobin would not bind oxygen

Myoglobin, a globin, and B globin have similar structure because

they evolved from a common ancestor

Respiring tissues release CO2, which leads to

a shift to the T state of hemoglobin

Mutations in the genes for a hemoglobin a or B chain

-may cause anemia

-may increase O2 binding

-may decrease O2 binding

(all of the above)

Which type of structural protein is exclusively extracellular?

collagen

The changes in cell shape that allow crawling are mainly result of

actin filament assembly and disassembly

The motor protein myosin has

two heads attached to a rigid neck lever

The weak forces that allow molecules to interact with each other include all except

covalent bonds

Most globular proteins

undergo small conformational changes

An enzyme’s specificity refers to

what substrates the enzyme acts on

Enzymes are classified according to

the type of reaction they catalyze

An enzyme accelerates a chemical reaction by

making it easier for reactants to reach the transition state.

A protonated side chain in an enzyme’s active site

can donate a proton during catalysis

An enzyme that carries out metal ion catalysis

includes a cofactor

The oxyanion hole in chymotrypsin

helps stabilize the reaction’s transition state

The plasma concentrations of the coagulation factors correlate with

the order in which the enzymes become active

Two charged groups can reversibly interact by

forming an ionic bond

What type of transporter is responsible for moving water across membranes?

aquaporin

Which of the following statements regarding membrane transporters is true?

Amphotericin is able to assemble inside a membrane in such a manner to form a channel through which K+ and Na+ flow, thus disrupting the ion gradient.

Which amino acid in the aquaporin channel hydrogen bonds with water to prevent the movement of protons?

Asn

Which of the following is true regarding the glucose transporter?

Binding of glucose causes a conformational change so that the transporter is never open on both sides of the membrane

The Na,K-ATPase is a(n) ____ that moves Na+ from ____ and K+ from ____.

antiporter; inside to out; outside to in

Hydrolysis of ATP by the Na,K-ATPase moves ____ while hydrolysis of the phosphate moves _____.

3 Na+; 2 K+

The P-glycoprotein is an example of a(n) ____ which has been linked to drug resistance in the treatment of ___.

ABC transporter; cancer

Transport of glucose from the intestine into the intestinal cells is accomplished by a(n) ____. This is an example of ___.

symporter; secondary active transport

Which of the following occurs during the fusion of a synaptic vesicle and cell membrane?

Selective removal of acyl chains from membrane phospholipids allows the bilayer to bow outward.

The GLUT proteins have little structural resemblance to other transport proteins despite having a similar mechanism of transport.

False

The GLUT transporters have a 12-stranded B-barrel structure that spans the membrane of the cell.

False

Pinocytosis is a specific type of exocytosis where small amounts of intracellular material are sequestered in a vesicle followed by membrane fusion and transport of the material to the outside of the cell

False

Integrins and aquaporins are examples of ___.

integral membrane proteins

A pore that simultaneously transports two different molecules in different directions is called __.

an antiport

A type of lipid that commonly forms a waterproof barrier and is composed of a fatty acid and a fatty alcohol is called a ___.

wax

Which of the following explains why free fatty acids do not form bilayers?

The width of the polar head is greater than the nonpolar tail.

As temperatures grow colder with the onset of winter, animals will adapt by changing the fatty acid composition of cell membranes. What characteristics of fatty acids will be seen?

shorter chains with greater unsaturation

A membrane raft is a(n) ___ in the lipid bilayer of a cell membrane.

region of high cholesterol and sphingolipid content

Which of the following is true regarding membrane asymmetry?

none of the above

Which of the following statements describes integral membrane proteins?

The amino acids that contact the core of the membrane are hydrophobic

If a transmembrane domain of protein contains B-sheet structure, the overall structure of the transmembrane portion is likely a ___.

B-barrel

If polar amino acids are found in a membrane spanning a-helical region, they are most likely __.

hydrogen-bonded to other polar amino acids to prevent interaction with the membrane lipids

Which of the following is a characteristic of integral membrane proteins?

Most of their movement is by lateral diffusion