Quiz 2

Why are free ionic bonds of little importance and relatively unlikely to form in living organisms? 1. Cells are composed mostly of water, which interferes with ionic bonds between free ions. 2. Cells are largely hydrophobic. 3. They are crystals. A. 1 B. 2 C. 3 D. 1 and 2 E. 2 and 3

A. 1

All of the following are parts of a nucleotide EXCEPT: A. a six-carbon sugar. B. a nitrogenous base. C. a five-carbon sugar. D. a phosphate group.

A. a six-carbon sugar.

A proteome is: A. an inventory of all of the proteins in a tissue, cell, or cellular organelle. B. all of the mRNA in a cell. C. the cell's rDNA. D. another name for a genome.

A. an inventory of all of the proteins in a tissue, cell, or cellular organelle.

Which of the following carbohydrates are NOT polysaccharides? A. glucose B. glycogen C. starch D. cellulose E. They are all polysaccharides.

A. glucose

An electronegative atom: A. has a great attractive force for electrons. B. repels electrons. C. repels neutrons. D. has a great attractive force for protons.

A. has a great attractive force for electrons.

The chloride ion has an extra electron relative to the number of protons in its nucleus. Thus, chloride: A. has a negative charge and can bind a cation. B. has lost an electron. C. can bind an anion. D. has a negative charge and is unreactive.

A. has a negative charge and can bind a cation.

The primary structure of a polypeptide is: A. the specific linear sequence of amino acids that constitutes the polypeptide chain. B. the DNA sequence that encodes the protein. C. the three-dimensional structure of the protein. D. the nucleotide sequence of the tryptophan tRNA

A. the specific linear sequence of amino acids that constitutes the polypeptide chain.

The element oxygen (O) has six electrons in its outermost shell. How many covalent bonds will O readily form? A. one B. two C. three D. none

B. two

Which of the following is NOT found in DNA? A. adenine B. uracil C. cytosine D. thymine

B. uracil

What bond is responsible for joining glucose monomers to form the polymer cellulose? A. α (1—>4) glycosidic linkages B. β (1—>4) glycosidic linkages C. α (1—>6) glycosidic linkages D. β (1—>6) glycosidic linkages

B. β (1—>4) glycosidic linkages

Superoxide dismutase (SOD) catalyzes destruction of the superoxide radical, forming which product(s)? A. CO2 and H2O B. Urea C. H2O2 and O2 D. RNA

C. H2O2 and O2

A molecule that is capable of releasing or donating a hydrogen ion is termed a(n) _______. A. pain B. anachronism C. acid D. base E. hydrion

C. acid

What kind of bond results from an equal sharing of electrons? A. ionic bond B. polar covalent bond C. nonpolar covalent bond D. H bond

C. nonpolar covalent bond

Observe the following reaction: HCO3- + H+ ↔ H2CO3 The reaction shown above is carried out in the blood to maintain: A. high pH. B. excess of H+ ions. C. normal pH. D. low pH.

C. normal pH.

What kind of bond results from an unequal sharing of electrons? A. van der Waals forces B. ionic bond C. polar covalent bond D. nonpolar covalent bond E. H bond

C. polar covalent bond

The infectious agent for Creutzfeld-Jakob disease is a _________. A. bacterium B. virus C. protein D. fungus

C. protein

In addition to functioning as stores of chemical energy, carbohydrates: A. are important in cellular metabolism. B. can serve as strong building materials for biological construction. C. can be highly water soluble. D. All of the above answers are correct. E. Only answers B and C are correct

D. All of the above answers are correct.

Molecular chaperones __________________. A. assist folding of a polypeptide chain. B. contribute to the heat-shock response C. assist in the assembly of multi-subunit proteins D. All of the above are correct. E. Only A and C are correct.

D. All of the above are correct.

Which of the following statements about hydrogen bonds is true? A. They can occur between most polar molecules. B. They are weak attractive interactions. C. They can be found between the two strands of a DNA molecule. D. All of the above statements are correct. E. Only A and B are correct.

D. All of the above statements are correct.

Some of the functions of proteins include: A. regulation. B. antibodies. C. growth factors. D. All of these answers are correct. E. Only A and C are correct.

D. All of these answers are correct.

Amino acids: A. can form peptide bonds. B.are composed of a central carbon surrounded by an amino group, a carboxyl group, a hydrogen atom and a variable side chain. C. can have side chains that are polar, nonpolar, or with unique properties. D. All of these statements are true. E. Only A and C are correct.

D. All of these statements are true.

Polar molecules of biological importance may often: A. contain one or more electronegative atoms. B. contain one or more electropositive atoms. C. possess strongly polarized bonds. D. Both answers A and C above are correct.

D. Both answers A and C above are correct.

Which of the following structures of proteins is composed of two or more polypeptide chains? A. Primary B. Secondary C. Tertiary D. Quaternary E. None of the above apply.

D. Quaternary

Amphoteric molecules: A. are branched, with at least two branch points B. have two different types of bonds C. have one region that is positively charged and one region that is negatively charged D. able to act as an acid and a base E. have one region that is polar and one that is nonpolar F. None of the above.

D. able to act as an acid and a base

____________ help(s) unfolded or misfolded proteins achieve their proper three-dimensional conformation. A. Endoplasmic reticulum B. foldylocks C. Ribosomes D. Ribonuclease E. Molecular chaperones

E. Molecular chaperones

Tertiary structure of macromolecules (e.g. proteins) can be determined using: A. X-ray crystallography. B. nuclear magnetic resonance spectroscopy. C. thin layer chromatography. D. All of the above answers are correct. E. Only A and B are correct.

E. Only A and B are correct.

The term amphipathic refers to those molecules that are: A. hydrophilic. B. hydrophobic. C. charged at both ends but with opposite charges. D. nonpolar at both ends. E. both hydrophilic at one end and hydrophobic at the other end.

E. both hydrophilic at one end and hydrophobic at the other end.

Particular groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity and solubility in aqueous solutions are known as: A. idiosyncratic groups B. aspirational groups C. amphoteric groups D. amphipathic groups E. functional groups

E. functional groups

Monomers are removed from polymers by ________ reactions. A. condensation B. substitution C. neutralization D. redox E. hydrolysis

E. hydrolysis

Carbon can form ________ covalent bonds. A. single B. double C. triple D. single and double E. single, double, and triple

E. single, double, and triple

Where are hydrophobic interactions most likely to occur? A. between two ions B. on the surface of a water-soluble protein C. in contact with water molecules D. between two charged molecules E. the core of a water-soluble protein

E. the core of a water-soluble protein