MMSC 490 Practice Quiz 2

RNA in cells can serve as a

catalyst or enzyme, regulator of gene expression, and carrier of information from the nucleus to the cytoplasm

Cholesterol, a membrane lipid in animals, has a chemical structure similar to

estradiol

Sugars can cyclize if they contain _________ or more carbons

five

Phospholipids consist of a 3-carbon core to which fatty acids and a phosphate group are linked. The most common 3-carbon core is

glycerol

In polysaccharides, sugars are linked together by means of ________ bonds

glycosidic

Complementary base pairs from ___________ bonds to direct replication of DNA

hydrogen

Lipids with unsaturated fatty acids

increase the fluidity of membranes

A few sugars joined together are called

oligosaccharide

Sphingomyelin contains two hydrocarbon chains linked to

serine

What is the major carbohydrate-storage molecule in plants?

starch

Fatty acids are stored in fat droplets in the form of

triacylglycerols

The most abundant molecules in cells are

water

Which of the following is not one of the four major classes of organic molecules in the cell?

water (lipids, proteins, and carbohydrates are major classes)

Proteins are polymers of how many different amino acids?

20

Proteins can be covalently modified by the addition of phosphate groups to all but which of the following amino acids?

Arginine

Which of the following is not one of the ways in which DNA differs from RNA?

DNA can form hydrogen bonds with complementary sequences

In DNA

G pairs with C and A pairs with T

Nucleotides have an important function in cells as

carriers of chemical energy, intracellular signal molecules, and building blocks for nucleic acids

Cholesterol affects the fluidity of membranes by

decreasing membrane fluidity at high temperatures and increasing membrane fluidity at low temperatures

In the fluid mosaic model of biological membrane structure, transmembrane proteins are

embedded nearly randomly in the lipid bilayer

What is the effect of a beta barrel on the permeability of a membrane?

it increases permeability

Introducing a double bond into a fatty acid has the effect of putting a(n) _______ into the conformation of the molecule.

kink

Which of the following store most chemical energy per unit weight?

lipids

Lipids play a major role in cells as

part of cell signaling function, components of the cell membranes, and a form of energy storage

In the primary structure of a protein amino acids are joined together by ___________ bonds.

peptide

The most common molecules in cellular membranes are the

phospholipids

Serine, threonine, asparagine, and glutamine are all __________ amino acids

polar

The unique properties of different membranes are primarily a function of their

proteins

Transport across biological membranes is speeded by what class of biological molecules

proteins

The interaction of the a and b subunits to form the hemoglobin molecule is an example of _______ structure

quaternary

Common factors affecting the fluidity of a membrane include

temperature, number of double bonds in the fatty acid chains, and length of the phospholipid fatty acid chains

Which of the following are involved in forming the tertiary structure of proteins?

Hydrophobic interactions, ionic bonds, and H bonds

The three-dimensional structure of a protein is analyzed most definitively by

X-ray crystallography

The major bonds in glycogen are __________ glycosidic bonds

a(1->4)

Molecules that are partly water-soluble and partly water-insoluble are

amphipathic