mmsc490 exam 1 practice quiz 2

Proteins are polymers of how many different amino acids? 16 20 24 36

20

Common factors affecting the fluidity of a membrane include: number of double bonds in the fatty acid chains. temperature. length of the phospholipid fatty acid chains. All of the above

All of the above

Lipids play a major role in cells as components of cell membranes. part of the cell signaling function. a form of energy storage. All of the above

All of the above

Nucleotides have an important function in cells as: building blocks for nucleic acids. intracellular signal molecules. carriers of chemical energy. All of the above

All of the above

RNA in cells can serve as a: regulator of gene expression. carrier of information from the nucleus to the cytoplasm. catalyst or enzyme. All of the above

All of the above

Which of the following are involved in forming the tertiary structure of proteins? H bonds Ionic bonds Hydrophobic interactions All of the above

All of the above

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

Arginine

Which of the following is not one of the ways in which DNA differs from RNA? DNA is usually a double-stranded molecule. DNA contains thymine as one of its bases. DNA can form hydrogen bonds with complementary sequences. DNA contains deoxyribose sugars.

DNA can form hydrogen bonds with complementary sequences.

The scientist who first determined the complete amino acid sequence of a protein (insulin) was: Frederick Sanger. Christian Anfinsen. Linus Pauling.

Frederick Sanger.

In DNA, G pairs with C and A pairs with T. G pairs with C and U pairs with A. G pairs with T and A pairs with C. G pairs with A and C pairs with T.

G pairs with C and A pairs with T.

Which of the following is not a basic amino acid? Histidine Glutamine Arginine All of the above are basic amino acids.

Glutamine

What is the effect of a beta barrel on the permeability of a membrane? It increases permeability. beta barrels are never found in membranes. It has no effect. It decreases permeability.

It increases permeability.

Which of the following store most chemical energy per unit weight? Lipids Nucleic acids Proteins Carbohydrates

Lipids

Transport across biological membranes is speeded by what class of biological molecules? Proteins Carbohydrates Nucleic acids Lipids

Proteins

What is the major carbohydrate-storage molecule in plants? Cellulose Deoxyribonucleic acid Glycogen Starch

Starch

Which of the following is not one of the four major classes of organic molecules in the cell? Proteins Carbohydrates Lipids Water

Water

The three-dimensional structure of a protein is analyzed most definitively by electron microscopy. light microscopy. X-ray crystallography. subcellular fractionation.

X-ray crystallography.

Molecules that are partly water-soluble and partly water-insoluble are hydrophobic. amphipathic. allosteric. hydrophilic.

amphipathic.

Steroid hormones are derivatives of: sugars. phospholipids. cholesterol. amino acids.

cholesterol.

Cholesterol affects the fluidity of membranes by: increasing membrane fluidity at high temperatures and decreasing membrane fluidity at low temperatures. decreasing membrane fluidity at high temperatures and increasing membrane fluidity at low temperatures. decreasing membrane fluidity at all temperatures. increasing membrane fluidity at all temperatures.

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 almost completely surrounded by membrane lipid. weakly held in place on the surface of the lipid bilayer. embedded nearly randomly in the lipid bilayer. segregated into large protein clusters or rafts.

embedded nearly randomly in the lipid bilayer.

Cholesterol, a membrane lipid in animals, has a chemical structure similar to estradiol. phosphatidylinositol. thymine. triacylglycerol.

estradiol.

Sugars can cyclize if they contain .......... or more carbons. five four six seven

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 serine. glyceraldehyde. glycerol. dihydroxyacetone.

glycerol.

In polysaccharides, sugars are linked together by means of .......... bonds. phosphodiester glycosidic hydrophobic peptide

glycosidic

Complementary base pairs form .......... bonds to direct replication of DNA. glycosidic phosphodiester covalent hydrogen

hydrogen

Lipids with unsaturated fatty acids increase the charge associated with the inner face of a membrane. decrease the fluidity of membranes. increase the fluidity of membranes. are present only on the inner side of the plasma membrane.

increase the fluidity of membranes.

Introducing a double bond into a fatty acid has the effect of putting a(n) .......... into the conformation of the molecule. reinforcing rod amino acid bulge kink reverse spiral

kink

A few sugars joined together are called a(n) oligosaccharide. polysaccharide. glycoside. starch.

oligosaccharide.

An amphipathic molecule is hydrophilic. part water-soluble and part water-insoluble. water-soluble. water-insoluble.

part water-soluble and part water-insoluble.

In the primary structure of a protein, amino acids are joined together by .......... bonds. peptide hydrophobic glycosidic phosphodiester

peptide

The most common molecules in cellular membranes are the: proteins. phospholipids. glycolipids. cholesterol molecules.

phospholipids.

Serine, threonine, asparagine, and glutamine are all .......... amino acids. acidic polar basic nonpolar

polar

The unique properties of different membranes are primarily a function of their: glycolipids. proteins. cholesterol molecules. phospholipids.

proteins.

The interaction of the α and β subunits to form the hemoglobin molecule is an example of .......... structure. quaternary tertiary secondary primary

quaternary

Sphingomyelin contains two hydrocarbon chains linked to serine. choline. glycerol. glycine.

serine.

Fatty acids are stored in fat droplets in the form of phospholipids. triacylglycerols. cholesterol. glycolipids.

triacylglycerols.

The most abundant molecules in cells are proteins. lipids. water. carbohydrates.

water.

The major bonds in glycogen are .......... glycosidic bonds. β(1→4) α(1→6) α(1→4) β(1→6)

α(1→4)