Study Quiz #2

The following questions are based on the 15 molecules illustrated below. Each molecule may be used once, more than once, or not at all. Which of the following combinations could be linked together to form a nucleotide? 1, 2, and 11 3, 7, and 8 5, 9, and 10 11, 12, and 13 12, 14, and 15

11, 12, and 13

Which of the following statements is false? 1 and 4 could be joined together by a glycosidic linkage to form a disaccharide. 9 and 10 could be joined together by ester bonds to form a triacylglycerol. 2 and 7 could be joined together to form a short peptide. 2, 7, and 8 could be joined together to form a short peptide. 14 and 15 could be joined together to form a polypeptide.

14 and 15 could be joined together to form a polypeptide.

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine? Answers: 10 20 40 80 Impossible to tell from the information given

40

Which molecule has hydrophilic and hydrophobic properties and would be found in plasma membranes? 1 5 6 12 14

5

The sequence of nucleotides in one polynucleotide strand of the DNA double helix is: 5'-G A A T T C -3' The sequence of nucleotides in the opposite strand is going to be: Answers: 5'-C T T A A G -3' 5'-G A A T T C -3' 5'-C U U A A G -3' 5'-G A A U U C -3'

5'-G A A T T C -3'

Which of the following show the prevalent structure of monosaccharides in aqueous solution?1 and 2 6 and 12 6, 12 and 15 1, 4 and 6 6, 12 and 13

6 and 12

The R group of the amino acid serine is —CH2—OH. The R group or side chain of the amino acid alanine is —CH3. Where would you expect to find these amino acids in a globular protein in aqueous solution? Serine would be in the interior, and alanine would be on the exterior of the globular protein. Alanine would be in the interior, and serine would be on the exterior of the globular protein. Both serine and alanine would be in the interior of the globular protein. Both serine and alanine would be on the exterior of the globular protein. Both serine and alanine would be in the interior and on the exterior of the globular protein.

Alanine would be in the interior, and serine would be on the exterior of the globular protein.

Which of the following is true regarding the alpha and beta forms of glucose? Alpha glucose is only found in plants and beta glucose is only found in animals. Alpha glucose is found in DNA, beta glucose is found in RNA Alpha and beta glucose are enantiomers of one another. Alpha and beta glucose are structural isomers of one another Only alpha glucose can be polymerized to form a polysaccharide.

Alpha and beta glucose are enantiomers of one another.

Refer to Figure 1 to answer the following: At which bond would water need to be added to achieve hydrolysis of the peptide, back to its component amino acids? Answers: A B C D E

C

In comparing amino acid sequences of the same protein in different species, an amino acid substitution that replaces an amino acid with one having similar chemical characteristics is referred to as __. A mutation Invariant residue Hypervariable regions Conservative substitution Polarity shift

Conservative Subsititution

Which of the following is not a known function that can be ascribed to cellular or viral RNAs? Contains hereditary information. Control of gene expression. Enzymatic activity. Energy storage. Specifying the primary structure of a protein.

Energy Storage

Which, if any, of the following types of chemical interactions contribute to the structural stability of the DNA double helix?Hydrogen bonding between sugar and phosphate groups Hydrogen bonding between nitrogenous bases Covalent bonding between nitrogenous bases Ionic interactions between the sugar and phosphate groups Ionic interactions between the nitrogenous bases More than one of these contributes to DNA's structural stability.

Hydrogen bonding between nitrogenous bases

DNase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNase? The two strands of the double helix would separate. The phosphodiester bonds between deoxyribose sugars would be broken. The purines would be separated from the deoxyribose sugars. The pyrimidines would be separated from the deoxyribose sugars. All bases would be separated from the deoxyribose sugars.

The phosphodiester bonds between deoxyribose sugars would be broken.

Which of the following is/are expected consequence(s) of changing one amino acid in a polypeptide consisting of 325 amino acids? Only the primary structure of the polypeptide would be changed. The primary structure would definitely change, the secondary structure of the polypeptide might be changed. The primary structure would definitely change, both the secondary and tertiary structures of the polypeptide might be changed. The primary structure would definitely change, the secondary, tertiary and quaternary structures of the polypeptide might be changed. It is impossible to predict the effect on primary, secondary, tertiary or quaternary structure without more information, but the function of the protein would be disrupted.

The primary structure would definitely change, the secondary, tertiary and quaternary structures of the polypeptide might be changed.

Which of the following statements is false for the class of biological molecules known as lipids? Their hydrophilic nature makes them soluble in water. They are an important constituent of cell membranes. They contain more energy than proteins and carbohydrates. They are not true polymers. They contain waxes and steroids.

Their hydrophilic nature makes them soluble in water.

Question Which of the following statements regarding saturated fats is not true? They are more common in animals than in plants. They lack double bonds in the carbon chains of their fatty acids. They generally solidify at room temperature. They contain more hydrogen than unsaturated fats having the same number of carbon atoms. They are the most prevalent form of lipid found in cell membranes.

They are the most prevalent form of lipid found in cell membranes.

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA Answers: is a six-carbon sugar and the sugar in RNA is a five-carbon sugar. can form a double-stranded molecule. has a six-membered ring of carbon and nitrogen atoms. can attach to a phosphate. contains one less oxygen atom.

contains one less oxygen atom.

Which, if any, of the following type(s) of interactions directly stabilize(s) the alpha helix and the beta pleated sheet structures of proteins? hydrophobic interactions between backbone constituents hydrogen bonds between R group constituents covalent or ionic bonds between backbone constituents hydrogen bonds between backbone constituents peptide bonds between backbone constituents more than one of these types of interactions is responsible

hydrogen bonds between backbone constituents

A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism is more closely related to humans than to frogs. is more closely related to frogs than to humans. must have evolved from gibbons, not rats. is more closely related to humans than to rats. could have evolved from rats but not from humans and gibbons.

is more closely related to frogs than to humans

The tertiary structure of a protein is the bonding together of several polypeptide chains by weak bonds. order in which amino acids are joined in a polypeptide chain. unique three-dimensional shape of the fully folded polypeptide. organization of a polypeptide chain into an alpha helix or beta pleated sheet. > overall protein structure resulting from the aggregation of two or more polypeptide subunits.

unique three-dimensional shape of the fully folded polypeptide.