Mastering Bio 3800 Ch.3

Based on the principle of complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________. A; T T; C T; G A; C

A; T

Many cell biologists claim that monosaccharides are older (chronologically and evolutionarily) than nucleotides. Which of the following observations supports this hypothesis? Nucleotides have more chemically complicated structures than monosaccharides. All nucleotides contain monosaccharides. Monosaccharides are metabolized by cells to make nucleotides (i.e., glucose is metabolized by the enzymes of glycolysis to make ATP). All of the other answer choices support this hypothesis.

All of the other answer choices support this hypothesis.

The primary structure of a protein is simply the order of amino acids from one end of the protein to another. is the linear sequence of amino acids that are linked together by peptide bonds. is important both genetically and structurally. is important for determining the secondary and tertiary structure of a protein. All of these statements are true.

All of these statements are true.

In the accompanying image, a nucleotide is indicated by the letter _____. C- Double strand of DNA D- single strand of DNA A- DNA E - none of the above B- guanine

B

A nitrogenous base is indicated by the letter _____. E-non of the above D- 1' carbon C- base B-nucleotide A-phosphate group

C

Which of these is a difference between a DNA and an RNA molecule? DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars. DNA is a polymer composed of nucleotides, whereas RNA is a polymer composed of nucleic acids. DNA contains nitrogenous bases, whereas RNA contains phosphate groups. DNA contains uracil, whereas RNA contains thymine. DNA is double-stranded, whereas RNA is single-stranded.

DNA is double-stranded, whereas RNA is single-stranded.

What amino acid is present? And what is the level of structure for each? peptide hydrogen hydrophobic ionic disulfide

Peptide -Amino acids: all -level of structure: primary Hydrogen -amino acids: all -Level of structure: secondary Hydrophobic -amino acids: leucine Level of structure: Tertiary, Quaternary Ionic -amino acids: glutamate -level of structure: Tertiary, Quaternary Disulfide -amino acids: Cysteine -Level of structure: Tertiary, Quaternary

Two proteins associated with a rare neurodegenerative disorder have been sequenced. Protein A contains many polar amino acids with small regions containing nonpolar, hydrophobic amino acids. Protein B is rich in nonpolar, hydrophobic amino acids with only two small regions containing polar amino acids. What might this suggest about the two proteins? The two proteins may have different secondary structures. Protein A is fibrous and Protein B is globular. Protein A may be a cytoplasmic protein and Protein B may be a membrane associate protein. Protein A and Protein B are complementary parts of a supramolecular structure. Protein A is most likely and enzyme and Protein B is most likely a storage protein.

Protein A may be a cytoplasmic protein and Protein B may be a membrane associate protein.

Cellulose, chitin, and the polysaccharide that makes up the cell walls of many bacteria are the structural polysaccharides, whereas starch and glycogen are the main storage polysaccharides. What must be true about these two classes of polysaccharides? The alpha-glycosidic bonds of storage polysaccharides are less stable than the beta-glycosidic bonds of structural polysaccharides. The beta-glycosidic bonds of storage polysaccharides are less stable than the alpha-glycosidic bonds of structural polysaccharides. The beta-glycosidic bonds of storage polysaccharides are more stable than the alpha-glycosidic bonds of structural polysaccharides. In addition, chemical stability correlates with permanence or nonreactivity. Which of the two types of polysaccharides would be expected to remain the same for longer? The alpha-glycosidic bonds of storage polysaccharides are more stable than the beta-glycosidic bonds of structural polysaccharides.

The alpha-glycosidic bonds of storage polysaccharides are less stable than the beta-glycosidic bonds of structural polysaccharides.

Can you suggest an explanation for naturally curly hair? There is probably a genetic difference in the positioning of serine groups and hence in the formation of disulfide bonds. There are probably no disulfide bonds in α-keratin molecules. There is probably a genetic difference in the positioning of cysteine groups and hence in the formation of disulfide bonds. There are probably no disulfide bonds in β-keratin molecules.

There is probably a genetic difference in the positioning of cysteine groups and hence in the formation of disulfide bonds.

The term amphipathic describes the characteristic of some molecules that have ________. two polar regions both a polar and a nonpolar region no polar regions only a single polar region two nonpolar regions

both a polar and a nonpolar region

Which of these illustrates the secondary structure of a protein? (photos not shown) a) quatranery structure b) tertiary structure c) secondary structure d) Amino acid e) peptide chain

c) secondary structure

The secondary structure of a protein results from _____. peptide bonds bonds between sulfur atoms hydrogen bonds ionic bonds hydrophobic interactions

hydrogen bonds

What are the three general types of amino acids? acidic, basic, and neutral covalent, noncovalent, and van der Waals forces α helices, β sheets, and looped segments hydrophobic, polar (noncharged), polar (charged) positive, negative, and noncharged

hydrophobic, polar (noncharged), polar (charged)

Several different kinds of bonds or interactions are involved in generating and maintaining the structure of proteins. List five such bonds or interactions. Select the five correct answers. phosphodiester bond ionic bond disulfide bond hydrogen bond metallic bond coordination bond glycosidic bond peptide bond hydrophobic bond

ionic bond disulfide bond hydrogen bond peptide bond hydrophobic bond

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____. phosphate group, not a uracil double-stranded molecule, not a single-stranded molecule sugar with two, and not three, oxygen atoms uracil nitrogenous base, not a thymine nitrogenous base thymine nitrogenous base, not a uracil nitrogenous base

sugar with two, and not three, oxygen atoms

The function of triglycerides is to store energy. to form semipermeable membranes. to transport substances in and out of cells. store information. to form semipermeable membranes and to transport substances in and out of cells.

to store energy.

For each of the following features of nucleic acids, indicate whether it is true of DNA only, of RNA only, of both DNA and RNA, or of neither. (True of DNA only) True of RNA only (True of both DNA and RNA) (True of neither) Contains the nucleotide deoxythymidine monophosphate. Is involved in the process of protein synthesis in the cytoplasm of the cells in the liver. Contains the base adenine Occurs only in single-stranded form. Is synthesized by a process that involves base pairing. Is an inherently directional molecule, with an N-terminus on one end and a C-terminus on the other end.

(True of DNA only) Contains the nucleotide deoxythymidine monophosphate. (True of RNA only) Is involved in the process of protein synthesis in the cytoplasm of the cells in the liver. (True of both DNA and RNA) Contains the base adenine. Is synthesized by a process that involves base pairing. (True of neither) Occurs only in single-stranded form. Is an inherently directional molecule, with an N-terminus on one end and a C-terminus on the other end.

Which of the following accurately describes the structure of fibrous proteins? Fibrous proteins are usually composed of either α helices or β sheets throughout the molecule, giving them a highly ordered, repetitive structure. Fibrous proteins have a simple primary structure and very little secondary structure, resulting in long, thin fibers. Fibrous proteins are composed of an equal mixture of α helices and β sheets with interconnecting looped segments. Fibrous proteins usually contain a number of different domains with different structural motifs. Fibrous proteins have an extensive tertiary and quaternary structure that affects the strength and elasticity of each fiber.

Fibrous proteins are usually composed of either α helices or β sheets throughout the molecule, giving them a highly ordered, repetitive structure.

Why do you suppose a permanent isn't permanent? Hair continues to grow, and the new α-keratin molecules will have the natural (correct) disulfide bonds. Hair continues to grow, and the new α-keratin molecules will not have any disulfide bonds. Disulfide bonds occasionally break and re-form spontaneously, allowing the hair proteins to return gradually to their original, thermodynamically more favorable shape. Peptide bonds occasionally break and re-form spontaneously, allowing the hair proteins to return gradually to their original, thermodynamically more favorable shape.

Hair continues to grow, and the new α-keratin molecules will have the natural (correct) disulfide bonds. Disulfide bonds occasionally break and re-form spontaneously, allowing the hair proteins to return gradually to their original, thermodynamically more favorable shape.

What is the chemical basis of a permanent? peptide amide cysteine ionic tertiary tyrosine alanine disulfide primary primary Hair proteins are first treated with a sulfhydryl reducing agent to break _________ bonds and thereby destroy much of the natural _______ structure and shape of the hair. After being set in the desired shape, the hair is treated with an oxidizing agent to allow the bonds to re-form between different _______ groups, as determined by the positioning imposed by the curlers.

Hair proteins are first treated with a sulfhydryl reducing agent to break (disulfide) bonds and thereby destroy much of the natural (tertiary) structure and shape of the hair. After being set in the desired shape, the hair is treated with an oxidizing agent to allow the bonds to re-form between different (cysteine) groups, as determined by the positioning imposed by the curlers.

What is the advantage of the respective properties in each case? The rigid, fibrous structure of ________ and its virtual _________ in water make this polymer a suitable _____________, and the _______ flexible structure of ______and its _______ solubility in water make this polymer a suitable ____________.

The rigid, fibrous structure of (cellulose) and its virtual (insolubility) in water make this polymer a suitable (component of the plant cell wall), and the (more) flexible structure of (starch) and its (greater) solubility in water make this polymer a suitable (storage macromolecule.)

A cotton fiber consists almost exclusively of cellulose, whereas a potato tuber contains mainly starch. Cotton is tough, fibrous, and virtually insoluble in water. The starch present in a potato tuber, on the other hand, is neither tough nor fibrous and can be dispersed in hot water to form a turbid solution. Yet both the cotton fiber and the potato tuber consist primarily of polymers of D-glucose in (1\rightarrow4) linkage. Part A How can two polymers consisting of the same repeating subunit have such different properties? The two polymers have very different properties because they differ in structure as a result of different molecular mass. Low molecular mass of cellulose gives it a rigid, fibrous structure not seen in starch, which has high molecular mass. The two polymers have very different properties because they differ in structure as a result of different molecular mass. High molecular mass of cellulose gives it a rigid, fibrous structure not seen in starch, which has low molecular mass. The two polymers have very different properties because they differ in structure as a result of differing (1---->4) linkages between glucose monomers. The beta(1 ---> 4) linkage of cellulose gives it a rigid, fibrous structure not seen in starch, which has an alpha(1 ---> 4) linkage between glucose monomers. The two polymers have very different properties because they differ in structure as a result of differing 1 ----> 4 linkages between glucose monomers. The \alpha(1------> 4) linkage of cellulose gives it a rigid, fibrous structure not seen in starch, which has an beta(1 ----> 4) linkage between fructose monomers.

The two polymers have very different properties because they differ in structure as a result of differing (1---->4) linkages between glucose monomers. The beta(1 ---> 4) linkage of cellulose gives it a rigid, fibrous structure not seen in starch, which has an alpha(1 ---> 4) linkage between glucose monomers.

Which of the following has the greatest number of glycosidic bonds? glucose amylose vitamin A DNA triacylglycerol

amylose

is an image of a(n) _____. (phosphate group, 5 carbon sugar, base) thiol nucleotide nucleic acid amino acid none of the above

nucleotide

The letter A indicates a _____. (PO4) sugar phosphate group none of the above nitrogenous base nucleotide

phosphate group