Comparisons of amino acid sequences can shed light on the

What are the four main classes of large biological molecules? Which class does not consist of polymers?

How many molecules of water are needed to completely hydrolyze a polymer that is ten monomers long?

Suppose you eat a serving of fish. What reactions must occur for the amino acid monomers in the protein of the fish to be converted to new proteins in your body?

What is the fundamental basis for the differences between carbohydrates, proteins, and nucleic acids?

Write the formula for a monosaccharide that has three carbons

A dehydration reaction joins two glucose molecules to form maltose. The formula for glucose is C6H12O6. What is the formula for maltose?

After a cow is given antibiotics to treat an infection, a vet gives the animal a drink of gut culture containing various prokaryotes. Why is this necessary?

Compare the composition, structure, and function of starch and cellulose. What role do starch and cellulose play in the human body?

Compare the structure of a fat (triglyceride) with that of a phospholipid.

Why are human sex hormones considered lipids?

Suppose a membrane surrounded an oil droplet, as it does in the cells of plant seeds. Describe and explain the form it might take.

Why are lipids not considered to be macromolecules or polymers?

Why does a denatured protein no longer function normally?

What parts of a polypeptide participate in the bonds that hold together secondary structure? Tertiary structure?

Where would you expect a polypeptide region that is rich in the amino acids valine, leucine, and isoleucine to be located in the folded polypeptide? Explain.

Proteins are the most structurally and functionally diverse class of biological molecules. Explain the basis for this diversity

Go to Figure 5.26a and, for the top three nucleotides, number all the carbons in the sugars, circle the nitrogenous bases, and star the phosphates.

In a DNA double helix, a region along one DNA strand has this sequence of nitrogenous bases: 5-TAGGCCT-3. Copy this sequence, and write down its complementary strand, clearly indicating the 5and 3ends of the complementary strand.

(a) Suppose a substitution occurred in one DNA strand of the double helix in question 2, resulting in 5-TAAGCCT-3 3-ATCCGGA-5 Copy these two strands, and circle and label the mismatched bases. (b) If the modified top strand is used by the cell to construct a complementary strand, what would that matching strand be?

What role does complementary base pairing play in the functions of nucleic acids?

Which of the following categories includes all others in the list? a. monosaccharide d. carbohydrate b. disaccharide e. polysaccharide c. starch

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the form. Which of the following could amylase break down? a. glycogen, starch, and amylopectin b. glycogen and cellulose c. cellulose and chitin d. starch and chitin e. starch, amylopectin, and cellulose

Which of the following statements concerning unsaturated fats is true? a. They are more common in animals than in plants. b. They have double bonds in the carbon chains of their fatty acids. c. They generally solidify at room temperature. d. They contain more hydrogen than do saturated fats having the same number of carbon atoms. e. They have fewer fatty acid molecules per fat molecule.

The structural level of a protein least affected by a disruption in hydrogen bonding is the a. primary level. d. quaternary level. b. secondary level. e. All structural levels are c. tertiary level equally affected.

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? a. The two strands of the double helix would separate. b. The phosphodiester linkages of the polynucleotide backbone would be broken. c. The purines would be separated from the deoxyribose sugars. d. The pyrimidines would be separated from the deoxyribose sugars. e. All bases would be separated from the deoxyribose sugars.

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions? a. C60H120O60 d. C60H100O50 b. C6H12O6 e. C60H111O51 c. C60H102O51

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA? a. 5-purine-pyrimidine-purine-pyrimidine-3with 3-purinepyrimidine-purine-pyrimidine-5 b. 5-AGCT-3with 5-TCGA-3 c. 5-GCGC-3with 5-TATA-3 d. 5-ATGC-3with 5-GCAT-3 e. All of these pairs are correct.

Construct a table that organizes the following terms, and label the columns and rows. phosphodiester linkages polypeptides monosaccharides peptide bonds triacylglycerols nucleotides glycosidic linkages polynucleotides amino acids ester linkages polysaccharides fatty acids

Copy the polynucleotide strand in Figure 5.26a and label the bases G, T, C, and T, starting from the 5end. Assuming this is a DNA polynucleotide, now draw the complementary strand, using the same symbols for phosphates (circles), sugars (pentagons), and bases. Label the bases. Draw arrows showing the 5 3direction of each strand. Use the arrows to make sure the second strand is antiparallel to the first. Hint: After you draw the first strand vertically, turn the paper upside down; it is easier to draw the second strand from the 5 toward the 3direction as you go from top to bottom.

Comparisons of amino acid sequences can shed light on the evolutionary divergence of related species. If you were comparing two living species, would you expect all proteins to show the same degree of divergence? Why or why not?

Suppose you are a research assistant in a lab studying DNAbinding proteins. You have been given the amino acid sequences of all the proteins encoded by the genome of a certain species and have been asked to find candidate proteins that could bind DNA. What type of amino acids would you expect to see in such proteins? Why?

Some amateur and professional athletes take anabolic steroids to help them bulk up or build strength. The health risks of this practice are extensively documented. Apart from health considerations, how do you feel about the use of chemicals to enhance athletic performance? Is an athlete who takes anabolic steroids cheating, or is such use part of the preparation required to succeed in competition? Explain.

Proteins, which have diverse functions in a cell, are all polymers of the same subunits amino acids. Write a short essay (100150 words) that discusses how the structure of amino acids allows this one type of polymer to perform so many functions.