CHAPTER 8 Test Your Knowledge

Driving Question 1

By answering the questions below and studying Infographics 8.1 and 8.4, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

A protein is made up of a chain of __________.
a. nucleotides

b. amino acids

c. lipids

d. fatty acids

e. simple sugars

What determines a protein’s function?
a. the sequence of amino acids

b. the three-dimensional shape of the folded protein

c. the location of its gene on the chromosome

d. all of the above

e. a and b

USE IT

Heating a protein can cause it to denature, or unfold. What do you think would happen to the function of a protein in a denatured state? Explain your answer.

State two ways by which a person can be deficient in antithrombin activity. (Hint: Think of level of expression, which is driven by the regulatory sequence, and the amino acid sequence of the protein, which is determined by the coding sequence.)

Driving Question 2

By answering the questions below and studying Infographics 8.2, 8.5, 8.7, 8.8, 8.9, and 8.10, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

“A gene contains many chromosomes. Each chromosome encodes a protein.” Is this statement accurate? If not, explain why not, and rewrite it to make it correct.

What is the final product of gene expression?
a. a DNA molecule

b. an RNA molecule

c. a protein

d. a ribosome

e. an amino acid

For each structure or enzyme listed, indicate by N (nucleus) or C (cytoplasm) where it acts in the process of gene expression in a eukaryotic cell.

RNA polymerase_________

Ribosome _________

tRNA _________

mRNA _________

What is the product of transcription?
a. a gene

b. a protein

c. RNA

d. a chromosome

e. RNA polymerase

A gene has the sequence ATCGATTG. What is the sequence of the complementary RNA?
a. ATCGATTG

b. TACGTAAC

c. GTTAGCTA

d. UAGCUAAC

e. CAAUCGAU

USE IT

If someone has reduced levels of normal functioning antithrombin, would you suspect a problem in the regulatory or in the coding sequence of the antithrombin gene? Explain your answer.

If you wanted to use genetic engineering to increase the amount of antithrombin that someone produces, would you modify the regulatory sequence or the coding sequence? Explain your answer.

A change in DNA sequence can affect gene expression and protein function. What would be the impact of each of the following changes? How, specifically, would each change affect protein or mRNA structure, function, and levels?
a. a change that prevents RNA polymerase from binding to a gene’s regulatory sequence

b. a change in the coding sequence that changes the amino acid sequence of the protein

c. a change in the regulatory sequence that allows transcription to occur at much higher levels

d. a combination of the changes in b and c

Driving Question 3

By answering the questions below and studying Infographics 8.5, 8.6, and 8.7, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

Why is recombinant protein production in milk of transgenic animals an efficient strategy?
a. because milk is secreted, so the protein can be obtained noninvasively

b. because milk is produced in relatively large quantities

c. because mammary glands naturally secrete large quantities of proteins into milk

d. because milk is easier to obtain than other secretions (e.g., urine, sweat, and saliva)

e. all of the above

In an antithrombin-producing transgenic goat,
a. is the antithrombin gene construct present in every cell, or only in mammary cells? Explain your answer.

b. is the antithrombin gene construct expressed in every cell, or only in mammary cells? Explain your answer.

Explain why scientists used the beta-casein regulatory sequence to express human antithrombin in goats’ milk.

USE IT

Melanin is a pigment expressed in skin cells; melanin gives skin its color. If you wanted to express a different gene in skin cells, which part of the melanin gene would you use? Why? If you wanted to produce melanin in yeast cells, what part of the melanin gene would you use? Why?

Lysozyme is a protein secreted in tears and saliva in all mammals. Amylase is a protein secreted in mammalian saliva.
a. Describe the recombinant gene that you would assemble to express recombinant human insulin in the tears of goats.

b. Describe the recombinant gene that you would assemble to express recombinant human antithrombin in goat saliva.

c. Is either of these approaches as practical as protein production in milk? Why or why not?

Driving Question 4

By answering the questions below and studying Infographics 8.3, 8.5, and 8.6, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

Goat’s milk is used to produce cheese that humans can eat. How is this application of goat’s milk for human use different from the one described in this chapter?

Why are biotechnology companies eager to design genetically modified organisms to express therapeutic proteins, particularly ones that would otherwise have to be isolated from blood products (e.g., human antithrombin) or animal organs (e.g., insulin, originally isolated from pig pancreas)? (Hint: Consider cost, safety, and practicality.)

USE IT

Type 1 diabetes results from a loss of insulin production from the pancreas. People with diabetes take recombinant human insulin expressed in bacteria.
a. Describe the gene construct necessary for expression of human insulin in bacteria.

b. Describe the gene construct necessary to produce human insulin in goat’s milk.

c. If you were to attempt gene therapy (genetically modifying the human’s genome so that they can produce their own insulin), would you need a recombinant form of the insulin gene? Explain your answer.