Biology: Concepts and Investigations

Mariëlle Hoefnagels

Chapter 7

DNA Structure and Gene Function - all with Video Answers

Educators

Chapter Questions

Problem 1

Describe the three-dimensional structure of DNA.

Aditya Sood

Aditya Sood

Numerade Educator

Problem 2

How would the results of the Hershey-Chase experiment have differed if protein were the genetic material?

Wade Corn

Numerade Educator

Problem 3

Write the complementary DNA sequence of each of the following base sequences:
a. $\mathrm{T} \mathrm{CG}$ A GA $\mathrm{A}$ T $\mathrm{CT}$ C G A T T
b. $C C G$ T $A$ T $A G C C G G T A C$
c. $A T C G G A T C G C T A C T G$

Aditya Sood

Numerade Educator

Problem 4

Put the following in order from smallest to largest: nucleotide, genome, nitrogenous base, gene, nucleus, cell, codon, chromosome.

Bryan Valdivia

Numerade Educator

Problem 5

What is the function of DNA?

Aditya Sood

Numerade Educator

Problem 6

List the differences between RNA and DNA.

Aditya Sood

Numerade Educator

Problem 7

Define and distinguish between transcription and translation. Where in a eukaryotic cell does each process occur?

Aditya Sood

Numerade Educator

Problem 8

This chapter compared a chromosome to a cookbook and a gene to a recipe. List the ways that chromosomes and genes are UNLIKE cookbooks and recipes.

Aditya Sood

Numerade Educator

Problem 9

Some people compare DNA to a blueprint stored in the office of a construction company. Explain how this analogy would extend to transcription and translation.

Aditya Sood

Numerade Educator

Problem 10

List the three major types of RNA and their functions.

Aditya Sood

Numerade Educator

Problem 11

List the sequences of the mRNA molecules transcribed from the following template DNA sequences:
a. $\mathrm{T}$ T $\mathrm{A}$ C $\mathrm{A}$ C $\mathrm{T}$ T $\mathrm{G}$ C $\mathrm{T}$ T $\mathrm{G}$ A G $\mathrm{A}$ G $\mathrm{T}$ ?
b. $G$ G $A$ A T $A$ C $G$ T $C$ T $A$ G $C$ T $A$ G $C$ A

Aditya Sood

Numerade Educator

Problem 12

Given the following partial mRNA sequences, reconstruct the corresponding DNA template sequences:
a. $G U G G C G U A U U C U U U U C C G G G U A G G$
b. $\mathrm{A} \mathrm{G}$ G $\mathrm{A}$ A $\mathrm{A}$ A $\mathrm{C} \mathrm{C} \mathrm{C} \mathrm{C} \mathrm{U} \mathrm{C} \mathrm{U}$ U $\mathrm{A}$ U $\mathrm{U}$ A $\mathrm{U}$ A $\mathrm{G}$ A $\mathrm{U}$

Bryan Valdivia

Numerade Educator

Problem 13

Refer to the figure to answer these questions:
a. Add labels for mRNA (including the $5^{\prime}$ and $3^{\prime}$ ends) and tRNA. In addition, draw in the RNA polymerase enzyme and the ribosomes, including arrows indicating the direction of movement for each.
b. What are the next three amino acids to be added to peptide $b$ ?
c. Fill in the nucleotides in the mRNA complementary to the template DNA strand.
d. What is the sequence of the DNA complementary to the template strand (as much as can be determined from the figure)?
e. Does this figure show the entire peptide that this gene encodes? How can you tell?
f. What might happen to peptide $b$ after its release from the ribosome?
g. Does this figure depict a prokaryotic or a eukaryotic cell? How can you tell?

Scott Rhodes

Numerade Educator

Problem 14

Consult the genetic code to write codon changes that could account for the following changes in amino acid sequence.
a. tryptophan to arginine
b. glycine to valine
c. tyrosine to histidine

Bryan Valdivia

Numerade Educator

Problem 15

Titin is a muscle protein whose gene has the largest known coding sequence: 80,781 DNA bases. How many amino acids long is titin?

Aditya Sood

Numerade Educator

Problem 16

If a protein is 1259 amino acids long, what is the minimum size of the gene that encodes the protein? Why might the gene be longer than the $\operatorname{minimum} ?$

Bryan Valdivia

Numerade Educator

Problem 17

On the television program The X Files, Agent Scully discovers an extraterrestrial life form that has a triplet genetic code but with five different bases instead of the four of earthly inhabitants. How many different amino acids can this code specify?

Eleanor Behling

Eleanor Behling

Numerade Educator

Problem 18

A mouse's genome has 1500 olfactory genes encoding proteins that enable the animal to detect odors. In each olfactory sensory neuron, only one of these genes is expressed; the others remain "off." List all of the ways that a mouse cell might silence the unneeded genes.

Lucas Finney

Numerade Educator

Problem 19

The genome of the human immunodeficiency virus (HIV) includes nine genes. Two of the genes encode four different proteins each. How is this possible?

DJ

David Johnson

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Problem 20

The shape of a finch's beak reflects the expression of a gene that encodes a protein called calmodulin. A cactus finch has a long, pointy beak; its cells express the gene more than a ground finch, which has a short, deep beak. When researchers boosted gene expression in a ground finch embryo, the bird's upper beak was longer than normal. Develop a hypothesis that explains this finding.

Mark Tingey

Numerade Educator

Problem 21

If a gene is like a cake recipe, then a mutation is like a cake recipe containing an error. List the major types of mutations, and describe an analogous error in a cake recipe.

Aditya Sood

Numerade Educator

Problem 22

A protein-encoding region of a gene has the following DNA sequence:
$\mathrm{G} \mathrm{T}$ A $\mathrm{G} \mathrm{C}$ G $\mathrm{T}$ CA $\mathrm{C}$ A $\mathrm{A}$ A $\mathrm{C}$ A $\mathrm{A}$ A $\mathrm{T}$ C $\mathrm{A}$ G $\mathrm{C}$ T $\mathrm{C}$
Determine how each of the following mutations alters the amino acid sequence:
a. substitution of a T for the $C$ in the 10 th position
b. substitution of a G for the $C$ in the 19 th position
c. insertion of a T between the 4 th and 5 th DNA bases
d. insertion of a GTA between the 12 th and 13th DNA bases
e. deletion of the first DNA nucleotide

Marisa A

Numerade Educator

Problem 23

Explain how a mutation in a protein-encoding gene, an enhancer, or a gene encoding a transcription factor can all have the same effect on an organism.

Mark Tingey

Numerade Educator

Problem 24

How can a mutation alter the sequence of DNA bases in a gene but not produce a noticeable change in the gene's polypeptide product? How can a mutation alter the amino acid sequence of a polypeptide yet not alter the organism?

Aditya Sood

Numerade Educator

Problem 25

Parkinson disease causes rigidity, tremors, and other motor symptoms. Only $2 \%$ of cases are inherited, and these tend to have an early onset of symptoms. Some inherited cases result from mutations in a gene that encodes the protein parkin, which has 12 exons. Indicate whether each of the following mutations in the parkin gene would result in a smaller protein, a larger protein, or no change in the size of the protein.
a. deletion of exon 3
b. deletion of six consecutive nucleotides in exon 1
c. duplication of exon 5
d. disruption of the splice site between exon 8 and intron 8
e. deletion of intron 2

Mark Tingey

Numerade Educator

Problem 26

In a disorder called gyrate atrophy, cells in the retina begin to degenerate in late adolescence, causing night blindness that progresses to total blindness. The cause is a mutation in the gene that encodes an enzyme, ornithine aminotransferase (OAT). Researchers sequenced the $O A T$ gene for five patients with the following results:
Patient A: A change in codon 209 of UAU to UAA
Patient B: A change in codon 299 of UAC to UAG
Patient C: A change in codon 426 of CGA to UGA
. Patient D: A two-nucleotide deletion at codons 64 and 65 that results in a UGA codon at position 79
. Patient E: Exon 6, including 1071 nucleotides, is entirely deleted.
a. Which patient(s) have a frameshift mutation?
b. How many amino acids is patient E missing?
c. Which patient(s) will produce a shortened protein?

Mark Tingey

Numerade Educator

Problem 27

Researchers use computer algorithms that search DNA sequences for indications of specialized functions. Explain the significance of detecting the following sequences:
a. a promoter
b. a sequence of 75 to 80 nucleotides that folds into a shape resembling a backwards letter "L"
c. a gene with a sequence very similar to that of a known proteinencoding gene but that is not translated into protein
d. RNAs with poly A tails

Mark Tingey

Numerade Educator

Problem 28

How do researchers create recombinant DNA and transgenic organisms, and what are some applications of this technology?

Ramesh Singh

Numerade Educator

Problem 29

Transgenic crops often require fewer herbicides and insecticides than conventional crops. In that respect, they could be considered environmentally friendly. Use the Internet to research the question of why some environmental groups oppose transgenic technology.

John Noonan

Numerade Educator

Problem 30

Define gene therapy, antisense $R N A,$ gene knockout, and DNA microarray.

Sam Limsuwannarot

Sam Limsuwannarot

Numerade Educator

Problem 31

Which hiotechnology might be able to accomplish the following goals? More than one answer may be possible.
a. Silence the HIV genes integrated into the chromosomes of people with HIV infection (which leads to AIDS).
b. Create bacteria that produce human growth hormone, used to treat extremely short stature.

Hast Aggarwal

Numerade Educator

Problem 32

Explain the ethical issues that gene therapy presents.

Aditya Sood

Numerade Educator

Problem 33

Many patients waste precious time taking anticancer drugs that are ineffective or too toxic. How might DNA microarray technology refine the treatment of cancer?

Bryan Valdivia

Numerade Educator

Problem 34

A young zebra finch must learn to sing. Researchers used a modified virus to deliver a "mirror image" of the $F O X P 2$ gene to the brain of a young finch. With the $F O X P 2$ gene silenced, the bird's song-learning ability was impaired. Why did the treatment silence the gene? How does this experiment relate to the study of human language?

Heidi Luczynski

Heidi Luczynski

Numerade Educator

Problem 35

Choose an experiment mentioned in the chapter and analyze how it follows the scientific method.

David Collins

Numerade Educator

Problem 36

Give an example from the chapter of different types of experiments used to address the same hypothesis. Why might this be necessary?

Amy Jiang

Numerade Educator