Ch. 11 - Gene Expression and Epigenetics

Question 1

Hemoglobin is a protein that the blood that binds to and transports oxygen.

Answer 1

True

Question 2

A hemoglobin molecule is made of _____ polypeptide chain(s).

Answer 2

Four

Question 3

In the embryo, most hemoglobin molecules consist of _____.

Answer 3

Two epsilon chains and two zeta chains

Question 4

In the fetus, the expression of the epsilon and _____ chain(s) decreases.

Answer 4

Zeta

Question 5

In the fetus, the expression of the _____ chain increases.

Answer 5

Alpha

Question 6

Fetal hemoglobin consists of _____.

Answer 6

Two gamma chains and two alpha chains

Question 7

Adult hemoglobin consists of _____.

Answer 7

Two alpha chains and two beta chains

Question 8

Compared to adult blood, fetal blood carries _____ oxygen.

Answer 8

20-30% more

Question 9

MicroRNAs are typically about _____ bases long.

Answer 9

21

Question 10

MicroRNAs regulate gene expression at the level of _____.

Answer 10

Translation

Question 11

MicroRNAs are an example of _____ RNAs.

Answer 11

Noncoding

Question 12

The human genome contains approximately _____ distinct sequences of microRNAs.

Answer 12

2500

Question 13

MicroRNAs regulate approximately _____ of the protein-encoding genes in the human genome.

Answer 13

One third

Question 14

The human genome contains approximately _____ genes.

Answer 14

21,000

Question 15

Approximately _____ mRNAs can be produced from the information in the human genome.

Answer 15

100,000

Question 16

Approximately _____ proteins can be produced from the information in the human genome.

Answer 16

One million

Question 17

_____ explains how one gene can specify multiple mRNAs.

Answer 17

Alternative splicing

Question 18

Select all of the mechanisms that help to maximize gene expression.

Answer 18

Alternative splicing allows one gene to produce multiple mRNAs.

The intron in one gene’s template strand may form part of the coding strand of a second gene.

Proteins can be modified after translation by the addition of sugars or lipids.

Proteins may be cut after translation to yield two distinct products.

Question 19

Noncoding RNAs include all types of RNA except the _____.

Answer 19

Messenger RNAs

Question 20

A _____ is very similar in sequence to a protein-encoding gene and may be transcribed, but is not translated into protein.

Answer 20

Pseudogene

Question 21

An RNA virus uses an enzyme called _____ to copy its genetic material into DNA.

Answer 21

Reverse transcriptase

Question 22

A DNA sequence that can move to different locations within the genome is called a ______.

Answer 22

Transposon

Question 23

You work in a lab and you have discovered a brilliant method for targeted control of chromatin remodeling on a gene-by-gene basis. You are specifically interested in modifying the transcription of oncogenes, which are genes whose overexpression can lead to cancer. Select modifications you would make in cancer cells that are over expressing oncogenes.

Answer 23

Decrease acetylation of histones

Decrease phosphorylation of histones

Increase methylation of histones

Question 24

You are working in a lab trying to develop a treatment for a novel disease. The exact level of protein produced is very important in the progression of the disease, so you need a mechanism of protein control that allows very fine tuning. Which approach might be helpful in treating this disease?

Answer 24

Using microRNAs to fine-tune protein levels

Question 25

β thalassemias are inherited blood disorders. They are caused by a reduction or lack of the β chains of hemoglobin and can result in severe anemia. At which stage do you predict the onset of symptoms of β thalassemia in affected patients?

Answer 25

Shortly after birth

Question 26

Bisphenol A (BPA) is a chemical used to manufacture certain types of plastic. It leads to undermethylation of DNA at certain loci in animals exposed to BPA. If a mouse is exposed to BPA, will its offspring also have undermethylation of these DNA sequences?

Answer 26

No, since this is an epigenetic event it will not be passed to the offspring.

Question 27

You are studying two proteins that play a role in cell wall formation in plants. You are interested in determining the genomic location of the gene(s) that encode these proteins. You are surprised to find that the two proteins appear to be encoded by the same gene, and that the sequence encoding one appears immediately before the other one, in frame, although they do not have overlapping sequence. Which mechanism for maximizing genetic information do you suspect is at play here?

Answer 27

Precursor protein is cut to yield two proteins

Question 28

Consider a gene with the following structure:
Exon Q - Intron 1- Exon R - Intron 2 - Exon S - Intron 3 - Exon T - Intron 4 - Exon U.
Select possible protein products that could result from this gene.

Answer 28

Q-R-S-T-U

Q-U

Q-S-T-U

Question 29

Development of the pancreas in an embryo into a dual gland that has both exocrine and endocrine functions begins when _____.

Answer 29

A transcription factor stimulates progenitor cells to give rise to exocrine or endocrine cells

Question 30

Fetal hemoglobin carries _____ percent more oxygen than adult hemoglobin.

Answer 30

20 to 30

Question 31

A treatment for some forms of anemia is to take a drug that turns on transcription of fetal hemoglobin. This would increase the proportion of_____ globin chains.

Answer 31

Gamma

Question 32

The most important chemical group that determines how tightly histones bind DNA is _____.

Answer 32

Acetyl

Question 33

You are doing a biochemical analysis of molecules from cells from patients with a certain disease compared to cells from control patients who do not have the disease. You find that patients with the disease have unusually high levels of cytosine molecules with CH3 groups attached in their cells. Which modification has taken place in the cells from the disease patients?

Answer 33

DNA methylation

Question 34

Which metaphors correctly compare chromatin remodeling and microRNA function?

Answer 34

An on/off switch and a dimmer switch

Question 35

You are studying two proteins in mouse cells. When you attempt to sequence the genes for these proteins, you are shocked to find they are found at the same location in the genome. However, the protein sequences are completely different! How do you explain this observation?

Answer 35

The genes are encoded from different strands of DNA.

Question 36

A gene is structured as follows: Exon 1 - Intron 1 - Exon 2 - Intron 2 - Exon 3 - Intron 3 - Exon 4 - Intron 4 - Exon 5. If splicing occurs at all the possible places it can, what information will the final protein contain?

Answer 36

Exon 1 - Exon 2 - Exon 3 - Exon 4 - Exon 5

Question 37

The Epstein-Barr virus causes mononucleosis, or mono. Once a person is infected with this virus, the virus can reactivate many years later, in some cases causing a recurrence of symptoms. Which of the following may account for the reactivation?

Answer 37

After initial infection, many viruses incorporate into the human genome or exist in the host nucleus as an episome that can later reactivate

Question 38

The most abundant type of DNA repeat sequence is called a _____.

Answer 38

Transposon