Ch. 11 - Gene Expression and Epigenetics Flashcards
Hemoglobin is a protein that the blood that binds to and transports oxygen.
True
A hemoglobin molecule is made of _____ polypeptide chain(s).
Four
In the embryo, most hemoglobin molecules consist of _____.
Two epsilon chains and two zeta chains
In the fetus, the expression of the epsilon and _____ chain(s) decreases.
Zeta
In the fetus, the expression of the _____ chain increases.
Alpha
Fetal hemoglobin consists of _____.
Two gamma chains and two alpha chains
Adult hemoglobin consists of _____.
Two alpha chains and two beta chains
Compared to adult blood, fetal blood carries _____ oxygen.
20-30% more
MicroRNAs are typically about _____ bases long.
21
MicroRNAs regulate gene expression at the level of _____.
Translation
MicroRNAs are an example of _____ RNAs.
Noncoding
The human genome contains approximately _____ distinct sequences of microRNAs.
2500
MicroRNAs regulate approximately _____ of the protein-encoding genes in the human genome.
One third
The human genome contains approximately _____ genes.
21,000
Approximately _____ mRNAs can be produced from the information in the human genome.
100,000
Approximately _____ proteins can be produced from the information in the human genome.
One million
_____ explains how one gene can specify multiple mRNAs.
Alternative splicing
Select all of the mechanisms that help to maximize gene expression.
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.
Noncoding RNAs include all types of RNA except the _____.
Messenger RNAs
A _____ is very similar in sequence to a protein-encoding gene and may be transcribed, but is not translated into protein.
Pseudogene
An RNA virus uses an enzyme called _____ to copy its genetic material into DNA.
Reverse transcriptase
A DNA sequence that can move to different locations within the genome is called a ______.
Transposon
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.
Decrease acetylation of histones
Decrease phosphorylation of histones
Increase methylation of histones
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?
Using microRNAs to fine-tune protein levels
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?
Shortly after birth
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?
No, since this is an epigenetic event it will not be passed to the offspring.
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?
Precursor protein is cut to yield two proteins
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.
Q-R-S-T-U
Q-U
Q-S-T-U
Development of the pancreas in an embryo into a dual gland that has both exocrine and endocrine functions begins when _____.
A transcription factor stimulates progenitor cells to give rise to exocrine or endocrine cells
Fetal hemoglobin carries _____ percent more oxygen than adult hemoglobin.
20 to 30
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.
Gamma
The most important chemical group that determines how tightly histones bind DNA is _____.
Acetyl
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?
DNA methylation
Which metaphors correctly compare chromatin remodeling and microRNA function?
An on/off switch and a dimmer switch
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?
The genes are encoded from different strands of DNA.
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?
Exon 1 - Exon 2 - Exon 3 - Exon 4 - Exon 5
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?
After initial infection, many viruses incorporate into the human genome or exist in the host nucleus as an episome that can later reactivate
The most abundant type of DNA repeat sequence is called a _____.
Transposon
