Genetics Exam 3 Study Questions

Which of the following is part of the process of X chromosome inactivation: a)Expression of Xist from both chromosomes at the start of the process b)Binding of Tsix transcripts to the X chromosome to be inactivated after the Xist transcripts binds to Xic c)Compaction of the active X chromosome into a Barr body d)Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated

Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated

True/False: Nucleosome location may be changed by a process called ATP-dependent chromatin remodeling.

True

A modification that occurs to a nuclear gene that alters gene expression, but not permanently, is called ________ inheritance.

epigenetic

True/False: Activator proteins bind to silencer sequences and repressor proteins bind to enhancer sequences.

false

True/False: Transcription factors are proteins that influence the ability of the RNA polymerase to transcribe a gene.

true

How many Barr bodies would an individual with a XXY genotype possess?

1

Epigenetic inheritance may occur at which of the following stages? a)Oogenesis b)Spermatogenesis c)Embryogenesis d)All of the answers are correct

All of the answers are correct

Which of the following are molecular mechanisms used in epigenetic gene regulation? a)DNA methylation b)Covalent histone modification c)Chromatin remodeling d)Answers A, B, and C are correct

Answers A, B, and C are correct

Which of the following is the most likely location of an insulator sequence? a)Between two genes b)Within an intron c)At the beginning of a gene d)At the end of a gene e)In the middle of a gene

Between two genes

Histone acetyltransferases are directly involved in which of the following? a)Termination of gene expression b)Movement of nucleosomes c)Insertion of variant histone proteins d)Chemical modification of histones e)Removal of histones from chromatin

Chemical modification of histones

In cancer cells one allele of the tumor suppressor gene p53 is frequently mutated so that the protein is inactive, not produced, or deleted. The other allele will usually have a normal sequence and the promoter remains intact but the gene is not expressed. Sequencing with sodium bisulfite modification of DNA can be used to detect which cytosines are methylated. If the cancer cell DNA is sequenced what would be the anticipated results?

Cytosines in or near the promoter region will be methylated

A common way of studying methylation in cells is to sequence DNA samples before and after modification with sodium bisulfite. The sodium bisulfite deaminates Cytosine residues, generating Uracil residues, therefore resulting in a change in the sequence as compared to the non-modified DNA. Sodium bisulfite does not react with 5-methylcytosine so there will be no change in the sequence of those modified bases. When tumors are sequenced to study methylation patterns and epigenetic control, what would be the best control for sequencing using this technique?

DNA from non-cancerous tissue from the same individual's organ as the cancer

CpG islands are associated with which of the following? a)Steroid hormone activity b)DNA methylation c)cAMP pathway d)Nucleosome location

DNA methylation

Which of the following statements are correct? a)Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself b)Environmental epigenetic gene regulation only occurs in reptiles and insects, while developmental epigenetic regulation occurs in all animals c)Changes in gene expression based on environmental conditions are not considered normal while developmental changes are d)Environmental epigenetic gene regulation is typically reversible while developmental epigenetic gene regulation is typically not reversible.

Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself

True/False: A heterodimer occurs when two identical transcription factors interact on a sequence of DNA.

False

True/False: A repressor protein would enhance the ability of TFIID to bind to the TATA box of the promoter.

False

True/False: Both parents usually imprint the same gene.

False

True/False: DNA methylation usually activates gene expression.

False

True/False: DNA that contains actively transcribed genes would most likely contain chromatin in the closed configuration.

False

What is the molecular mechanism for imprinting a gene?

Methylation

What general transcription factor is most often affected by regulatory transcription factors? a)TFIID b)TFIIB c)TFIIE d)TFIIF

TFIID

A particular cell contains all of the standard histones but lacks several histone variants. Which of the following MAY be true of this cell? a)The cell will express different sets of genes than other cells in the same organism. b)The cell will have an enhanced ability to chemically modify its histones. c)The cell will be completely unable to remodel its chromatin. d)The cell will not be able to divide. e)The cell will be unable to express any of its genes at all.

The cell will express different sets of genes than other cells in the same organism.

Gene methylation can be detected through the use of restriction endonucleases. Usually these are used in pairs where one enzyme will digest only unmethylated DNA in its recognition sequence while the other is insensitive to methylation. Which of the following statements is correct? a)This experimental design is able to detect most of the methylated C residues in a particular region of DNA. b)These are used in pairs since experiments have to be replicated and this one way of performing a replication of the experiment c)The experimental design is flawed since there should be a third enzyme that would serve as a positive control d)The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation.

The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation.

True/False: A promoter mutation can turn a normal gene into an oncogene

True

True/False: Covalent histone modification is sometimes involved in cell differentiation

True

True/False: Housekeeping genes are unmethylated and active in most cells.

True

True/False: Steroid hormones are an example of an effector which regulates regulatory transcription factor activity.

True

True/False: The activity of some transcription factors can be regulated by covalent modifications.

True

True/False: The red1' allele is said to be paramutagenic, because it can change the expression of another allele.

True

If a human cell has two Barr bodies then the genotype of the individual could be

XXXY