Genetics Take Home Exam 3

CpG islands are associated with which of the following?

DNA methylation

Nucleosome location may be changed by a process called ATP-dependent chromatin remodeling.

True

The activity of some transcription factors can be regulated by covalent modifications.

True

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

1

Which of the following is the most likely location of an insulator sequence?

Between 2 genes

Which of the following is part of the process of X chromosome inactivation

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

Histone acetyltransferases are directly involved in which of the following?

Chemical modification of histones

Which of the following are molecular mechanisms used in epigenetic gene regulation?

Chromatin remodeling Covalent histone modification DNA methylation

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

Epigenetic inheritance may occur at which of the following stages?

Embryogenesis Spermatogenesis Oogenesis

Which statement is true? Environmental epigenetic gene regulation is typically reversible while developmental epigenetic gene regulation is typically not reversible. Environmental epigenetic gene regulation only occurs in reptiles and insects, while developmental epigenetic regulation occurs in all animals 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 Changes in gene expression based on environmental conditions are not considered normal while developmental changes are

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

A heterodimer occurs when two identical transcription factors interact on a sequence of DNA.

False

A repressor protein would enhance the ability of TFIID to bind to the TATA box of the promoter.

False

Activator proteins bind to silencer sequences and repressor proteins bind to enhancer sequences.

False

Both parents usually imprint the same gene.

False

DNA methylation usually activates gene expression.

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?

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?

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?

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.

3 facts from classmates

The presence of testosterone is correlated the production of physical aggression in males. Along with that neuroplasticity is essentially the basis of why we are able to learn, have a memory, and such. It's why there are experiences that mark our nervous system and changes our future behaviors. It's the reason why we learn to adapt to our environment over time. Even though our basic blueprint of our brain is developed in the early parts of our embryonic development, a lot of what truly becomes concrete is through these experiences in life. Essentially, it correlates to what was talked about within the TED talk of how experiences can not only change the shape of our DNA, but our brain as well. ---Tallya there are larger neuropil volumes per neuron in the female group and there is a higher neuronal density in the male group. Neuropil defines the space between neuronal and glial cell bodies which consists of dendrites, axons, synapses, etc. I found this interesting because I never would have thought that there would be a scientific difference between the brain of a female and the brain of a male. ----Sierra It is suggested that the differentiation between male and female brains depend on epigenetic modifications within the chromatin structure. The study suggested that there is not a concrete set idea of the difference in development but rather there are epigenetic mechanisms underlying that will cause variations in the brain region, where epigenetic modification controls gene expression. ----Lahra

A promoter mutation can turn a normal gene into an oncogene

True

Covalent histone modification is sometimes involved in cell differentiation

True

Housekeeping genes are unmethylated and active in most cells.

True

Steroid hormones are an example of an effector which regulates regulatory transcription factor activity.

True

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

True

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

True

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

XXXY

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

epigenetic