Genetics Ch.16

PRC! can inhibit transcription in which 3 ways?

1. Chromatin compaction 2. Covalent modification of histones 3. Direct interaction with transcription factor

What are 3 common abnormalities found in cancer cells?

1. DNA methylation 2. Covalent modification of histones 3. Chromatin remodeling

What is are examples of cis- mechanisms?

1. Genomic imprinting 2. X-chromosome inactivation

What are examples of epigenetic changes during development?

1. Genomic imprinting 2. XCI 3. Formation of specific cell types (muscle cells, nerve cells)

In spermatogenesis, methylation of Igf2 occurs at which 2 sites?

1. Imprinting control region (ICR) 2. differentially methylated region (DMR)

What causes chromatin modifications to become abnormal, promoting cancer?

1. Mutation in genes that encode chromatin-modifying proteins 2. Environmental agents alter function of chromatin modifying proteins

Which 2 competing groups of protein complexes are key regulators in epigenetic change during development?

1. Trithorax Group (TrxG) 2. Polycomb Grooup (PcG)

What are examples of trans- mechanisms?

1. feedback loop 2. paramutation

tumor suppressor genes

A gene whose protein product inhibits cell division. Helps prevent cancer

Paramutable

An allele that can be altered by paramutation

Paramutagenic

An allele that can change the expression of another allele

How are specific genes or chromosomes targeted for epigenetic changes?

By transcription factors or non-coding RNAs

What 2 ways are epigenetic changes maintained?

Cis- and Trans- mechanisms

When agouti mice had darker fur, this was correlated with:

DNA methylation

_______ involves a series of genetically programmed stages where a fertilized egg becomes and embryo and eventually an adult

Development

cis-epigenetic mechanism

Epigenetic mechanism that affects gene at that site only, and does not affect the same gene located elsewhere (if gene has 2 copies within the cell)

the study of the mechanisms that lead to changes in gene expression. These changes are reversible, can be passed down, but do not change the DNA sequence itself. This defines ________

Epigenetics

In Igf2, _____ form a loop in DNA due to unmethylated ICR and DMR, where ______ do not form a loop due to methylation in ICR and DMR.

Females; males

Xist and Tsix are transcribed in ______ direction

Opposite

What are 2 types of polycomb group complexes?

PRC1 and PRC2

What are examples of environmental agents causing epigenetic changes?

Temperature, diet, toxins

Paramutagenic alleles (if less stable) can sometimes revert back to stronger alleles that are not paramutagenic: T/F?

True

DNA methylation Chromatin remodeling Covalent histone modification Localization of histone variants Feedback Loops These are all examples of:

Types of molecular change that underlies epigenetic regulation

For some plants, a prolonged cold temperature period could activate: ______ and ______

VIN3 and COLDAIR genes

vernalization

Where certain plant species must be exposed to the cold before they can flower

trans-epigenetic mechanism

an epigenetic mechanism that affects both copies of a gene within a cell. It is caused by diffusible factors (such as TF)

Paramutation

an interaction between two alleles at a single locus, where one allele induces a heritable change in the other allele.

The maize allele B' can:

can cause methylation of the other allele, B-I (i is paramutagenic)

Oncogenes

cancer causing genes

The FLC gene is repressed by:

chromatin modification, methylation by VIN3-PRC2 complex

For environmental effects, the agouti gene in mice is used to study ______ effects.

dietary

The weaker expression of a paramutagenic allele is due to:

epigenetic changes (these decrease or silence transcription)

epigenetic changes that are passed from parent to offspring

epigenetic inheritance

genomic imprinting

expression of an allele in offspring depends on whether the allele is inherited from the male or female parent

Igf2 mechanism is an example of:

genomic imprinting

A functional mop1 gene is needed for:

paramutation

In Arabidopsis, both FT and SOC1 activate genes that:

promote flower development

In Arabidopsis, FLC's role is:

represses FT and SOC1

Silencing of paramutagenic alleles may occur with:

short non-coding RNAs

Multiple tandem repeat sequences are near coding sequences of paramutagenic and paramutable alleles and may be used to make ____

siRNAs

De novo methylation occurs during:

spermatogenesis

cancer

the disease caused by an uncontrolled division of abnormal cells

For bees, a diet involving methylation will result in a _____ bee.

worker