Gene Expression II and Gene expression III (Epigenetics)

what role does the proteasome play in regulating gene expression

the proteasome degrades proteins that have been tagged with an ubiquitin molecule

An XX Drosophila fertilized egg is homozygous mutant for sex-lethal. What effect do you predict this will have on phenotype suppose they are not lethal

it will cause development as a male even though they are chromosomally female

RNAi in biotechnology is studied in where and developed at what

in a lab and developed as a pharmaceutial agent

All of the follow are examples of how RNAi could be use in biotechnology or medicine, EXCEPT

to treat a disease characterized by a gene that is not expressed

what is epigentics

the study of heritable changes in gene expression that do not involve changes to underlying DNA sequence. A change in phenotype without a change in genotype

what is an epigenetic trait

it is a stable, mitotically and meiotically heritable phenotype that results from changes in gene expression without alteration in the DNA sequence

Environmental agents including nutrition, chemicals, and physical facts such as temperature can alter the gene expression by affecting what

the epigenetic state of the genome

Epigenetics have been implicated in what 3 things

1. progressive restriction of gene expression during development

2. Allele specific expression in gene imprinting

3. environmental genome interaction during prenatal development that affect adult phenotypes

abnormal regulation of the epigenome leads to human genetic disorders such as what 3 things

1. Prader Willi syndrome

2. Angelman Syndrome

3. Beckwith- Weidemann syndrome

the loss or alternation of other epigenetic states can result in what

cancer

Epigenetic changes can occur through what 3 major mechanisms

DNA methylation, Histone modification and chromatin remodeling, and noncoding RNA

what is reversable and can add or remove methyl groups

DNA Methylation

Histone modification and chromatin remodeling includes what

acetylation , methylation, and phoshorylation

what does Histone modification and chromatin remodeling do

alter the accessibility of genes for transcription

Addition of a methyl group -CH3 to cytosine on the 5-carbon of the cytosine nitrogenous base resulting in

5- methylcytosine

reaction catalyzed by a family of enzyme is called

DNA methytransferase (DNMTs)

the added methyl groups occupy the major groove of DNA and silence genes by

blocking the binding of transcription factors and other proteins necessary to form transcription complexes

methylation occur on

cytosine bases adjacent to guanine , CpG dincucleotides

CpG dincucleotides are clusters in regions called

CpG islands

CpG islands are located

in and near promoters sequences adjacent to genes

what are typically unmethylated and avaliable for transcription

CpG island adjacent to essential genes and cell specific genes

what is usually negatively correlated with gene activity (decrease gene expression)

DNA (CpG Island) methylation

How is methylation of DNA connected to the acetylation of histones and gene expression

when DNA is not methylated but histones are acetylated, it promotes expression of DNA

what leads to the expression of genes that are associated with the characteristics of the queen bee

Royal jell suppresses Dnmt 3 which produces phenotypic differences in the worker and queen bee

stress induces epidegenetic changes that occur prenatally or early in life can influence what

behavior

newborn rats exposed to high levels of maternal nurturing care early in life has what effect to them

glcucorticoid receptor expression is increased and the newborn rats will adapt well to stress as adults

newborn rats raised with low levels of maternal nurturing have what effect to them

low glucocorticoid receptor expression and the newborns rats did not adapt well to stress as adults

which of the following statements is the most accurate in regard to mice pups who recieve high maternal nurturing

as adults they have decrease promoter methylation.

less methylation =

gene is more open and more receptors is made leading to better stress response

DNA methylation is stably maintained through what and made by what

DNA replication, inherited by newly made DNA

after DNA replication, methylates only those CG sequences that are base paired with a CG sequence that is already methylated by the

maintenance methyltransferase

newly synthesized, not yet modified histones can be modified by the

enzymes that recognize the same modification they catalyze

the cycle of modification and recognition can restore

the parental histone modification pattern and allow inheritances of the parental chromatin structure

what is monoallelic gene expression

the phenomenon in which only one of the two alleles of a gene is actively expressed while the other allele remains silent

random inactivation of MAE genes are

scattered throughout the genome

for a few mammlian traits, the phenotype depend on

which parent passes along the alleles for those traits

what is genomic imprinting

it is caused by epigentic differences in the alleles inherited from the male and female parents

Genomic imprinting involves the silencing of certain genes depending on

which parent passes them on

most imprinted genes are on

autosomes

the expression of a gene depends on

whether it is inherited from the mother or father

imprinting is the result of the

methylation, addition of CH3 groups of cysteine nucleotides

which of the following genotypes would most likely lead to a low birth weight and a small placenta

Igf2+/Igf2- where the mutated Igf2- allele comes from the paternal source

Genomic imprinting may affect only a small fraction

of mammalian genes

most imprinted genes are

critical for embryonic development and encode growth factors or other growth regulating genes

Becjwith Weideman syndrome

caused by abnormal patterns of DNA methylation resulting in altered patterns of gene expresion- IGF2

In mammalian females, one of the two X chromomes in each cells is

randomly inactivated during embryonic development

about half of embryonic cells

randomly inactivate the maternal X chromosome adn the other half inactive the paternal X chromosome

the inactive X condenses into

a Barr body

If a female is heterozygous for a particular gene located on the X chromosomes she will be a

mosaic for that character

X chromosome inactivation occurs through the action of several genes in the

X inactivation center that encode long noncoding RNAs

the products of the genes from X chromosome inactivation that ensures that

1 X chromosome is inactive and one remains active in each female cell

what XIST

X- inactive- specific- transcript

in X activation the Xist gene on the inactive X produces what

a long noncoding RNA that coats the inactive X chromosome and suppresses transcription

what is the Epigenetic effects in monozygotic twins

phenotypic differences between genetically identially monozygous twins may results from epigenetic effects

what degree of difference would you expect to see in the DNA base sequences and epigenetic marks of monozygous twins

greater differences in epigenetic marks than DNA base sequences

what is the complete set of genetic instructions encoded in the DNA of an organism

genome

what refers to the epigenetic state of a cell

epigenome

the set of chemical modification made to DNA and histones that are present in each cell at a specific time period

what is epigenome

in epigenome during its life span, an organism has on genome but this genome can be modified in

diverse cell types at different times to produce many epigenomes