epigenetics and gene expression

Question 1

What is one way gene expression is controlled?

Answer 1

= epigenetics

Question 2

what is epigenetics?

Answer 2

= heritable change in gene function without changing the DNA base sequence
= these changes are caused by changes in environment and inhibit transcritpion

Question 3

What are the factors and what do these factors do?

Answer 3

= diet stress toxins
= add epigenetic chemical tags to the DNA, controls gene expression in eukaryotes
=

Question 4

What is the epigenome?

Answer 4

= a single layer of chemical tags on the DNA
= impacts the shape of the DNA-histone complex, and whether DNA is tightly wounded so wont be expressed or unwound so it will be expressed
= if the dna is tightly wounded, transcriptional factors, cannot bind, therefore inhbits transcrption

Question 5

What is the methylation of dNA?

Answer 5

= increased methylation of DNA inhibits transcription
= when methyl groups are added to the DNA they attach to the cytosine base
= prevents transcriptional factors from binding as the chromatin is more tighly wound to the histone- strognger histone dna complex,
= methylation prevents a section of DNA from being transcribed
= causes dna histone complex to be tightly wound, so transcriptional factors cannot bind to dna genes are not expressed so turn off

Question 6

What happens with the acylation of histone proteins?

Answer 6

= decreased acylation, on associated histone protein inhibuts transcription,
= if acetyl groups are removed from the DNA, histones become more positive and are attracted more to the phosphate group on DNA
= makes dna and hustones more strongly associated and hard for transcirotopnal factors to bind
= acetyl grpups are negatie, so repelling the DNA- binds to histone

Question 7

What normally does acylation cause?

Answer 7

= histone acylation results in loose packing of histone dna complex, transciptioal factors can bnd and genes are expressed/turned on

Question 8

what are tumor supressor genes?

Answer 8

= these genes produce proteins to slow down cell divison and cause cell death by identifying and destorying mjutated cells.

Question 9

what happens if there is a mutation in timour supressor gene?

Answer 9

= not producing proteins to carry out function
= cell division would continue,
= mutated cells would not be identified and destoryed

Question 10

What happens with abnormal methylation?

Answer 10

= links to control of transcription- methylation causes a gene to turn off or on

Question 11

What happens if a tumor supressor gene is hypermethylated?

Answer 11

= increased number of methyl groups attached to it
= gene becomes inactivated
=turned off

Question 12

What happens if there are hypomethylation?

Answer 12

= oncogenes: genes that create a protein, triggers mitosis to occur
= reducing number of methyl groups attached, results to gene being permanently switched on