Gene Regulation Flashcards
Gene expression
Cellular function
Which cell to be expressed?
- necessary proteins must be synthesised at the proper time and place
- all cells must regulate the synthesis of proteins from their DNA
- Turn on a gene = gene expression
- The regulation of gene expression conserves energy and space
turn on genes when required
more efficent
Turn on a gene
gene expression
Process or gene expression
1) take DNA from nucleus
2) double helix
3) unwind double helix - DNA polymerase
4) give RNA»_space; protein
What to consider - importance
- What cell?
- Which chromosomes?
- What part of DNA?
- What protein?
- How much protein?
- For how long?
- Where’s it going?
Everything starts with a _____ in cell biology.
SIGNAL
Cytoplasm: the process of DNA to degrated protein:
- Chromatin
- DNA
- RNA
- mRNA in nucleus
- mRNA in nucleus
6.mRNA in cytoplasm - Polypeptide (degradation of mRNA)
- Active protein
- Degradated protein
Define Epigenetics
process of turning genes off or on
Scilencing / supresing gene
gene NOT in action
Activation of gene
gene is turned on
histones
4 stacks of 2 - DNA tightly round the histones
all histones come together to form chromosomes
Gene cannot be expressed
Histone is bound too tightly to be READ by DNA polymerase
Unwind the gene
in results of +ive/-ive charges
enough unwinding for DNA polymerase to read to gene
Acetyl group bound to histone
Decrease attraction - DNA unwinds
ACETYLATION : When DNA unwinds
Open access - gene expression
DE-ACETYLATION : DNA tightly wound
Repression - DNA is locked tight
CANNOT be read
NO ACCESS to gene expression
Histone METHYLATION
The addition of a methyl group to a DNA strand
Low attraction unwind
Gene expression therefore DNA polymerase can get in to read codon
(can have) More than 1 methyl group
HYPERMETHYLATED (e.g 3 methyl groups on one histone)
Hypermethylated - traffic jammed
Cannot be read - no expression
More than 2 methyl groups:
CANNOT be expressed because there is no room for DNA polymerase to read it
Factors that effects epigenetics
DIET
Gene regulation - 3 stages
1) Transcriptional
2) Post-transcriptional
3) Translational
Methylation of DNA (NOT histones)
Adenin binds with…
Thymin
Guanine binds with…
Cytocines
DNA CAN be methylated:
No room for transcription factors - No gene expression
Transcription factors examples
1) insulin
2) Testosterone
3) Oestrogen
What are epigenetic mechanisms accected by
- Development (in utero, childhood)
- Environmental chemicals
- Drugs/ Pharmaceutics
- Aging
- Diet
Histone modification
The binding of epigenetic factors to histone “tails” alters the extent to which DNA is wrapped around histones the availability of genes in the DNA to be activated
Chemical modification of chromatin… via histones
> Acetylation
De-Acetylation
Methylation
Chemical modification of chromatic
> Methylation (only)
What determines your eye colour
Alelles (from mother and father)
Process of choosing eye colour e.g.
- Transcription factor comes into contact / sits on enhancer
- Has an activator binds to the transcription factor to form a complex
- Stimulates histone acetylation
Promotor region
- transcription factor stimulates the promoter region to initiate DNA helices for transcription
Signal gene to stop expression
> Same eye colour
same gene
but now = Silencer
REPRESSOR binds to the silencer
What follows after transcription:
Process of producing RNA
Exones/ Intrones
Every other
Splicosomes
RNA - Process of splicing
Splice the introns = left with ONLY the exons
Exonucleases
Formation of mRNA
How many A attached
ATLEAST 250 adenine
How many times can mRNA translate
Try to make as much proteins as we can
Formation of mRNA
- Addition of 7 methyl guanine on 5’ and the polytail on 3’
- prevents exonuclease from digesting
RNA editing (1)
adenosine»_space;> inosine
RNA editing (2)
Cytosine»_space;> Uracil
translational regulation
Creating peptides
Steps
- Initiation
- Elongation
- Termination (stop codon)
Phenotype - Genetics
- DNA sequence variations
= Gene regulation
Phenotype - Enviroment
- Epigenetic modifications
= Gene regulation
Are epigenetic changes heritable?
YES
Mechanisms unknown
Define Pharmecogenomics:
” The branch of genetics concerned with the way in which an individual’s genetic attributes affect the likely response to therapeutic drugs.”
Rapid metaoliser
Functional alleles
Poor metaolizer
Non-functional alleles
Ultra rapid metaolisers
A lot of enzymes to break down…e.g codeine, morphine
Codeine - 2007 announced he max amount of drug to be taken when pregnant
Mother was found in 2006 with high levels on codeine in breast milk
Single polytide changes
affected gene
Epigenome
= genotype but all of the chemical regulation
considering - setletion and methylation
