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Bio 311 Polvi > Topic 11 Eukaryotic Gene Regulation > Flashcards

Topic 11 Eukaryotic Gene Regulation Flashcards

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1
Q

How is transcription is eukaryotes diff from in prokaryotes

A

Eukaryote:

More genes spaced further apart (more noncoding genes)

Have 3 rna polymerases (prokaryotes have 1)
Pol1: rRNA
Pol2 mRNA
Pol3 tRNA

Transcription happens in nucleus

DNA is packaged into chromatin

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2
Q

How is transcription initiated in eukaryotes

A

General transcription factors bind to sequences in the promoter

Then RNA pol 2 gets positioned at +1 site

This all makes the PIC (preinitiation complex where the c-terminal domain (CTD) of rna pol 2 is phosphoylated by TFllH

This phosphorylation makes a binding site for enzymes to make the 5’ M7G cap in the premrna

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3
Q

What is the m7G cap

A

A methylate guanine nucleotide that’s added to the 5’ end on the mRNA

Protects mRNA from decay from exonucleases

Helps in splicing and translation

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4
Q

What is the polyA tail

A

Sequences in The 3’ UTR of mRNA signal for rna pol to be cleaved off, and then for the poly A tail to be added the 3’ mRNA end

Addition of 50-250 adenosines the protects mRNA from decay and helps in translation

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5
Q

What does splicing of introns do

A

The 5’ GU and 3’ AG in the intron are recognized by spliceosome

Diff cuting of introns make mutiple diff mature mRNAs which can make many diff protiens

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6
Q

In mature mRNA what is in each region:

M7g cap
5’ UTR
Start codon
Coding region
Stop codon
3’UTR
POLy a signal
Poly a tail

A

Protections from exonucleases, help recruit ribosomes
Landing site for ribosomes (Kozack sequence)
First translated codon methionine
Translated to amino acid sequence
Terminated translation
Protection/regulatory functions
Processing sequence for poly a tail
Protects and exports mRNA

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7
Q

What are transcription factors

What are regulators

A

Directly bind to dna

Don’t directly bind to dna

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8
Q

What are coacticators and coreoressors

A

Corefulators that activate transcription

Corefulators that repress transcription

Transcription factors can be both activators and repressor

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9
Q

What is the core promoter

What is the enhancer

A

The region surrounding the transcription start site, where the general transcription factors bind

Thousands of base pairs upstream or downstream of transcription start site. It loops to get closer to the promoter to enhance/turn on transcription

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10
Q

What do coregulators do in terms of the enhancer and promoter

A

They bring the enhancer closer to the promoter to help promotes transcription

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11
Q

What can tfllD act as

A

Both transcription factor and coactivator

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12
Q

What are the 4 domains of transcription factors , which are required, what do each do

A

DNA binding domain: required
Dimerization domain: optional, homo (same 2 proteins interacting) hetero (diff 2 proteins) dimers
Ligand binding domain: optional, hormone or vitamin, allosteric site changes conformation of the transcription factor
Activation/repression domain: required

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13
Q

What enzymes are involved in import and metabolism of glucose in the GAL system

What chromsome is each on

A

GAL1, GAL7, GAL10 : chromsome 2

Gal2: chromosome 12

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14
Q

What are the regulatory protiens in the gal system

A

GAL4 GAL3 GAL80

Regulate transcription of the enzyme encoding genes

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15
Q

What happens in the gal system when there’s is no galactose?

A

Enzyme encoding genes are not expressed because nothing to break down and import

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16
Q

What happens in the gal system when there’s is galactose?

A

Enzyme encoding genes are expressed because stuff to break down and import is here

17
Q

What is gal 4 and what does it do

A

It’s a transcription factor (binds to dna)

binds to the upstream activation sequence (UAS) of GAL7,10,1,2 in the dna to activate transcription.

Made up of activation domain, dimerization domain, DNA binding domain

Always expressed

18
Q

What are gal 3 and gal 80

A

Gal 80 is a repressor of gal 4 (stops activation of transcription)

Gal 3 in the presence of galactose undergoes a conformational change then Binds to gal80 to stop it from inhibiting gal 4 (transcription can start)

Gal 3 and gal 80 are always on

19
Q

What are histone octamers

A

Have 8 total proteins, two each of H2A, H2B, H3, and H4

Positively charged

Have a folded core and tails that intact with adjacent nucleosomes and other proteins

20
Q

What is heterochromatin

A

More compact

Constitutive heterochromatin: dna that’s always compact, regions aren’t transcribed

Facultative heterochromatin: either compact or non compact

21
Q

What is euchromatin

A

Less compact

Transcriptionally active (is being transcribed)

22
Q

What is included in chromatin modification

A

Histone modification
DNA modification

23
Q

How are histones modified and what is histone acetylation

A

Modified in the histone tails, adding an acetyl group to a lysine amino acid on the tail

24
Q

What are the two affects of acetylation

A

Reducing chromatin compaction by loosening the interaction between histone and dna

Creates a binding site for the bromodomain which is found in transcriptional activatiors (turns on genes)

Bromodomain binds to acetyl group on the histone tail

25
Q

Is a bromodomain a dna binding domain

A

No, coregulator

26
Q

What is HAT
HDAC
HMT
HDM

A

histone acetyl transferase (adds acetyl to tail
histone deacetylase (removes acetyl)
Histone methyl transferase (adds methyl
Histone demethylase (removes methyl)

27
Q

What is the histone code hypothesis

A

Different combos of histone modifications specify different transcription outcome

28
Q

Do promoter and enhancers get transcribed

A

No

29
Q

What is DNMT

A

DNA methyltransfease

It recognizes a CpG (CG) site in dna and adds methyl to it

30
Q

What are CpG islands? When are they methylate and unmethylated

Where are they found

A

CpG islands are clusters of unmethylated CpGs

They are unmethylated in expressed genes (actively transcribed)
Methylated in unexpressed genes

They are found in promoter, intragenic (in gene) and intergenic (out gene)

31
Q

Unmethylated CpG island are…..
Methylated are ….

A

Euchromatin and active transcription
Closed chromatin and repressed transcription

32
Q

What type of inheritance are dna methylation and histone modifications accosiated with

A

Epigenetic (on top of, influenced phenotype not dna sequence)

33
Q

What does parent of origin maternally imprinted mean

A

Means the copy of the gene derived from the mother is silenced, not expressed, it is methylated

This is an epigenetic mechanism where and identical gene is inactive or active depending on if it was derived from mother or father

Bio 311 Polvi (9 decks)

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