Control of Eukaryotic Gene Expression Flashcards

1
Q

Examples of gene expression regulation points

A

transcriptional control, RNA processing, translational control & protein controls

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2
Q

What is the function of RNA polymerase III

A

transcribes ALL tRNA genes, rRNAs and other small RNA genes

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3
Q

What is the function of RNA polymerase I

A

transcribes genes encoding ribosomal RNA genes, protein synthesis

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4
Q

What is the function of RNA polymerase II

A

transcribes ALL protein coding genes and some non-protein coding genes

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5
Q

What do house keeping genes encode

A

RNAs or proteins required for universal cell functions

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6
Q

TRUE or FALSE - protein coding genes are regulated

A

FALSE

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7
Q

TRUE or FALSE - protein coding genes are continually on

A

TRUE

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8
Q

What are the functions of protein coding genes?

A

Metabolic pathways, nucleic acid synthesis, protein synthesis, cell survival, DNA repair

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9
Q

What does in situ hybridisation reveal

A

gene transcription patterns in tissues and whole organisms

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10
Q

What is the function of differentially expressed protein coding genes

A

make cells different to one another

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11
Q

When are differentially expressed protein coding genes regulated

A

transcriptional level

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12
Q

What do differentially expressed protein coding genes code for

A

cell adhesion proteins, ion channels, cell surface receptors, transcription factors

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13
Q

How is transcriptional control exerted?

A

binding of trans acting factor proteins to specific cis acting DNA sequences next to gene

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14
Q

What does initiation of transcript synthesis require?

A

physical interactions between trans-acting factors, RNA polymerase & transcription factors

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15
Q

Where are general transcription factors ALWAYS present

A

house keeping genes

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16
Q

Where is the TATA box found

A

every Eukaryotic promoter

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17
Q

What is the TATA box

A

DNA sequence found in the promoter

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18
Q

What is the function of the TATA box

A

forms transcription initiation complex

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19
Q

Where does the TATA box lie in relation to transcription

A

upstream, at start of the gene

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20
Q

What does transcriptional activation require in vivo

A

other transcription activators, auxiliary proteins

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21
Q

What is the function of Auxiliary proteins

A

stabilise transcription initiation complex, dictate gene transcription

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22
Q

What does cycloidea transcription factor promote

A

bilateral symmetry

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23
Q

What is Gli3 important for

A

limb patterning on AP axis

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24
Q

What does loss of Gli3 lead to

A

extra digit

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25
Q

What is Gli3

A

sequence specific DNA binding protein

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26
Q

Competition between what regulates transcription

A

transcriptional activators and repressors for RNA polymerase

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27
Q

Describe the transcriptional factor protein structure

A

modular, sequence specific DNA binding domain, regulatory domain

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28
Q

What are eukaryotic transcriptional repressors

A

sequence specific DNA binding proteins

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29
Q

How do transcriptional repressors work

A

mask activation surface, or direct interaction with general transcription factors

30
Q

Describe steroid hormones

A

highly specific activating ligands

31
Q

Describe steroid hormones structure

A

hydrophobic

32
Q

How do steroid hormones move through the cell membrane

A

pass directly through

33
Q

Examples of steroid hormones

A

cortisol, estradiol, testosterone, thyroxine

34
Q

What to steroid hormones bind to

A

nuclear hormone receptors

35
Q

What to cis-acting DNA enhancer elements bind to

A

tissue-specific transcription activators

36
Q

What do transcriptional repressors interfere with

A

transcription activator function

37
Q

Describe chromatin

A

organised, supercoiled nucleoprotein fibres

38
Q

Where is chromatin NOT present

A

prokaryotes

39
Q

What do structural changes to chromatin affect

A

gene transcription

40
Q

Why do structural changes to chromatin affect gene transcription

A

can restrict accessibility of transcription factors

41
Q

What is chromatin comprised of

A

nucleosomes

42
Q

What is the function of chromatin

A

allow for packing of DNA, prevents transcription factors from finding binding sites

43
Q

What do chromatin remodelling factors do

A

move histones along DNA - open and close access to DNA sequences

44
Q

What is the function of chromatin remodelling factors

A

facilitate transcription factor access to target genes

45
Q

What does the covalent modification of DNA require

A

enzymes

46
Q

What happens to the regions of chromatin that are covalently modified

A

flagged to direct repressors or activators to target DNA sequences

47
Q

Where does histone H1 bind

A

edge of nucleosome

48
Q

What is the function of histone H1

A

stabilises nucleosome structure, limits accessibility of genes for transcription

49
Q

What is acetylation

A

covalent modification

50
Q

Where does acetylation take place

A

lysine in N-terminals amino acids within histones

51
Q

What is the function of acetylated lysines ?

A

Act as flags to recruit chromatin remodellers to open up chromatin

52
Q

What does acetylation signal to chromatin remodellers

A

to remove histone H1

53
Q

Where does methylation occur (chromatin)

A

cytosine bases in CpG dinucleotides

54
Q

What is methylation a hallmark of?

A

transcriptionally inactive chromatin

55
Q

Where are CpG islands often found?

A

start of the gene

56
Q

What is the function of methylation of genes

A

switch genes OFF

57
Q

What does methylation act as a flag for

A

repressors

58
Q

Describe germline methylation

A

sex specific methylation, only occurs in gamete production

59
Q

What is the function of RNA splicing

A

removal of introns and ligation of exons

60
Q

What is RNA splicing important for in Drosophila

A

sex determination

61
Q

What is the 5’ cap on mRNAs required for

A

translation initiation on circularised polyadenylated mRNAs

62
Q

What is polyadenylation required for

A

form circular structure

63
Q

What is the function of ferritin

A

store iron

64
Q

What is ferritin

A

protein

65
Q

What is translation of mRNA encoding ferritin regulated by

A

positively regulated by free iron concentration

66
Q

What happens to ferritin in low iron concentrations

A

aconitase binds tightly to ferritin and blocks translation by blocking the ribosomes

67
Q

What happens to ferritin in high concentrations of iron

A

aconitase dissociates from ferritin mRNA and translation occurs

68
Q

What helps to package DNA

A

chromatin remodelling factors & covalent modifications

69
Q

What iron concentration inhibits binding of aconitase to ferritin mRNA

A

high iron concentrations

70
Q

What is Gli3 involved with

A

hh signalling pathway

71
Q

What is the function of Gli3

A

regulate transcription of hh genes