Control of Eukaryotic Gene Expression

Question 1

Examples of gene expression regulation points

Answer 1

transcriptional control, RNA processing, translational control & protein controls

Question 2

What is the function of RNA polymerase III

Answer 2

transcribes ALL tRNA genes, rRNAs and other small RNA genes

Question 3

What is the function of RNA polymerase I

Answer 3

transcribes genes encoding ribosomal RNA genes, protein synthesis

Question 4

What is the function of RNA polymerase II

Answer 4

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

Question 5

What do house keeping genes encode

Answer 5

RNAs or proteins required for universal cell functions

Question 6

TRUE or FALSE - protein coding genes are regulated

Answer 6

FALSE

Question 7

TRUE or FALSE - protein coding genes are continually on

Answer 7

TRUE

Question 8

What are the functions of protein coding genes?

Answer 8

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

Question 9

What does in situ hybridisation reveal

Answer 9

gene transcription patterns in tissues and whole organisms

Question 10

What is the function of differentially expressed protein coding genes

Answer 10

make cells different to one another

Question 11

When are differentially expressed protein coding genes regulated

Answer 11

transcriptional level

Question 12

What do differentially expressed protein coding genes code for

Answer 12

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

Question 13

How is transcriptional control exerted?

Answer 13

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

Question 14

What does initiation of transcript synthesis require?

Answer 14

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

Question 15

Where are general transcription factors ALWAYS present

Answer 15

house keeping genes

Question 16

Where is the TATA box found

Answer 16

every Eukaryotic promoter

Question 17

What is the TATA box

Answer 17

DNA sequence found in the promoter

Question 18

What is the function of the TATA box

Answer 18

forms transcription initiation complex

Question 19

Where does the TATA box lie in relation to transcription

Answer 19

upstream, at start of the gene

Question 20

What does transcriptional activation require in vivo

Answer 20

other transcription activators, auxiliary proteins

Question 21

What is the function of Auxiliary proteins

Answer 21

stabilise transcription initiation complex, dictate gene transcription

Question 22

What does cycloidea transcription factor promote

Answer 22

bilateral symmetry

Question 23

What is Gli3 important for

Answer 23

limb patterning on AP axis

Question 24

What does loss of Gli3 lead to

Answer 24

extra digit

Question 25

What is Gli3

Answer 25

sequence specific DNA binding protein

Question 26

Competition between what regulates transcription

Answer 26

transcriptional activators and repressors for RNA polymerase

Question 27

Describe the transcriptional factor protein structure

Answer 27

modular, sequence specific DNA binding domain, regulatory domain

Question 28

What are eukaryotic transcriptional repressors

Answer 28

sequence specific DNA binding proteins

Question 29

How do transcriptional repressors work

Answer 29

mask activation surface, or direct interaction with general transcription factors

Question 30

Describe steroid hormones

Answer 30

highly specific activating ligands

Question 31

Describe steroid hormones structure

Answer 31

hydrophobic

Question 32

How do steroid hormones move through the cell membrane

Answer 32

pass directly through

Question 33

Examples of steroid hormones

Answer 33

cortisol, estradiol, testosterone, thyroxine

Question 34

What to steroid hormones bind to

Answer 34

nuclear hormone receptors

Question 35

What to cis-acting DNA enhancer elements bind to

Answer 35

tissue-specific transcription activators

Question 36

What do transcriptional repressors interfere with

Answer 36

transcription activator function

Question 37

Describe chromatin

Answer 37

organised, supercoiled nucleoprotein fibres

Question 38

Where is chromatin NOT present

Answer 38

prokaryotes

Question 39

What do structural changes to chromatin affect

Answer 39

gene transcription

Question 40

Why do structural changes to chromatin affect gene transcription

Answer 40

can restrict accessibility of transcription factors

Question 41

What is chromatin comprised of

Answer 41

nucleosomes

Question 42

What is the function of chromatin

Answer 42

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

Question 43

What do chromatin remodelling factors do

Answer 43

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

Question 44

What is the function of chromatin remodelling factors

Answer 44

facilitate transcription factor access to target genes

Question 45

What does the covalent modification of DNA require

Answer 45

enzymes

Question 46

What happens to the regions of chromatin that are covalently modified

Answer 46

flagged to direct repressors or activators to target DNA sequences

Question 47

Where does histone H1 bind

Answer 47

edge of nucleosome

Question 48

What is the function of histone H1

Answer 48

stabilises nucleosome structure, limits accessibility of genes for transcription

Question 49

What is acetylation

Answer 49

covalent modification

Question 50

Where does acetylation take place

Answer 50

lysine in N-terminals amino acids within histones

Question 51

What is the function of acetylated lysines ?

Answer 51

Act as flags to recruit chromatin remodellers to open up chromatin

Question 52

What does acetylation signal to chromatin remodellers

Answer 52

to remove histone H1

Question 53

Where does methylation occur (chromatin)

Answer 53

cytosine bases in CpG dinucleotides

Question 54

What is methylation a hallmark of?

Answer 54

transcriptionally inactive chromatin

Question 55

Where are CpG islands often found?

Answer 55

start of the gene

Question 56

What is the function of methylation of genes

Answer 56

switch genes OFF

Question 57

What does methylation act as a flag for

Answer 57

repressors

Question 58

Describe germline methylation

Answer 58

sex specific methylation, only occurs in gamete production

Question 59

What is the function of RNA splicing

Answer 59

removal of introns and ligation of exons

Question 60

What is RNA splicing important for in Drosophila

Answer 60

sex determination

Question 61

What is the 5' cap on mRNAs required for

Answer 61

translation initiation on circularised polyadenylated mRNAs

Question 62

What is polyadenylation required for

Answer 62

form circular structure

Question 63

What is the function of ferritin

Answer 63

store iron

Question 64

What is ferritin

Answer 64

protein

Question 65

What is translation of mRNA encoding ferritin regulated by

Answer 65

positively regulated by free iron concentration

Question 66

What happens to ferritin in low iron concentrations

Answer 66

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

Question 67

What happens to ferritin in high concentrations of iron

Answer 67

aconitase dissociates from ferritin mRNA and translation occurs

Question 68

What helps to package DNA

Answer 68

chromatin remodelling factors & covalent modifications

Question 69

What iron concentration inhibits binding of aconitase to ferritin mRNA

Answer 69

high iron concentrations

Question 70

What is Gli3 involved with

Answer 70

hh signalling pathway

Question 71

What is the function of Gli3

Answer 71

regulate transcription of hh genes