L15 - regulation of eukaryote gene expression

Question 1

what are housekeeping genes

Answer 1

genes constitutively expressed in all cells

eg respiration genes

Question 2

why do Eukaryotes show greater regulation of genes than prokaryotes

Answer 2

• different cell types + function
• need to respond to environment
• need genes at different times eg embryo vs adult

Question 3

are there operons in eukaryotes?

Answer 3

no

all genes are regulated individually

Question 4

list the stages at which E genes can be regulated

Answer 4

1. transcription (promoters, methylation)
2. mRNA processing (splicing, 5’ capping)
3. mature mRNA regulation (stability in cytosol)
4. translation / post translational (golgi)

Question 5

where is a promoter region for a gene located?

Answer 5

upstream 5’ end

Question 6

what is found in a E promoter region

Answer 6

• core promoter sequence

- regulatory promoter sequence

Question 7

RNA pol 1+3 function

Answer 7

transcribe

• tRNA
• rRNA
• some small nRNA

Question 8

RNA pol 2 function

Answer 8

transcribes protein coding genes (and some non coding RNA)

Question 9

role of core promoter region?

Answer 9

directs DNA pol to start of T

Question 10

where is regulatory promoter region

Answer 10

upstream 5’ to the core promoter region

Question 11

role of regulatory promoter region

Answer 11

sequence is recognised by regulatory transcription factors that activate / repress T

Question 12

what can general T factors bind to

Answer 12

all promoters

Question 13

what are the names of general T factors?

Answer 13

TF2A , TF2B etc

Question 14

role of general T factors

Answer 14

• position RNA at start of transcription

- help separate DNA strands for T

Question 15

what is the name of the complex formed by T factors and promoter

Answer 15

pre - initiation complex

Question 16

what is TBP?

Answer 16

important T factor
TATA binding protein
forms part of TF2D complex

Question 17

where does TBP bind to on DNA?

Answer 17

the TATA sequence of promoter in minor groove

Question 18

explain process of pre-initiation complex formation (TBP)

Answer 18

1. TBP binds to TATA sequence on core promoter forming TF2D complex
2. this bends the DNA allowing other TFs to bind
3. RNA pol recognises the complex and binds to it in the correct place for T

Question 19

where do regulatory TFs bind and what is their function

Answer 19

bind to regulatory region

activate/repress T

Question 20

what is found in the regulatory region

Answer 20

• CAAT box

- GC box

Question 21

what binds to CAAT box of regulatory region

Answer 21

CBP

CAAT box binding protein

Question 22

what binds to GC box of regulatory region

Answer 22

SPI

Question 23

role of SPI and CBP

Answer 23

activate basal level of Tscription

Question 24

how do extra RTF’s alter transcription

Answer 24

form Tscription complexes, bind to regulatory regions upstream of GC box etc and :
-interact with pol2 /general TFs
-fold DNA
-

Question 25

how do TFs bind to DNA (general)

Answer 25

have different DNA binding domains that form different AA - base interactions with DNA

Question 26

what are enhancers?

Answer 26

sequences involved in regulating tissue/time/environmentally specific translation

Question 27

describe enhancers

Answer 27

• can be up/downstream
• can be close / far away from T start site
• 200 b.p
• contain several TF binding sites
• interact with core/reg complex
• bend DNA

Question 28

what is a mediator

Answer 28

protein complex that links upstream bound TFs (eg at enhancer) to core complex

Question 29

define cis acting sequence

Answer 29

regulate transcription of adjacent gene (same chrom)

Question 30

what binds to enhancers and what do they do?

Answer 30

regulatory proteins

interact with the core complex

Question 31

what are trans acting regulatory proteins

Answer 31

bind to target sequence on any chrom

eg RNA pol 2

Question 32

do all E genes only have 1 promoter?

Answer 32

no
some have several and so have several T start sites

can produce many transcripts from one gene

Question 33

define heterochromatic

Answer 33

non transcribed regions of DNA (inactive)

Question 34

define euchromatic

Answer 34

transcribed regions of DNA (active)