Gene Expression Shred Fest II LO

Question 1

what is a nucleosome?

Answer 1

octamer of 8 histone proteins with DNA wrapped around it

2 of each (H2A, H2B, H3, and H4)

Question 2

how many base pairs of DNA wrap around a histone?

Answer 2

147 bp

Question 3

which is negative and which is positive between DNA and histones?

Answer 3

DNA negative, histone positive

Question 4

what are the 2 forms of chromatin?

Answer 4

heterochromatin

euchromatin

Question 5

what is heterochromatin?

Answer 5

highly condensed chromatin that is transcriptionally inactive and sterically inaccessible

Question 6

what is euchromatin?

Answer 6

less condensed, transcripationally active, sterically accessible

Question 7

what are the 2 classes of chromatin remodeling factors?

Answer 7

DNA dependent ATPases

HATs and HDACs

Question 8

what is an example of a DNA-dependent ATPase?

Answer 8

SWI/SNF

Question 9

what is the function of SWI and SNF?

Answer 9

disrupt histone octamers and DNA to allow for previously unaccesible areas of DNA to be accessed through ATP hydrolysis

Question 10

what is the function of HATs and HDACs?

Answer 10

reversibly modify histones through acetylation

Question 11

what is a HATs?

Answer 11

histone acetyltransferases

Question 12

what is a HDACs?

Answer 12

histone deacetylases

Question 13

what is the specific function of HATs?

Answer 13

acetylate N-termini of histones thus causing neutralization of histone and releasing DNA from histone

Question 14

what is the specific function of HDACs?

Answer 14

histones retain their positive charge

Question 15

what is the histone code hypothesis?

Answer 15

lysine acetylation on histones thought to generate binding sites for protein-protein interactions which helps recruit different domains that alter chromatin structure allowing pol access to DNA

Question 16

what is the function of CREB binding protein (CBP)?

Answer 16

transcriptional coactivator for many different transcription factors, regulates cell growth and division and required for normal fetal development

Question 17

what is the cause of Reubinstein-Taybi Syndrome?

Answer 17

mutations in one copy of CREB binding protein, causes haploinsufficiency and results in widespread transcriptional changes due to lack of activation of transcription

Question 18

how is leukemia caused with regards to HATs and HDACs?

Answer 18

it is a hematopoietic malignancy, generally result of chromosomal translocations leading to gain of function fusion proteins, causes fusion of HATs and HDACs and alters the activity of these regulators

Question 19

what is haploinsufficiency?

Answer 19

person has only one functional copy of a gene and that one gene does not produce enough protein to allow for wild type phenotype

Question 20

what do transcriptional activators recruit to change chromatin?

Answer 20

HATs, activate transcription

Question 21

what do transcriptional repressors recruti to change chromatin?

Answer 21

HDAC, deactivate transcription

Question 22

what are specificity factors?

Answer 22

factors that alter the affinity of RNA polymerase and thus increase or decrease transcription levels

Question 23

how do repressors affect transcription?

Answer 23

they bind to non-coding sequences on DNA strand close to the promoter region, impedes RNA pol progress on strand

Question 24

how do activators affect the level of transcription?

Answer 24

increase attraction of RNA pol to promoter through interactions with pol directly or with structure of DNA

Question 25

how do enhancers affect the level of transcription?

Answer 25

bind to sites on DNA helix that are bound by activators to loop the DNA and bring a specific promoter to the initiation complex