transcription + translation

Question 1

what enzyme carried out transcription

Answer 1

RNA polymerase

Question 2

how many RNA pol enzymes are there in prokaryotes

Answer 2

1

Question 3

how many RNA pol enzymes are there in eukaryotes

Answer 3

3

Question 4

what is the role of RNA pol I

Answer 4

makes rRNA

Question 5

what is the role of RNA pol II

Answer 5

makes mRNA, snRNAs, siRNAs, miRNAs

Question 6

what is the role of RNA pol III

Answer 6

makes tRNA, 5S rRNA, and various stable small RNAs

Question 7

what type of domain does RNA pol II possess

Answer 7

a CTD (C-terminal domain)

Question 8

describe the structure of the CTD on RNA pol II

Answer 8

made up of a 7 amino acid sequence in humans that’s repeated 52 times

Question 9

what is the role of the CTD domain on RNA pol II

Answer 9

it becomes phosphorylated during transcription initiation + is involved in capping the RNA transcript + attachment to the spliceosome for RNA splicing

Question 10

what is a gene

Answer 10

a unit of DNA that contains the information necessary to specify the synthesis of a functional product (ie protein or functional RNA)

Question 11

define transcription unit

Answer 11

each transcribed section of DNA

Question 12

how many genes are in a transcription unit in eukaryotes

Answer 12

one gene

Question 13

how many genes are in transcription units in prokaryotes

Answer 13

several genes

Question 14

what are transcription units called in prokaryotes

Answer 14

operons

Question 15

define operon

Answer 15

a segment of DNA that contains a set of adjacent structural genes that are all transcribed as one unit

Question 16

T or F: operons are present in all cell types

Answer 16

false; only prokaryotes

Question 17

T or F: prokaryotic transcription units contain introns

Answer 17

false; prokaryotes have no introns, only eukaryotes do

Question 18

describe the organization of eukaryotic genes since they aren’t together on an operon

Answer 18

genes are interspersed to different chromosomes

Question 19

T or F: transcription and translation occur all in one go in prokaryotes

Answer 19

true

Question 20

T or F: transcription and translation occur all in one go in eukaryotes

Answer 20

false; they happen independently

Question 21

what must happen to eukaryotic mRNA before it can leave the nucleus and be translated

Answer 21

must be processed to become mature mRNA

Question 22

what happens in mRNA processing

Answer 22

addition of 5’ cap, addition of poly-A tail, and intron splicing

Question 23

how does RNA know where to start transcription

Answer 23

there is a promoter, which is a specific sequence upstream of a gene that is recognized by the enzyme with the help of transcription factors

Question 24

what do transcription factors do

Answer 24

help RNA pol recognize the promoter so it can start initiation of transcription

Question 25

which way does synthesis of mRNA occur

Answer 25

3-5 on the strand, or 5-3 of the NEW strand

Question 26

which end is the start of a gene: 5' or 3'

Answer 26

5' is the start

Question 27

what helper protein is required by RNA pol in prokaryotes

Answer 27

a sigma factor

Question 28

describe the role of the sigma factor in prokaryotes

Answer 28

it binds (and is now called the RNA pol holoenzyme), and it helps pol bind tightly to the promoter

Question 29

what helper proteins are required for RNA pol in eukaryotes

Answer 29

general transcription factors: TFIIH. TFIID, TFIIB

Question 30

what is the role of the general transcription factors + what do they do in initiation

Answer 30

position RNA pol at the promoter, pull apart DNA, release RNA pol from promoter so elongation can occur

Question 31

list the four consensus sequences in eukaryotes

Answer 31

TATA, BRE, INR, and DPE

Question 32

how is the TATA box involved in transcription

Answer 32

it's 30bp upstream of the start site, and the TBP domain of TFIID recognizes it

Question 33

what is heterochromatin

Answer 33

highly condensed regions of chromosomes

Question 34

what is euchromatin

Answer 34

less condensed regions of chromosomes

Question 35

describe how chromosomes assemble in eukaryotes

Answer 35

become condensed and wrap around histones to form nucleosomes

Question 36

T or F: genes in heterochromatin are hard to transcribe

Answer 36

true; because heterochromatin is very condensed

Question 37

what extra stuff is required for DNA transcription in heterochromatin

Answer 37

activators, mediators, and chromatin-modifying enzymes

Question 38

what physical things are required for translation to occur

Answer 38

mRNA, ribosomes, tRNA, aminoacyl tRNA synthetase, and various protein factors

Question 39

what are the three stages of translation

Answer 39

initiation, elongation, termination

Question 40

what are the three steps of translation elongation

Answer 40

aminoacyl tRNA binding transpeptidation translocation