Transcription in prokaryotes and eukaryotes mRNA modifications -- Lecture 13

Question 1

template strand and coding strand:

1) RNA polymerase ___, unwinds the DNA strands

Answer 1

binds to the gene

Question 2

template strand and coding strand:

1) RNA polymerase binds to the gene, ___

Answer 2

unwinds the DNA strands

Question 3

template strand and coding strand:

1) ___ binds to the gene, unwinds the DNA strands

Answer 3

RNA polymerase

Question 4

template strand and coding strand:

2) RNA polymerase reads the ___ of the gene

Answer 4

template strand

Question 5

template strand and coding strand:

2) ___ reads the template strand of the gene

Answer 5

RNA polymerase

Question 6

template strand and coding strand:

3) the RNA sequence is ___ to the template strand sequence

Answer 6

complementary

Question 7

template strand and coding strand:

3) the RNA sequence is complementary to the ___

Answer 7

template strand sequence

Question 8

template strand and coding strand:

3) the ___ is complementary to the template strand sequence

Answer 8

RNA sequence

Question 9

phases of transcription:

3 phases

Answer 9

initiation

elongation

termination

Question 10

phases of transcription:

initiation (what happens)
RNA polymerase attaches to the ___ of the gene

Answer 10

attaches to the promoter

Question 11

phases of transcription:

initiation (what happens)

___ attaches to the promoter region of the gene

Answer 11

RNA polymerase

Question 12

phases of transcription:

initiation (what does it do)

Answer 12

separates the coding and template strands

Question 13

phases of transcription:

elongation (what happens)

RNA polymerase ___ the template strand to generate the RNA transcript

Answer 13

transcribes (reads)

Question 14

phases of transcription:

elongation (what happens)

RNA polymerase transcribes (reads) the ___ to generate the RNA transcript

Answer 14

template strand

Question 15

phases of transcription:

elongation (what happens)

RNA polymerase transcribes (reads) the template strand to ___

Answer 15

generate the RNA transcript

Question 16

phases of transcription:

elongation (what happens)

___ transcribes (reads) the template strand to generate the RNA transcript

Answer 16

RNA polymerase

Question 17

phases of transcription:

termination (what happens):

RNA polymerase reaches the ___ – detaches from the DNA and releases the RNA transcript

Answer 17

termination sequence

Question 18

phases of transcription:

termination (what happens):

RNA polymerase reaches the termination sequence – detaches ___ and releases the RNA transcript

Answer 18

from the DNA

Question 19

phases of transcription:

termination (what happens):

RNA polymerase reaches the termination sequence – ___ from the DNA and releases the RNA transcript

Answer 19

detaches

Question 20

phases of transcription:

termination (what happens):

RNA polymerase reaches the termination sequence – detaches from the DNA and ___ the RNA transcript

Answer 20

releases

Question 21

phases of transcription:

termination (what happens):

RNA polymerase reaches the termination sequence – detaches from the DNA and releases the ___

Answer 21

RNA transcript

Question 22

transcription in prokaryotes:

prokaryotes have 1 type of ___

Answer 22

RNA polymerase

Question 23

transcription in prokaryotes:

___ have 1 type of RNA polymerase

Answer 23

prokaryotes

Question 24

transcription in prokaryotes:

prokaryotes have ___ of RNA polymerase

Answer 24

1 type

Question 25

transcription in prokaryotes:

the RNA polymerase has ___ distinct sections

Answer 25

2

Question 26

transcription in prokaryotes:

2 distinct sections of RNA polymerase

Answer 26

sigma factor

core enzyme

Question 27

transcription in prokaryotes:

sigma factor (what does it do)

Answer 27

initiates transcription in prokaryotes

Question 28

transcription in prokaryotes:

core enzyme (what is it and what does it do)

Answer 28

2 alpha, 2 beta subunits

synthesizes the RNA

Question 29

transcription in prokaryotes:

holoenzyme (what is it)

Answer 29

core enzyme + sigma factor

Question 30

transcription in prokaryotes:

sigma factor (SF) functions:

Answer 30

SF binds to the promoter regions of genes (DNA sequence recognition)

SF separates the coding and template strands (helicase function)

SF enables the core enzyme to begin transcription

Question 31

elongation and termination:

the ___ completes transcription w/o the SF

Answer 31

core enzyme

Question 32

elongation and termination:

once transcription begins:

Answer 32

the SF dissociates from the core enzyme

the SF will then associate w/ another core enzyme and initiate the transcription of another gene

core enzyme completes transcription w/o the SF

Question 33

transcription/translation in prokaryotes:

in prokaryotes: transcription and translation are ___

Answer 33

coupled

happen at the same time and in the same place w/in cell

Question 34

transcription/translation in prokaryotes:

why are transcription and translation coupled in prokaryotes?

Answer 34

no nucleus to separate genes and ribosomes

so the mRNA is translated as soon as it’s made

multiple ribosomes translate a single mRNA

Question 35

polycistronic mRNAS:

in prokaryotes, many RNAs are __

Answer 35

polycistronic

Question 36

polycistronic mRNAS (definition)

Answer 36

mRNA that contains the coding region of more than one gene

Question 37

polycistronic mRNAS:

polycistronic mRNAs come from gene clusters called ___

Answer 37

operons

Question 38

polycistronic mRNAS:

polycistronic mRNAs come from ___ called operons

Answer 38

gene clusters

Question 39

polycistronic mRNAS:

___ contain sets of genes that work together in a biological function (genes that need to be expressed at the same time)

Answer 39

operons

Question 40

polycistronic mRNAs:

the genes in an operon are ___ and share ___

Answer 40

transcribed together

share a single promoter region and termination region

Question 41

example of polycistronic mRNA:

Answer 41

lac operon in prokaryotes

Question 42

lac operon (definition)

Answer 42

cluster of 3 genes involved in the transport and metabolism of lactose (a carb used for energy)

Question 43

transcription in eukaryotes:

are transcription/translation coupled in eukaryotes?

Answer 43

no

transcription occurs in nucleus
translation occurs in cytoplasm

Question 44

transcription in eukaryotes:

___ different RNA polymerases w/ different roles

Answer 44

3

Question 45

transcription in eukaryotes:

RNA Pol I

Answer 45

transcribes ribosomal RNA genes (rRNAs)

Question 46

transcription in eukaryotes:

RNA Pol II

Answer 46

transcribes mRNA genes

Question 47

transcription in eukaryotes:

RNA Pol III

Answer 47

transcribes transfer RNA genes (tRNA) and rRNA genes

Question 48

transcription initiation in eukaryotes:

do eukaryotic RNA polymerases have a sigma factor?

Answer 48

no

Question 49

transcription initiation in eukaryotes:

proteins called ___ attach to the promoter region and attract RNA Polymerase

Answer 49

transcription factors

Question 50

modifications to eukaryotic mRNAs:

in eukaryotes an mRNA is called a ___ until it is modified in 3 important ways

Answer 50

pre-mRNA

Question 51

modifications to eukaryotic mRNAs:

3 important ways to modify pre-mRNA into mRNA:

1)

Answer 51

a 7-methy-guanosine is added to the 5’ end of the mRNA (5’-cap) (added by capping enzyme)

protects the mRNA from degradation on the 5’ end

Question 52

modifications to eukaryotic mRNAs:

3 important ways to modify pre-mRNA into mRNA:

2)

Answer 52

addition of a poly-A tail (~200 adenines added to the 3’ end of the mRNA) (added by the enzyme poly-A polymerase)

protects the mRNA from degradation on the 3’ end

Question 53

modifications to eukaryotic mRNAs:

3 important ways to modify pre-mRNA into mRNA:

3)

Answer 53

next the mRNA will be “spliced”