Lecture 14- transcription in eukaryotes

Question 1

Chromatin

Answer 1

Mixture of DNA and proteins that form chromosomes found in cells

Question 2

Nucleosome

Answer 2

A section of DNA wrapped around a core of histone proteins
Subunit of chromatin

Question 3

Exons

Answer 3

Coding material
Present in mRNA

Question 4

Introns

Answer 4

Non-coding
Absent in final mRNA
Transcribed from DNA into RMNA but removed before final mRNA

Question 5

RNA polymerase II function (in eukaryotes)

Answer 5

Transcribes the DNA to mRNA

Question 6

Primary transript

Answer 6

Contains the introns as well as extra sequence at 3’ end

Question 7

Polyadenylation site

Answer 7

Marks end of mRNA product

Question 8

RNA splicing

Answer 8

Removes introns
Exons are joined together

Question 9

RNA polymerase I role in transcription (in eukaryotes)

Answer 9

Transcribes rRNA

Question 10

RNA polymerase III role in transcription (in eukaryotes)

Answer 10

Transcribes tRAN, snRNA and 5SRNA

Question 11

Core promoter (eukaryotic transcription)

Answer 11

Region where transcription starts
Contains RNA initiation site

Question 12

Proximal promoter

Answer 12

Next 100-200bp upstream of core promoter

Question 13

Enhancer

Answer 13

Often many 1000s of bases upstream
Plays role in regulation transcription from the core promoter

Question 14

General transcription factors

Answer 14

Interact with DNA at the core promoter
Present in all cells and forms transcription ‘machine’ with RNA polymerase

Question 15

Activators

Answer 15

Interact with DNA at the proximal promoter and enhancer
May be tissue specific
Regulate level and timing of transcription of individual genes

Question 16

Activators

Answer 16

Work to simulate transcription by:
-make assembly of transcription complex more efficient
-unpack chromatin to allow transcription

Question 17

Roles of mRNA cap

Answer 17

-Protects the 5’ end of the mRNA from degradation and important for stability
-Interacts with transcription factors that recruit ribosomes for protein synthesis
-Interacts with the cap binding complex involved in export of mRNA from the nucleus
-May be important in splicing introns near 5’ end of mRNA

Question 18

Polyadenylation

Answer 18

The addition of poly(A) tail to an RNA transcript