MCM LO Lecture #3

Question 1

Describe a transcript and its relationship to the gene and coding strand.

Answer 1

A transcript is an exact copy of the coding strand formed out of RNA and is the code to be translated into protein.

Question 2

Detail the action of RNA Polymerase II along with its general transcription factors.

Answer 2

RNA pol II-
TFIID-recognizes TATA induces assembly of transcription initiation complex on gene/Binds DNA with TBP subunit
TFIIB-Recognizes BRE element in promotors/posiotions RNA pol at the strat site of transcription
TFIIF-Stabalizes RNA pol interaction with TBP and TFIIB/ helps attract TFIIE and TFIIH
TFIIE-attracts and regulates TFIIH
TFIIH-unwinds DNA at the transcription starting point phosphorylates ser5 of RNA pol to CTD/Releases RNA Pol from the promotor

Question 3

Be able to explain how replication on the lagging strand is different than replication on the leading strand.

Answer 3

Replication on the lagging strand requires multiple RNA primers placed by DNA primase forming okaski fragments which then DNA ligase connects

Question 4

Describe in sequence the process of DNA replication.

Answer 4

1. DNA binding proteins from bubble at replication site uses atp
2. DNA helicase binds and continues to unwind/topoisomerase prevents supercoiling/SSB stabilize replication fork prevent it connecting back together
3. DNA primase binds and adds RNA primer
4. DNA polymerase binds and synthesizes onto the 3’ end clamp protein hold it on
5. lagging strand discontiuiosly uses Dna primase to add RNA timers creating okazaki fragments on lag strand
6. RNAse H removes RNA primers ligase connects fragments

Question 5

List and describe the post-translational modifications (capping, splicing and polyadenylation), export and degradation of the transcript.

Answer 5

Capping-5’ end protects from exonucleases/ribosomal binding/export from nucleus
Polyadenylation-same but helps with transciptional termination

Question 6

Define the multiple levels of transcriptional regulation that occur and be able to apply them.

Answer 6

Aceytlation- Promotes loosening around the histone promoting trascription og dna
deactylation causes tightening around histones
Methylation- acts to silence genes

Question 7

Diagram the process of RNA interference and be able to apply it.

Answer 7

RNA interferance-MiRNA /SiRNA Mirna is usually encoded into the gene sirna introduced sythetically