Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Lecture 10 and 11
Transcription and RNA processing
| Term | Definition |
|---|---|
| Why are Genes transcribed ? | Genes are transcribed to make RNA |
| 1) mRNA = messenger RNA | - not as abundant - many different kinds - very diverse in sequence these RNAs contain or ‘encode’ genetic information to make proteins |
| tRNA = transfer RNA rRNA = ribosomal RNA | - these are very abundant in the cell - associated with ribosomes - not very diverse in sequence |
| long noncoding RNA (lncRNA) | A transcribed RNA molecule that does not possess an extended open reading frame and that does not represent a tRNA, rRNA, or miRNA. |
| Promoter | immediately upstream (5') to the start of transcription (+1 nucleotide); controls the access of RNA polymerase to the gene. when, where, and how much a gene is expressed. |
| Coding region | the portion of the gene transcribed into RNA, the protein coding region is the part that contains instructions for making a protein |
| Termination site | a region of the gene regulates cessation of transcription; at 3’ end of a gene. |
| Upstream and downstream sequences | provide additional information on when, where, and how much a gene is expressed. |
| What contains info on the when, where, and how much a gene is expressed? | the ‘upstream’ region and promoter |
| What are UTRs | sequences in mRNA transcript that do not code for protein |
| What does RNA polymerase require for RNA synthesis | a DNA template strand, NTPs and ATP |
| How many strands of DNA are transcribed into RNA | only one of two(the coding strand) |
| What is the coding strand the same as? | same as the transcript |
| What are template strands used to make? | The transcript |
| In what direction does RNA synthesis | 5' to 3' direction |
| Why does RNA polymerase follows the rules of base pairing? | to ensure that the correct base is added at each position on the new strand using the old strand as a template |
| Where does RNA polymerase form a phosphodiester? | d between the 3’OH group on the sugar of the last nucleotide on the growing RNA strand and the 5’ phosphate of the incoming nucleotide |
| Unlike DNA polymerase, what can RNA polymerase do? | start transcription without a primer |
| What are the four stages of transcription | promoter recognition, initiation, elongation, and termination |
| Eukaryotic Transcription | - takes place in the nucleus and the processed mRNA is exported to the cytoplasm for translation - require many other proteins (not sigma factors) to work with RNA polymerases (3). - Co-regulated cannot be linked and transcribed together |
| Prokaryotic Transcription | transcription and translation are coupled Prokaryotes require sigma factors for RNA polymerase (1 only) Co-regulated prokaryotic genes can be linked and transcribed together |
| How many types of RNA polymerase catalyzes transcription of all RNAs in E. coli | A single type |
| What is the bacterial RNA polymerase holoenzyme composed of? | a pentameric core enzyme that binds a sixth subunit, called the sigma (s) subunit |
| Where are consensus sequences | on the coding strand |
| Why is RNA polymerase attracted to the promoter? | Because of the consensus sequences |
| What are the most common consensus sequences in bacteria? | -10 consensus sequence, 5'-TATAAT-3' (most common) -35 consensus sequence, 5'- TTGACA-3' (most common) |
| What is the first step of bacterial transcription? | The RNA polymerase core enzyme and sigma subunit bind to the -10 and -35 promoter consensus sequences. |
| How do sigma factors affect RNA polymerase? | directs core RNA polymerase to the promoter region at the start of the gene |
| What is the second step of bacterial transcription? | DNA unwinds near the start of transcription to form the open promoter complex(about 18bp at the -10 con. SIte) |
| What is the third step of bacterial transcription? | RNA polymerase holoenzyme initiates transcription and begins RNA synthesis. The sigma unit dissociates and core enzyme continues transcription |
| What is the fourth step of bacterial transcription? | The core polymerase goes on, extending the mRNA transcript DNA unwinds in front of RNA polymerase and rewinds after it has passed |
| What is the fifth step of bacterial transcription? | When transcription of the gene is completed, the RNA falls off the core enzyme The core enzyme dissociates from the DNA Termination is triggered by termination sequences |
| What signals transcription termination in bacteria? | a DNA termination sequence that usually contains a repeating sequence |
| What happens in intrinsic termination? | a mechanism dependent only on the presence of the repeat-induced secondary structure needed for termination |
| What happens in rho-dependent termination? | requires a different termination sequence and the rho protein |
| How many RNA polymerases do Eukaryotes have | RNA polymerase I, RNA polymerase II, and RNA polymerase III |
| What does RNA polymerase I do? | synthesizes ribosomal RNA (rRNA) in the nucleolus |
| What does RNA polymerase II do? | synthesizes protein-coding messenger RNA (mRNA) |
| What does RNA polymerase III do? | synthesizes transfer RNA (tRNA) and other small RNAs in the nucleoplasm |
| What has a TAATA box? | prokaryotes |
| What has a CAAT box | Eukaryotes. |
Created by:
achrist5
Popular Biology sets