RNA Synthesis - Transcription Flashcards
To rewrite in the same language.
Transcription - DNA->RNA
Where does transcription take place?
In the nuclear envelope.
Sequence of transcription?
DNA-PreMRNA-MRNA-RIBOSOME-POLYPEPTIDE
Where does translation take place?
Rough Endoplasmic Reticulum
Where does the process take place in bacteria?
All in the cytoplasm
Rna is a:
Polymer of nucleotides
How is it related to DNA?
Structurally - Ribose not Deoxyribose (OH on 2’C)
What is the main difference in makeup between RNA and DNA?
RNA Does NOT contain Thymine.
What is used in place of thymine?
Uracil - similar, without methyl group
What does Uracil pair with then?
UA - Uracil Adenine
GC - Guanine Cytosine
What are the products of RNA synthesis known as?
Transcripts
rRNA?
rRNA - ribosomal - catalyze reaction
tRNA?
Transfer - carry amino acids
mRNA?
Message/Messenger RNA - carries information from the gene
The template for RNA?
DNA!
The template is read to make..
Pre-mRNA
Immature Pre-mRNA then leaves…
Leaves the nucleus to be transcribed
The first phase on transcription?
Initiation
A promoter (the starter) includes:
TATA Box (Encoding Sequence)
Strands run
5-3
3-5
Just past TATA…
Encoding sequence
If these are missing the process can’t begin.
Transcription Factors
Transcription factors….
Bind TATA Box & Promotor
When the right transcription factor is present in the right __________ the process can start.
Combination! Like a keypad. Spy games.
This enzyme binds to & docks to the TF and unwinds the double helix.
RNA Polymerase
RNA polymerase adds ________ to the growing RNA strand.
Ribonucleotides
RNA Polymerase adds from the __ end.
3’
T/F Topoisomerase is present in RNA transcription.
FALSE - small thin bubble with no pressure!
Once the RNA is done synthesizing the 2 DNA strands will..
Reanneal
We now have 2 identical strands except __ instead of __
U instead of T
When does it stop?
When it hits the termination sequence! mRNA will be released
Is the pre-RNA strand ready to go?
No. Needs a 5’ cap, and a 3’ poly-a Tail
The 5’ Cap is composed of:
Methylated GTP (Backwards! G-P-P-P)
What is the purpose of the 5’ end?
Protects from degradation & facilitates binding
Why does the 5’ end facilitate binding?
Ribosomes will recognize 5’ end and bind to them
The 3’ Poly-A Tail adds:
50-200 Adenine Nucleotides
The more A’s on the end…
The longer the life!
Now capped’n’tailed are they ready to go?
NO! Still not ready to leave nucleus!
These exist as interfering RNA which have gotten in the way & have to be removed.
Introns
These are useful segments which need to be kept!
Exons
What will happen to introns?
Enzyme will cut & reattach (SPLICING)
Once capped, tailed, introns removed we have:
Mature mRNA Which can leave!! Can be transported into cytoplasm.
