Unit 4 day 3 Flashcards
What is holoenzyme?
It is composed of the core polymerase and the sigma factor
What is a transcriptional unit?
It extends from a promoter sequence to a terminator sequence of the DNA molecule.
What is the promoter composed of?
It is composed of a DNA sequence to which RNA polymerase binds. It is also composed of the start site (+1).
What is start site (+1)?
It is the first base to be transcribed into RNA
When does transcription bubble occur?
During elongation during transcription
What is the transcription bubble?
It is what moves down the DNA template strand at a rate of 50 nucleotides per second.
What is the transcription bubble made of?
- RNA polymerase
- DNA template strand
- Growing RNA transcript
What is known about RNA regarding length of life?
It does not last very long.
When does transcription stop?
When the transcription bubble encounters a terminator DNA sequence which is often with a series of A-T base pairs.
In what does transcription and translation often occur at the same time?
In prokaryotes.
How do prokaryotes replicate regarding time/speed?
They replicate really quick
What can embryonic stem cells do?
They can take any shape/function
What does methyl groups do?
They silence the genes.
What does acetyl groups do?
They open the DNA up so that the genes can be seen and activated.
What is LAC operon?
It is widely used in molecular biology.
What are snRNAs do?
They are within the spliceosome recognized and remove the introns and splice the exons together to produce the final mRNA transcript.
What are required for mRNA modifications?
- Addition of 5’ cap
- Addition of 3’ poly-A tail
- Removal of non-coding sequence
What does Exon do?
They code for protein
What is alternate splicing?
It is splice exons to make several proteins from 1 gene
Regarding Translation what is initiation?
mRNA, tRNA and rRNA come together at a stop codon
Regarding translation what is elongation?
tRNAs bring AA to the ribosome to build polypeptide
Regarding translation what is termination?
Ribosome encounters a stop codon and releases polypeptide.
What does aminoacyl- tRNA Synthetases do?
It adds AA to the acceptor arm of each tRNA
What does the anticodon loop of tRNA contain?
The nucleotide sequences complementary to mRNA codons
What are the 3 binding sites of tRNA?
- A site
- P site
- E site
What is the order of the tRNA binding sites?
EPA
What are the three primary functions of ribosomes?
- Recognizing the 5’ CAP and binding to the appropriate start site.
- Decode the mRNA
- Form peptide bonds between AAs using the enzyme peptidyl transferase
