MBG PART TWO: Lecture 4 Flashcards
What happens during reverse transcription?
Get DNA from an RNA Template
What are telomeres?
End of chromosomes
What is Telomerase?
Prevents shortening of chromosomes
What does RNA contain?
The base uracil in place of thymine
What sugar does RNA have?
A ribose sugar
What type of structure does RNA have?
A tertiary structure (tRNA’s)
When may RNA interact as functional units?
In the ribosome (quaternary structure)
Is RNA less stable than DNA?
Yes.
Why is RNA less stable than DNA?
The presence of the 2’OH group in ribose causes it to react intramolecularly with the 3’OH site resulting in phosphate bond breakage.
Why use an unstable RNA?
RNA revolved first (evolution aspects) and because RNA can form many tertiary structures allowing it to have different conformations for different functions, whereas DNA is only double stranded.
What is ncRNA?
Does not code for proteins
What is mRNA?
Messenger RNA
What is Transcription?
Synthesis of RNA from DNA templates
What are cellular RNAs synthesized from?
DNA templates
What RNA’s are transcribed in both prokaryotic and eukaryotic cells?
mRNA
rRNA
tRNA
What RNA is only produced in prokaryotes?
CRISPR RNA crRNA
What viruses can copy RNA directly from RNA?
Retroviruses
What direction is RNA synthesized in?
5’ to 3’ using the 3’ to 5’ DNA template strand.
What is RNA synthesis in regards to the DNA template strand?
Complementary and Anti-parallel
What will the RNA template strand match?
The DNA non-template strand
What can transcription utilize?
Either DNA strand as the 3’ to 5’ template, but transcription always occurs in the 5’ to 3’ direction.
What are the three components needed for transcription?
1.) DNA Template
2.) 4 Ribonuceloside Triphosphates (rNTPs)
- A, U, G, C
3.) DNA dependant RNA polymerase.
How is the 5’ to 3’ RNA molecule different from the DNA non-template strand?
The uridine in the RNA replaces thymidine
What is the DNA non-template strand known as?
DNA sense
What is RNA synthesis catalyzed by?
RNA polymerases and it always proceeds in the 5’ to 3’ direction
What subunits does a core RNA polymerase consist of?
a, B, B’, omega, sigma
Do you need primers for transcription in a prokaryotic gene?
No due to the promoter regions
What is the function of Alpha subunit?
Involved in the assembly of the tetrameric core (2 of these - a2)
What is the function of Beta?
Contains the ribonucleoside triphosphate (rNTP) binding site
What is the function of Beta Prime?
Contains the DNA template binding region
What is the function of omega?
Helps to stabilize the tetrameric (a2, B B’ ) core
What is the function of sigma?
It binds to the RNA polymerase tetrameric core and assists in the correct initiation of transcription specifically at the promoter region of the prokaryotic gene. Many type of sigma factors which allows for specificity
