Unit 2: CRISPR DNA Flashcards
1
Q
CRISPR
A
- DNA sequences in Bacteria and Archaea that contain viral sequences and are used for defence
- basis of a DNA editing technique that allows researches to modify any sequence in the genome
2
Q
What happens when a bacterium is first infected by a virus?
A
- the bacterium makes a copy of part of the viral genome and incorporates it into its own genome
3
Q
When a subsequent infection to a bacteria from the same virus occurs, what happens?
A
- the DNA copy of the viral genome in the bacterial genome is transcribed to RNA that combines with protein that have a DNA-cleaving function
- RNA serves as a guide to identify target DNA thus ending the viral threat
4
Q
What is the small section of viral DNA that is captured and inserted into the CRISPR array called?
A
- a spacer
5
Q
What is the spacer paired with?
A
- it is always paired up with a “repeat” DNA sequence that is made from the bacterial genome
6
Q
How is the CRISPR array passed onto offspring cells?
A
- it is a permanent part of the bacterial genome and can therefore be passed onto offspring cells
7
Q
What does CRISPR stand for?
A
- Clustered Regularly Interspaced Short Palindromic Repeats
8
Q
Where is the Cas9 gene located and what does it produce? (2)
A
- upstream of the CRISPR array
- the Cas9 protein
9
Q
What is pre-crRNA
A
- the RNA sequence of the entire CRISPR array
10
Q
What is crRNA?
A
- RNA that carry exactly one “repeat” and one viral “spacer” sequence
11
Q
What is the Cas9 protein/enzymes role?
A
- picks up a crRNA and tracrDNA and scans the viral DNA and own DNA for a PAM sequences that are unique to viral DNA
- if a PAM sequence is found, Cas9 opens the viral DNA and checks it against the crRNA sample it carries, if it matches it will form complementary base pairing
- once the crRNA and viral DNA are “locked in” the Cas9 cuts up the viral DNA
