CRISPR-Cas9

Question 1

what is CRISPR-Cas9 + what does it stand for

Answer 1

the newest gene-editing biotechnology; clustered regularly interspaced short palindromic repeats

Question 2

bacterial immune defense: when attacked by a virus… (how do they save their memory of that virus)

Answer 2

bacterial enzymes cut out segments of the viral DNA and insert them in an area of their genome called the “CRISPR region”

Question 3

true or false: bacteria make an RNA molecule based on the save viral DNA

Answer 3

true

Question 4

what do “Cas” enzymes do (2)

Answer 4

1) they compare DNA in their cytoplasm to the viral DNA code
2) If it matches, it will cut that DNA at that place

(in an infection, this effectively cuts up the viral DNA so that the lytic or lysogenic cycles cannot proceed)

Question 5

how do we use this gene for editing

Answer 5

method: CRISPR-Cas9
basically: it’s a tweak in the bacterial system, and can be applied to eukaryotic cells

how we use it: by engineering RNA molecules to target specific genes, we can tell Cas9 exactly where to cut. When the cell machinery tried to fix the cut, it ends up modifying the sequence at the same time

Question 6

how to edit a gene using CRISPR-Cas9 (5)

Answer 6

1) Design an RNA molecule called a “guide RNA” (gRNA), that matches the gene you want to change
2) Put the RNA molecule and Cas9 enzyme into the cell you want to modify
3) The Cas9 enzyme will search for a DNA sequence that matches the gRNA
4) Once it finds that sequence, it will cut the DNA there
5) The cells machinery will rush to fix the cut. In the process, it can make directed modifications like adding or removing part of a sequence, or changing one base to another
ex:
- introduce a DNA strand that has the sequence you want
- the cells machinery will use it as a template- and make the cut DNA match this template sequence

Question 7

3 uses of CRISPR-Cas9

Answer 7

1) the CRISPR-Cas9 system is a tool to create a cut at a very specific place in a DNA strand
2) It allows scientists to take one protein (Cas9) and target a very specific spot (can be any location we chose) inside or outside of a gene
3) scientists tell Cas9 where to cut (as opposing to using a restriction enzyme which can