CRISPR

Question 1

Genome Editing

Answer 1

Also referred to as gene editing, the insertion, removal or replacement of DNA within the genome of a living cell.

Question 2

CRISPR

Answer 2

A specialised sequence of DNA nucleotides that has two important features: nucleotide repeats and spacers

Question 3

CRISPR-Cas 9

Answer 3

An immune system in bacteria that uses CRISPR nucleotide sequences and the Cas9 DNA-cutting enzyme, that functions as a primitive adaptive immune system in bacteria

Question 4

Cas9

Answer 4

An endonuclease that cuts DNA at a specific point determined by guide RNA

Question 5

Guide RNA (gRNA)

Answer 5

A specific RNA that recognises the desired DNA sequence determined by CRISPR and directs the Cas9 enzyme there to cut DNA

Question 6

bacteriophage

Answer 6

a virus that infects bacteria

Question 7

Spacer

Answer 7

Short sequences of DNA obtained from invading bacteriophages that are added into the CRISPR sequence that allows the bacteria to recognise the same virus in the event of subsequent invasions

Question 8

PAM (Protospacer adjacent motif)

Answer 8

A sequence of nucleotides that is the binding site for cas9 that helps cas9 locate the target sequence of DNA

and plays an essential role in distinguishing self from non self

Question 9

Outline the process of gene editing using the CRISPR-Cas9 system.

Answer 9

1. A guide rna is created complementary to the target gene in the organism
2. The gRNA is attached to a cas9 endonuclease
3. This gRNA-Cas9 complex is inseted into the organism’s cells
4. gRNA guides the cas9 to the complementary DNA sequence, so cas9 cuts the DNA phosphodiester bonds, leaving blunt end fragments
5. Cas9 adds in (knock in) or deletes(Knock out) nucleotides to edit the genome as DNA break is being repaired