Topic 14 CRISPR Flashcards

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1
Q

What does crisper stand for
Where is it discovered
What is it used for

A

Clustered regularly interspersed palindromic repeats

Found in bacteria, was a defence system for them do develop an immune system

Edits genes in plants and animals

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2
Q

What are steps 1 and 2 in crispr in bacteria

A

Step 1: Cas1 and Cas2 complex cut out the spacer dna from the viral infection

Step 2: the spacer is incorporated into the the separate genomic crispr region

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3
Q

What are steps 3 and 4 in crispr in bacteria

A
  1. The crispr region with the spacers gets transcribed and cleaved to give guide rnas (gRNA)
  2. The gRNA connects with the cas9 protien to guide it to the corresponding infection for cleavage

This immune system gets passed on to generations

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4
Q

How is crispr done in non bacteria

A

Get the cas9 enzyme and the gRNA into our cell of interest

The gRNA tells cas9 to cut (double stranded) and a specific location

This location has to be 3 nucleotides upstream of the PAM (5’ NGG), meaning the guide has to be designed to cut 3 upstream of Pam

N means any nucleotide

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5
Q

What are the two ways of repair of the double stranded cas9 break

A

Homologous recombination (HR)
Nonhomologous recombination (NHEJ)

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6
Q

What is Homologous recombination (HR)

A

We introduce a donor dna to the cell which is used as a template to repair the double stranded break

Need sequence similarly on either side of donor dna to recognize either side of the double stranded cut

With the donor dna we Can introduce mutations restore a wt sequence, inactivate a gene, etc.

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7
Q

What is nonhomologous end joining (NHEJ)

A

We don’t add in donor dna and the dna fixes itself by adding mutations or deletions

Messy way

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8
Q

What are the ethical considerations of crispr

A

Gene editing is limited to somatic cells (tissue types), fixes blood disorders, retinal disorders

But not approved for Germline cells because those changes are heritable

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