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Flashcards in Case unit 4 Deck (16):
1

what types of disease models are there

humans
animals
in vitro

2

difference between cell dish and body

2D vs 3D
cell vs cell contacts
complex signals
matrix ridigity
pO2 - normix conditons

3

benefits of using mice

share a genome
mammals
small
fast breeding

4

inbred mouse strains

several inbred mouse strains exist which mimic aspects of human disease
- NOD mouse (non obese diabetic)
- Lep ob/ob
do not necessarily reflect cause of human disease

5

mutant mice

inbred
make target genes knock in/out
informed by genetic research

6

how to make a mouse

breed mice to get germline mutations

modify embronic stem cell
introduce blastocyst
inject into mother
breed chimeric offspring
screen for germlin transmission

knock outs/ knock ins

7

knock outs

often performed to determine the physiological function of a gene

8

knock ins

can introduce specific mutations

9

limitations of mouse models

strains
timing - day/night cycle effect response
gender - men increase mice stress
cage - not challenged by normal environment
mice have different physiolgy to humans

10

genetic screen

Think of a process e.g. cell division
Pick a model organism
Break every gene individually (chemical mutagen)
Does the process still work?
If not – identify the broken gene!

11

advantages of screening

Quick
Simple genetics
Cheap
Ethics free
Bias free

12

CRISPR cas9

CRISPR-Cas9 is a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence.

13

What are the to key molecules in CRIPSR

an enzyme called Cas9.

a piece of RNA called guide RNA (gRNA).

14

what does cas9 do

acts as a pair of ‘molecular scissors’ that can cut the two strands of DNA at a specific location in the genome so that bits of DNA can then be added or removed.

15

what does guide RNA do

consists of a small piece of pre-designed RNA sequence (about 20 bases long) located within a longer RNA scaffold. The scaffold part binds to DNA and the pre-designed sequence ‘guides’ Cas9 to the right part of the genome. This makes sure that the Cas9 enzyme cuts at the right point in the genome.

16

how does CRIPSR work

The guide RNA is designed to find and bind to a specific sequence in the DNA.
gRNA has RNA bases that are complementary to those of the target DNA sequence in the genome.
guide RNA will only bind to the target sequence and no other regions of the genome.
Cas9 follows the guide RNA to the same location in the DNA sequence and makes a cut across both strands of the DNA.
At this stage the cell recognises that the DNA is damaged and tries to repair it.
Scientists can use the DNA repair machinery to introduce changes to one or more genes in the genome of a cell of interest.