Investigating function of individual genes - 25

Question 1

Do mutations always affect phenotypes

Answer 1

No - also not always fitness

Question 2

Why do we study mutations

Answer 2

To work out what the mutated gene might so (normal role of gene is to prevent mutation)

Question 3

What genetic techniques are used to find out what a gene does (functional molecular genetics)

Answer 3

Study natural mutants
Increase rate of random mutation
Transgenesis/genetic engineering
Break a gene to see outcome

Question 4

How do you increase rate of random mutation

Answer 4

select and sequence genome (genetic screening)

Question 5

What is transgenesis/genetic engineering

Answer 5

Take the selected gene, copy it and insert into another organism

Question 6

What are model organisms

Answer 6

Organisms that can be easily raised (short life) in a controlled environment

Question 7

How can we make mutants

Answer 7

With treatment of gametes with mutagens (x-rays or chemicals). These cause random and dramatic phenotypes

Question 8

What does the DNA code being universal mean

Answer 8

DNA can be used by any organism - even synthetic DNA.

Question 9

What is transgenesis

Answer 9

Engineering a multicellular organism by adding ‘foreign’ DNA

Question 10

How do we use transgenic DNA

Answer 10

To understand how a gene works. Engineer recombinant proteins or in gene therapy approaches

Question 11

What is a pathogenic variant

Answer 11

Genetic alteration that increases an individuals likely hood to get a disease or disorder

Question 12

How can you tell if a gene variant is pathogenic

Answer 12

Examining an organism and its offspring

Damage or modify gene

Question 13

What can you use to do targeted mutations

Answer 13

CRISPR-Cas9 (evolved in bacteria for antiviral defence)

Question 14

What does CRISPR - cas9 stand for

Answer 14

Clustered Regularly Interspaced Short Palindromic repeats. Associated with protein 9

Question 15

What do you combine CRISPR-cas9 with

Answer 15

Engineered short ‘guide’ RNA that only binds to gene of interest (guides to target gene)

Question 16

How does cas9 work

Answer 16

Makes double stranded break in DNA at target site (matches RNA ‘guide’)
Enzymes try to patch cut. This creates mistakes

Question 17

Why does cas9 create mutations

Answer 17

Enzymes fixing the cut have no template and often make mistakes (deletion or substitution) and cause a mutation. (can also provide a template to edit gene)

Question 18

What are somatic mutations

Answer 18

Mutation occurs in somatic cells. Doesn’t affect next generation. Target cells or organs affected

Question 19

When are mutations passed to next generation

Answer 19

When the mutation occurs in germline cells (sex cells - eggs and sperm)

Question 20

How do we gene therapy in humans

Answer 20

Deliver DNA with functional copy into lung epithelial cells (cystic fibrosis). Extra copy makes good protein, restoring function to some cells.

Question 21

Describe the ways of germline editing

Answer 21

Pre-implantation genetic diagnosis - Takes nucleus of fertilised egg and puts it into an empty egg with healthy genes. (3 parent babies)