Investigating function of individual genes - 25 Flashcards
Do mutations always affect phenotypes
No - also not always fitness
Why do we study mutations
To work out what the mutated gene might so (normal role of gene is to prevent mutation)
What genetic techniques are used to find out what a gene does (functional molecular genetics)
Study natural mutants
Increase rate of random mutation
Transgenesis/genetic engineering
Break a gene to see outcome
How do you increase rate of random mutation
select and sequence genome (genetic screening)
What is transgenesis/genetic engineering
Take the selected gene, copy it and insert into another organism
What are model organisms
Organisms that can be easily raised (short life) in a controlled environment
How can we make mutants
With treatment of gametes with mutagens (x-rays or chemicals). These cause random and dramatic phenotypes
What does the DNA code being universal mean
DNA can be used by any organism - even synthetic DNA.
What is transgenesis
Engineering a multicellular organism by adding ‘foreign’ DNA
How do we use transgenic DNA
To understand how a gene works. Engineer recombinant proteins or in gene therapy approaches
What is a pathogenic variant
Genetic alteration that increases an individuals likely hood to get a disease or disorder
How can you tell if a gene variant is pathogenic
Examining an organism and its offspring
Damage or modify gene
What can you use to do targeted mutations
CRISPR-Cas9 (evolved in bacteria for antiviral defence)
What does CRISPR - cas9 stand for
Clustered Regularly Interspaced Short Palindromic repeats. Associated with protein 9
What do you combine CRISPR-cas9 with
Engineered short ‘guide’ RNA that only binds to gene of interest (guides to target gene)
How does cas9 work
Makes double stranded break in DNA at target site (matches RNA ‘guide’)
Enzymes try to patch cut. This creates mistakes
Why does cas9 create mutations
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)
What are somatic mutations
Mutation occurs in somatic cells. Doesn’t affect next generation. Target cells or organs affected
When are mutations passed to next generation
When the mutation occurs in germline cells (sex cells - eggs and sperm)
How do we gene therapy in humans
Deliver DNA with functional copy into lung epithelial cells (cystic fibrosis). Extra copy makes good protein, restoring function to some cells.
Describe the ways of germline editing
Pre-implantation genetic diagnosis - Takes nucleus of fertilised egg and puts it into an empty egg with healthy genes. (3 parent babies)
