Lect 25 - investigating the function of individual genes

Flashcards on Investigating Gene Function, covering topics such as natural variants, mutations, transgenesis, CRISPR-Cas9, and gene therapy.

How can we deduce the function of a gene?

By observing the phenotype of organisms with variations in that gene.

What is the value of mutants in genetic research?

They allow us to study the effects of gene variations on phenotype.

What percentage of human genes have unknown function?

Around 20% (approximately 4,000 genes).

List four genetic techniques to discover gene function.

1. Study naturally variant organisms. 2. Increase random mutation rate and select for a phenotype. 3. Insert a copied gene into another organism (transgenesis). 4. Deliberately break a gene (targeted mutation).

Define functional molecular genetics.

The process of discovering gene function through various genetic techniques.

Why are model organisms useful for making mutants?

They are easily raised in controlled environments and are easy to manipulate genetically, and share genes with humans.

Define transgenesis.

Engineering a multicellular organism by adding in 'foreign' DNA.

What are some uses of transgenic DNA?

To understand how genes work, engineer recombinant proteins (synthetic biology), or in gene therapy.

What is a transgene?

An added gene in transgenesis.

What is the goal of modern genetics in regards to mutations?

To target mutations to the DNA sequence of your choice to 'break' specific genes.

How can we work out what a gene normally does after genetically modifying it?

By examining the organism, or its offspring, after the gene has been modified.

What does CRISPR stand for?

Clustered Regularly Interspaced Short Palindromic Repeats.

What is the function of Cas9?

CRISPR associated protein 9, which makes double stranded break in DNA at target site.

How does CRISPR-Cas9 work to mutate a gene?

Cas9, guided by a short RNA, makes a double-stranded break in DNA at the target site, leading to errors during repair (InDels) that disrupt the gene. A repair template can be provided to edit the DNA sequence.

What are Indels?

Small insertions or deletions created at the target site, potentially disrupting or mutating the gene.

What are two main targets of genetic disease intervention?

Somatic (targets cells or organs, not affecting next generation) and Germline.

Give an example of somatic gene therapy.

Cystic fibrosis treatment.

Give an example of somatic gene editing with CRISPR-Cas9.

Sickle cell disease treatment.

Describe preimplantation genetic diagnosis.

IVF used to make embryos which are then tested before implantation; only healthy embryos are implanted.

Describe the 'three-parent baby' technique.

Nuclear transfer to a donor egg is used when the faulty gene is on the mitochondrial DNA.