Lecture 5 - Development Genetics Flashcards
What are genes named after?
Protein product or phenotype (whichever came first)
What is italicised in nomenclature?
Species name & gene name
What is not italicised in nomenclature?
Proteins
What are examples of radiation that cause mutations?
- ultraviolet light
- x-rays
- radioactivity
What are examples of chemicals that cause mutations?
- base analogues
- base modifiers
- intercalating agents
What are different types of mutations that can occur?
- point mutations (single base-pair)
- deletion
- insertion
- translocation
What are germline mutations?
Inherited mutations (sperm or oocyte)
What are somatic mutations?
In our body
What is the name given to the production of mutations in model organisms?
Mutagenesis
Define the consequence of gene knockout?
This completely removes the gene to determine its function
Define the consequence of gene replacement (knock-in)?
Usually makes small changes to the endogenous gene
What can CRISPR be used for?
can be used to knock-out or knock-in.
What is the advantage of using CRISPR?
It works in any organisms
What are the 3 ways mutations affect genes?
- changes in regulatory sequences
- changes in non-coding sequences
- changes in the coding sequences
How can mutations affect changes in regulatory sequences?
changes DNA, that affects transcription - can lead to less protein being created
How can mutations affect changes in non-coding sequences?
Affect RNA splicing, stability or translation
How can mutations affect changes in the coding sequence?
May alter amino acid, affecting folding of the protein, or create premature stop-codon = truncated protein
What is the word to describe a mutation that a single amino acid substituted?
Missense (point) mutation
What is the word to describe a mutation that causes a stop codon?
Nonsense
What is a domain?
Functional unit in a protein
What is a dimer?
When 2 of the same protein bind together
What is a conformational change?
A change in protein structure
What is the process by which 2 copes of the same protein interact?
Dimerisation
What is an amorphic mutation (A non-functional version of protein/non-functioning)?
A missense mutation that completely inactivated the DNA binding domain.
What occurs if there is one mutation in an amorphic mutation?
Normally there’s enough gene product from one wild-type copy - Haplosufficient
What occurs if there is two mutations in an amorphic mutation?
Strong phenotype due to no transcriptional activation. This is recessive.
What is a hypomorphic/weakened mutation?
A missense mutation that weakens the DNA binding domain
What occurs if there is one mutation in a hypomorphic mutation?
There is normally enough green product from one wild-type copy. The mutant form many also diverse with the wild type and still activate transcription.
What occurs if there is two mutation in a hypomorphic mutation?
Mild phenotype due to poor transcription activation. The dimer forms on DNA but is often falling off. This is recessive.
What is an antimorphic mutation?
A missense mutation that destroys the dimerisation domain
What occurs if there is one mutation in an antimorphic mutation?
The mutant form binds DNA but doesn’t dimerise with the wild type & thus doesn’t go through a conformational change to become active.
What occurs if there is two mutation in an antimorphic mutation?
Completely inactive
What is a hypermorphic mutation?
A missense mutation that results in activation that is independent of dimerisation
What occurs if there is one mutation in a hypermorphic mutation?
The mutant form binds DNA that is active all the time. We call this CONSTITUTIVELY ACTIVE. This increases the overall activation of transcription. This is dominant.
What occurs if there is two mutations in a hypermorphic mutation?
The same - DNA active all the time
What is the difference between amorphic & antimorphic mutations?
Amorphic - recessive: 1 mutant would still allow wild-type to transcribe
Antimorphic - dominant negative: 1 mutant will poison wild-type, as it is a competitive inhibitor.
What are the 3 types of loss-of-function mutations?
- amorphic
- hypomorphic
- antimorphic
What is a type of gain-of-function mutation?
Hypermorphic
What is the name of different mutations in the same gene?
Alleles
How do you create a GFP (green fluorescent protein protein) transgenic line?
- genomic DNA with all of the regulatory elements - this may include replacing the stop codon with a GFP gene.
- genetically engineered GFP onto the end of the last exon (gene fusion) or replace the gene (reporter construct).
- Re-introduce this into the animal.
What are 2 uses of GFP transgenic lines?
- to follow expression of a gene or to follow the behaviour of cells in vivo.
- to follow sub cellular localisation of a protein
