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Human Molecular Genetics - Lecture Twenty Four : The Human Genome and Disease

Q: What is the definition of a mutation and which types of mutations are inherited ?

A permanent alteration in the DNA sequence Can be acquired (through environment) or inherited (from parents gametes) 1. Germline Mutations Occur in germline cells (gametes; ova and sperm) These can be inherited by the next generation 2. Somatic Mutations Occur in somatic cells (diploid cells that don’t form gametes) - These can’t be inherited by next generation

Q: What are the roles of mutations ?

Driving Force for Evolution by Natural Selection : Introduce variation If favorable: advantageous Drive evolution of a population Disease Mutations can bring on damaging/harmful phenotypes that result in a disease state No Effect Mutation in a part of the DNA that has no function (known) Outcome of Mutations? Environment→ certain environmental exposures can affect gene expression Other genes→ may affect how mutated gene is expressed

Q: Classifying mutation into Dominant vs Recessive

Humans are Diploid This means that if we have a mutation in one chromosome, we have a backup: Heterozygous Or both copies can be affected: Homozygous Dominant: Only one copy of allele required for it to be expressed Recessive: Two copies of alleles required for them to be expressed

5 important questions on Human Molecular Genetics - Lecture Twenty Four : The Human Genome and Disease

What is the definition of a mutation and which types of mutations are inherited ?

A permanent alteration in the DNA sequence
Can be acquired (through environment) or inherited (from parents gametes)

1. Germline Mutations

Occur in germline cells (gametes; ova and sperm)
These can be inherited by the next generation

2. Somatic Mutations

Occur in somatic cells (diploid cells that don’t form gametes) -
These can’t be inherited by next generation

What are the roles of mutations ?

Driving Force for Evolution by Natural Selection :

Introduce variation
If favorable: advantageous
Drive evolution of a population

Disease

Mutations can bring on damaging/harmful phenotypes that result in a disease state

No Effect

Mutation in a part of the DNA that has no function (known)

Outcome of Mutations?

Environment→ certain environmental exposures can affect gene expression
Other genes→ may affect how mutated gene is expressed

Classifying mutation into Dominant vs Recessive

Humans are Diploid

This means that if we have a mutation in one chromosome, we have a backup: Heterozygous
Or both copies can be affected: Homozygous

Dominant:

Only one copy of allele required for it to be expressed

Recessive:

Two copies of alleles required for them to be expressed

Classifying mutations into "Loss of function" vs "Gain of function"

Mutations must affect the function of a gene in order to show a phenotype
Loss of function :

Cause production of a protein that doesn’t work well, or not at all
Recessive

Gain of function :

Gene works better than normal or do something unexpected
Dominant

Describe genetic determinism in genetics and gene environment interactions

Having a disease related mutated allele doesn’t mean you will definitely get the disease
Due to the effect the environment can have on gene expression

The question on the page originate from the summary of the following study material:

CELS191

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