Gene/ mutations

Population

A group of organisms of the same species living together in a particular place at a particular time

Gene pool

The sum of alleles in a given population

Allele

Alternate forms of a gene

Allele Frequency

How often a gene occurs in the population

Mutations

A permanent structural alteration in DNA. DNA changes can have no effect, cause harm or occasionally beneficial.

Mutant

An organism with characteristics resulting from a mutation

Mutagens agent

An environmental agent that increases rate at which mutations occur.

Examples of Mutagenic agents

• Formaldehyde

• Sulfur Dioxide

• Antibiotics

• Radiations

Gene Mutations

Change in single gene occurs. The protein that is made by the gene no longer functions as it should or is not made.

Chromosomal mutation

All parts of chromosomes is changed or missing

Induced mutation

Caused by a mutagen (UV)

Spontaneous mutation

Errors during cell division (mitosis/meiosis)

Somatic mutation (somatic cells)

A DNA change that occurs in body cells, other than egg and sperm (germ cells), they cannot be passed to offspring. E.g Skin cancer

Germline mutation (germline cells)

A DNA change that occurs in the egg or sperm. Can be passed on to offspring. (phenylketonuria PKU)

Point mutations

Occurs when 1 nucleotide is changed; only one base is changes.

Missense

Change in amino acid altering the protein

Nonsense

Change base sequence to Stop codon. Shorter protein is produced

Neutral

Harmless change in amino acid

Silent

No change in amino acid

inserted

A new nucleotide is added to the DNA strand.

Substituted

An existing nucleotide is replaced with another one, with a different base

Deleted

A nucleotide is removed from the DNA strand

Frameshift

Occurs when bases have been added or removed

Duplication

a section of chromosome occurs twice

Deletion

A piece of DNA is removed

Inversion

Breaks occur in a chromosome and the broken piece joins back in, but the wrong way around

Translocation

Part of a chromosome breaks off and is rejoined to the wrong chromosome

Non-disjunction

During meiosis, A chromosome pair does not separate and so one daughter cell has an extra chromosome and one daughter cell has one less than the normal number.

Aneuploidy

A change in the chromosomal numbers