Mutation

Evolution

The change in characteristics of a species over time. reflects in the change in allele frequency in a population.⁣

Gene pool

The sum all alleles in a given population⁣

Population

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

What classifies something as the same species?

able to reproduce

Mutation

A change in DNA resulting in the formation of a new allele

Gene mutations

Changes in a single gene

Point mutation

Occures in a single nucleotide; only one base changes

Types of point mutations

Insertion/Addition

Substitution

Deletion

Insertion / Addition Point Mutation

Insertion/Addition: new nucleotide being added to the DNA strand

—> Frame Shift

Substetution Point Mutation

One nucleotide is replaced by another.

Deletion Point Mutation

A nucleotide is removed from the DNA strand.

—> Frame Shift

Frame Shift

Occurs when bases have been added or removed —> the codon for an amino acid stars at a different base —>the

Chromosomal/ Block mutation

Changes in all or part of a chromosome

Types of Chromosomal/Block Mutations

Duplication

Deletion

Inversion

Insertion

Translocation

Nondisjunction

Duplication Chromosomal/Block Mutations

A section of the chromosome occurs twice.⁣

Deletion Chromosomal/Block Mutations

A piece of the DNA is removed.

Inversion

After breakage, the segment reattached in the reverse direction.

Insertion Chromosomal/Block Mutations

After breakage the part of a a chromosome reattached to the wrong chromosome.⁣

Translocation Chromosomal/Block Mutations

2 chromosomes swap DNA segments. (insertion but 2 ways)

Non-disjunction Chromosomal/Block Mutations

During meiosis a chromosome does not separate, resulting in one daughter cell having an extra or one less chromosome.

Types of mutagens

Induced Mutagens: chemical, physical, biological

Spontaneous mutagens: Errors in DNA replication, errors in cell division

Examples of C mutages

Mustard gass: Guanine replaces all other bases

Examples of P mutages

Radiation (X-rays, UV light): distorts double helix structure

Examples of B mutages

Bacteria or viruses

Somatic mutations

Occurs in somatic cells, and can not be transferred to offspring offspring.

Germline mutations

Occurs in gametes, can be passed to subsequent generations.⁣

• The individual to whom the mutation occurs is usually not affected.

4 effedcts of mutations

Missense: change in the amino acid, then protein

Nonsense: change the base sequence to the stop codon—> shorter protein—> cant carry out full function.

Neutral: change in the amino acid, but the new one is of the same type, —> little change in the protein

Silent: no change

Example of a Gene mutation

Duchenne Muscular Dystrophy (DMD)

Cystic Fibrosis

Tay-Sachs

Sickle Cell

Thalassemia

Duchenne Muscular Dystrophy (DMD)

progressive muscle wasting—→ less function

• Frameshift: due to deletion

• Spontaneous mutation

death from respiratory muscle falior

Cystic Fibrosis

Increased mucus production causes blockages in the lungs and digestive system.

• Inherited disorder

• Recessive

• Affecting chloride channels. (water follows chloride—→ no water movement across the membrane)

Tay-Sachs

Mutation in the HEX-A gene that codes for the enzyme that breaks down GM2 ganglioside (toxic) in the nervous system

—→ build up of fats =Destroys nerves

• autosomal recessive

Symptoms: mental and physical disability

*Heterozygous advantage: resistant to tuberculosis

Sickle Cell

A genetic disorder caused by a mutation in the HBB gene, leading to abnormal hemoglobin (hemoglobin S)

—→ causes red blood cells to assume a sickle shape, resulting in blockages in blood flow

Symptoms: Fatigue, Shortenss of breath

*Heterozygous advantage: resistance to malaria

Thalassemia

Effects alpha and Beta haemoglobin chains

—→ fewer functional RBC

Symptoms: Iron deficiency, Slow growth rate

Examples of chromosomal mutation

Trisomy 21

Trisomy 21

3 copies of chromosome 21

—→ Down Syndrome