Extended Response 2: Mutations and Gene Pools

Evolution

The gradual change in characteristics of a species.

Population

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

Allele Frequency

The frequency of allele types in a given population.

Mutations

A change in a gene or chromosome leading to new characteristics in an organism.

Types of Mutations

-          Chromosomal Somatic

-          Chromosomal Germline

-          Gene (Point) Somatic

-          Gene (Point) Germline

Malaria

A disease caused by a parasite. The parasite is spread to humans through the bites of infected mosquitoes. Causing high fever, severe chills and sweating. The malaria parasites enter that person's bloodstream and travel to the liver. When the parasites mature, they leave the liver and infect red blood cells.

Genetic Drift

The random occurrence of a characteristic in a population as a result of chance rather than natural selection.

Sickle Cell Anaemia

A group of inherited disorders that affects the shape of red blood cells, which carry oxygen to all parts of the body. Results from the inheritance of two alleles from either parent (recessive). Red blood cells are shaped like sickles or crescent moons. These sickle cells also become rigid and sticky, which can slow or block blood flow. Mutation occurs in the HBB gene that encodes beta-globin, a subunit of haemoglobin. This mutation causes haemoglobin to form abnormal haemoglobin molecules (HbS).

Tay-Sachs Disease

A genetic disorder caused by a missing enzyme that results in fatty substances accumulating in the nervous system.

Thalassaemia

An autosomal recessive genetic blood disorder characterized by reduced production of globin chains of haemoglobin, leading to anaemia. It results from mutations in genes that produce alpha-globin (HBA) or beta-globin (HBB) chains.

Gene Flow

The transfer of alleles from one population to another population through migration.

Natural Selection

The process by which a species becomes better adapted to its environment; those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations.

Founder Effect

A type of genetic drift where a new population is formed by a small number of individuals.

Speciation

The splitting of a single species into two different species.

Alpha Thalassemia

Due to a mutation in the HBA gene on chromosome 16, reducing the level of alpha globin in haemoglobin.

Beta Thalassemia

Due to a mutation in the HBB gene on chromosome 11, reducing the level of beta globin in haemoglobin.