Genetic Diversity Flashcards
What is a mutation?
Any change to one or more nucleotide bases in DNA.
What is a substitution mutation?
When a nucleotide in a DNA molecule is replaced by another that has a different base.
What is a deletion mutation?
A nucleotide is lost from the normal base sequence
Name two types of chromosome mutations.
Whole set (when something has more than two sets of chromosomes), Individual (chromosomes fail to separate during meiosis).
How many daughter cells does mitosis produce?
2 daughter cells
How many daughter cells does meiosis produce?
4 daughter cells
What happens in the first division in meiosis?
Homologous chromosomes pair up and wrap their chromatids around each other. Crossing over occurs.
What happens in the second division in meiosis?
The chromatids move apart
How does meiosis bring about genetic variation within organisms?
- Independent segregation,
- Crossing over.
What is independent segregation?
Homologous pairs line themselves up at random, so a random combination goes into each cell.
How can you determine the possible number of combinations of chromosomes for each daughter cell?
2^n where n = the number of pairs of homologous chromosomes.
Define genetic diversity
The total number of different alleles in a population.
What is a population?
A group of individuals of the same species that live in the same place and can interbreed.
Describe reproductive success and allele frequency.
Gene pool contains a variety of alleles,
Mutation occurs,
Mutation provides organism with an adaptive advantage,
More likely to obtain resources, live longer and successfully breed,
Alleles passed onto the next generation,
Over many generations allele frequency increases.
Name two different types of selection.
Directional
Stabilising
What is a polygene?
When one characteristic is influenced by more than one gene.
When does directional selection occur?
When there is a change in the environment which favours some members of a species with a specific allele.
When does stabilising selection occur?
When the environment is stable, those with phenotypes that are not advantageous are eliminated.
Name three types of adaptations.
Anatomical,
Physiological,
Behavioural.
