Bio 9 - Genetic Diversity Flashcards
What is a mutation?
Any change to the quantity to the base sequence of the DNA of an organism
What is a gene mutation?
Any change to one or more nucleotide bases, or change in the sequence of the bases, in DNA
What is substitution of bases?
The type of gene mutation in which a nucleotide in a DNA molecule is replaced by another nucleotide that has a different base
What is deletion of bases?
When a nucleotide is lost from the normal DNA sequence.
Why might a polypeptide not work if there is a deletion of bases?
The amino acid sequence of the polypeptide is entirely different so its likely not to function. Sequence of bases is read in triplets and one delayed nucleotide cases all triplet to shift to the left so they are all ready differently
What is a chromosome mutation?
Changes in the structure or number of whole chromosomes
What are the two forms of chromosome mutation?
- Changes in whole sets of chromosomes
- Changes in the number of individual chromosomes
What is a diploid number?
Cells in which the nucleus contains two sets of chromosomes
What is a haploid number?
Cells that contains only a single copy of each chromosome eg. gametes
What is crossing over?
Chromatids twist around each other and bits of chromatids swap over
When does crossing over happen?
During meiosis I
What are the two events that happen in meiosis that lead to genetic variation?
- Crossing over
- Independant segregation
What is independent segregation?
When homologous pairs are separated in meiosis I, its random which chromosome pairs up with daughter cells.
The 4 daughter cells produced have different combinations of maternal and paternal.
Mitosis or Meiosis: Produces cells with the same number of chromosomes as the parent cell
Mitosis
Mitosis or Meiosis: Produces cells with half the number of chromosomes as the parent cell
Meiosis
Mitosis or Meiosis: Daughter cells are genetically identical to each other and to the parent cell
Mitosis
Mitosis or Meiosis: Daughter cells are genetically different from one another and the parent cell
Meiosis
Mitosis or Meiosis: Produces two daughter cells
Mitosis
Mitosis or Meiosis: Produces four daughter cells
Meiosis
What is genetic diversity?
The number of different alleles of genes in a species or population
What is genetic diversity increased by?
- Mutations in the DNA
- Different alleles being introduced into a population when individual from another population migrate into them and reproduce
What do genetic bottlenecks do to genetic diversity?
Reduce it
What is a genetic bottleneck?
An event that causes a big reduction in a population
What is the founder effect?
It describes what happens when a few organisms from a population start a new colony. There are only a small number of different alleles in the initial gene pool.
