4.3 GENETIC DIVERSITY DUE TO MEIOSIS Flashcards
What is a gene mutation?
A change in the quantity of the base sequence of DNA in an organism.
What is a substitution mutation?
A nucleotide in DNA is replaced with another one that has a different base. Only affects one codon.
What is a deletion mutation?
A nucleotide is lost/removed from the sequence. Cause a frameshift to the left and change all subsequent codons.
What is a chromosomal mutation?
A change in the structure or number of chromosomes.
What is polyploidy?
When there are more sets of chromosomes than necessary.
What is a non-disjunction mutation?
Changes to the number of chromosomes, errors in meiosis can occur where gametes have 1 more/less chromosomes.
What is meiosis?
This process of cell division produces 4 non-identical daughter cells.
Outline meiosis.
- 2 nuclear division stages (same as mitosis).
- Forms 4 haploid cells.
- Daughter cells have half the genetic information as the parent cell.
How are the daughter cells genetically different in meiosis?
- Independent segregation of homologous chromosomes.
2. Crossing over of homologous chromosomes.
What is the independent segregation of homologous chromosomes?
During metaphase 1, chromosomes are split and randomly go to either pole, this separates the homologous chromosomes and thus leads to genetic variation.
What is the crossing over of homologous chromosomes?
Homologous chromosomes cross over each other and break parts of the chromosomes off, at the chiasmata. Here they swap this genetic information and get recombined. This leads to genetic variation.
