9.2 meiosis and genetic variation Flashcards
what does meiosis produce?
daughter cells that are genetically different from each other
role of independent segregation of homologous chromosomes
- genetic variation;
- (Allows) different combinations of maternal and paternal chromosomes
- (To produce) haploid cells
- Allows homologous chromosomes to arrange randomly at equator
role of crossing over of homologous chromosomes
- genetic variation
- allow different combination of maternal and paternal alleles
- equivalent portions of chromatids are exchanged at chiasmata
what separates in meiosis 1?
homologous chromosomes
what separates in meiosis 2?
sister chromatids
2 ways meiosis increases variation
- crossing over
- independent segregation
what happens in crossing over
- chromatids twist around one another creating tension
- portion exchanged
- creates new combinations of maternal and paternal alleles
gene definition
length of DNA that codes for a polypeptide
locus definition
position of a gene on a chromosome or DNA
allele definition
different forms of the same gene
homologous chromosomes definition
pair of chromosomes, one maternal and one paternal, that have the same gene loci
how do you find the possible different chromosome combinations through meiosis?
2^n where n= the number of homologous chromosomes
how do you find the possible different chromosome combination through meiosis and random fertilisation?
(2^n)^2 where n= the number of homologous chromosomes
what are the 2^n and (2^n)^2 assume?
no crossing over
