Meiosis Flashcards
Why does meiosis occur?
To produce 2 haploid cells which have varied gametes for reproduction and variation
Name the 4 causes of variation
Crossing over
Random assortment
Random gamete selection
Mutations ( gene and chromosomal )
What happens during crossing over ?
Alleles from 1 chromosome switch with alleles from another chromosome
After crossing over has occurred, what is the resultant chromatid called ?
Recombinant chromatids
The point at which the two alleles cross is called the …
Chiasma
Crossing over occurs in which phase ?
Prophase 1
What happens during Random Assortment ?
Chromosomes line up randomly at equator
Which phase(s) does Random Assortment happen ?
Metaphase 1 And 2
Explain Random Gamete Selection
No individual controls which sperm will fertilize which egg
What is a mutation?
A spontaneous change in the genetic code
Explain a gene point mutation
Error in placing of nucleotides. Addition. Substitution. Deletion. Occurs in Interphase
Explain a chromosomal mutation
Caused during meiosis in formation of gametes. Extra or missing chromosome.
What causes an extra or missing chromosomes in a chromosomal mutation?
Nondisjunction
What will Nondisjunction cause?
Aneuploidy
Define Nondisjunction
The failure of homologous chromosomes to separate properly during meiosis