meiosis Flashcards
what are the cell types like produced by meiosis
genetically different
how many time does a cell divide in this
2
how many times does DNA replication occur
1
how many cells are produced
4 ( gametes)
what can be said about the amount of chromosomes in the produced 4 cells
contains half the number of chromosomes (haploid) of the original cell
what happens at fertilisation
-diploid number restored of gametes
-when gametes fuse to produce a zygote
-a eukaryotic cell from two gametes
what represents diploid number
2n
what represents haploid number
n
what happens during late interphase
-dna replication
-build up of atp
-REPLICATION OF CELL ORGANELLES
What happens during the first meiotic division
separates member of each homologous pair
what happens in second meiotic division
separates sister chromatid of each chromosome
this
what is a chromosome made from
2 identical sister chromatids
how many cells are there in the
first division . And , how many chromosomes are there in each new cell
-there are 2 cells produced
-there are 2 chromosomes in each cell
-each cell has haploid number of chromosomes
how many cells are produced during second meiotic division , and how many chromatids are in each
4 gengeticly different daughter cells produced(4 haploid cells )
-containing one membrane from each homologous pair of chromosomes
-so seperated chromasone in each cell
when can variation in meiosis occur general
in haploid cells (gametes)
how can independent segregation cause variation or genetic diversity
-during the first meiotic division
-homologous chromosomes pair together then separate so one member of each pair enteres gamete
-the separation of one pair is completely separate from the other
what will gametes [rpduced from independent segregation have
one member from each original homologous pair
when does crossing over occur
during prophase in the first division
explain crossing over
-chromatids of each homologous chromosome cross over
-exchange of alleles resulting in new combinations of alleles known as recombinants
what is chromosome non disjunction
homologous pair of chromosomes dont separate during first meiotic division
-during anaphase, one pair of chromosomes is not separated and both members of a homologous pair move to same pole of cell
-non disjunction of a single homologous pair will result in gametes with one extra chromosome than normal and gametes with one less chromosome
