Meiosis Flashcards
What is meiosis
Meiosis takes place in the sex organs and pedicels 4 non identical daughter cells with half the number of chromosomes as the parent cell-gametes haploid
Mitosis
A cell division where a parent cell is duplicated and forms two identical copies of itself with the same amount of chromosomes -somatic cells
Meiosis takes place where?
Sex organs -gonads
testes and ovaries
Describe interphase
Interphase is the phase where Dna replication occurs.Single stranded Dna become double .There is double the amount of dna for the new cells that will be formed
what is another word for meiosis
Reduction cell decision because it divides the chromosome number
Characteristics of homogolous pairs
Same shape
same size
Position of gene
Position of centromere
Gene codes for same characteristics
What forms spindle fibres and when
Centrioles metaphase 1&2
Describe Prophase 1
Chromatin network shortens then we have chromosomes
Homogolous chromosomes (paternal and maternal)
nucleolus and nuclear membrane disintegrates
Bivalent pair goes through crossing over
Genetic material is exchanged
centrioles move to poles and start forming spindle fibres
Metaphase 1
Random arrangement of homologous pairs on equator
spindle fibres connect to centromere
Anaphase 1
Spindle fibres shorten
Chromosomes are randomly pulled to different poles (random segregation)
allows for 1 allele per gene
cleavage farrow indicates beginning of cytokinesis
Telophase 1
Chromosomes assemble as opposite poles and nuclei form
cytokinesis ends
two daughter cells with different genetic material form
nuclear membrane and nucleolus form
When a chromosome does not split
Non disjunction
Non Disjunction
Failure of separation of chromosomes-anaphase 1
Failure of separation of centromere -anaphase 2
extra gamete or one less gamete
Down’s syndrome second name
Trisomy 21
Genetic variation is caused by
Crossing over in prophase 1(genetic material is exchanged and new combinations form)
Random arrangement (metaphase 1 and 2)
Random segregation
