meiosis Flashcards
what are gonads?
sex cells (gamete) producing organs testes, ovaries
what does sexual reproduction involve?
union of 2 sex cells (gametes)
what does the gamete do to the chromosomes?
reduce the number of chromosomes by half
ensure that the zygote contains the same number as the parents
what is a zygote?
fertilized egg
how are parents’ traits genetically passed on?
homologous chromosomes- contain the same genes at the same locations but the alleles can differ, therefore the cells have 2 copies of each gene
what happens if one of each homologous pair is passed to a gamete?
the gamete will contain all the genes, but only one copy, and only half the number of chromosomes
gametes contain one homologue from each homologous pair of chromosomes
how does the gamete contain one homologue from each homologous pair of chromosomes?
meiosis
what is meiosis?
special cell division in order to produce gametes with half the number of chromosomes
2 stages: meiosis I and meiosis II
what is a haploid?
half the number of chromosomes (n)
what is a diploid?
full number of chromosomes (2n)
what is synapsis?
pairing up of homologous chromosomes during prophase I
this pair of chromosomes is called a tetrad (4 chromatids)
what is a crossover?
where two chromosomes cross non-sister chromatids during prophase I (exchange genes)
what is the point of crossover called?
chiasmata
what are the stages of meiosis I?
prophase I
metaphase I
anaphase I
telophase I
what are the stages of meiosis II?
prophase II
metaphase II
anaphase II
telophase II
