Meiosis Notes
Cell division that takes place in the reproductive organs to produce
gametes.
# of chromosome is reduced from 2n in parent cell to n in each
daughter cell
produces 4 daughter cells all different from one another + parent cell
Gametes formed = haploid
In sexual reproduction a male haploid gamete fuses with a female
during fertilization to form a diploid zygote
Mitosis Meiosis
2 identical daughter cells 4 un-identical daughter cells
1 division 2 divisions
For repair and growth Forms haploids for reproduction
Chromosome – long thread like structure that forms part of the chromatin network
(made up of DNA and histones)
- Linear in humans
Haploid number is same as
- 46 in somatic cells (normal cells) (2n – Diploid)
Bivalent number
- 23 in sex cells (n - Haploid)
Eukaryotes – found in nucleus
Prokaryotes – found in cytoplasm (nucleoid)
Karyotypes – map of organisms chromosomes
- 22 autosomes
- 1 sex chromosome
Homologous pairs – for each paternal chromosome is there a matching maternal
chromosome.
- Both the same size, shape and have the same genes in the same place but are
alleles (alternate forms of the same gene) for each trait may not be the same
Plody - # of sets of chromosomes
Anaplody - # of sets of chromosomes are wrong
Down syndrome – Trisomy 21 (3 chromosomes at position 21)
- Can survive at 21 because chromosome is very small therefor not many
genes are involved
- To see if baby has down an amneosyntethis must be formed to see the
karyotype
Cell division that takes place in the reproductive organs to produce
gametes.
# of chromosome is reduced from 2n in parent cell to n in each
daughter cell
produces 4 daughter cells all different from one another + parent cell
Gametes formed = haploid
In sexual reproduction a male haploid gamete fuses with a female
during fertilization to form a diploid zygote
Mitosis Meiosis
2 identical daughter cells 4 un-identical daughter cells
1 division 2 divisions
For repair and growth Forms haploids for reproduction
Chromosome – long thread like structure that forms part of the chromatin network
(made up of DNA and histones)
- Linear in humans
Haploid number is same as
- 46 in somatic cells (normal cells) (2n – Diploid)
Bivalent number
- 23 in sex cells (n - Haploid)
Eukaryotes – found in nucleus
Prokaryotes – found in cytoplasm (nucleoid)
Karyotypes – map of organisms chromosomes
- 22 autosomes
- 1 sex chromosome
Homologous pairs – for each paternal chromosome is there a matching maternal
chromosome.
- Both the same size, shape and have the same genes in the same place but are
alleles (alternate forms of the same gene) for each trait may not be the same
Plody - # of sets of chromosomes
Anaplody - # of sets of chromosomes are wrong
Down syndrome – Trisomy 21 (3 chromosomes at position 21)
- Can survive at 21 because chromosome is very small therefor not many
genes are involved
- To see if baby has down an amneosyntethis must be formed to see the
karyotype
