-
fertilization
- a haploid sperm fuses with a haploid egg ->hapliod gametes
- ->fertilized egg = zygote (diploid)
-
Repoduction/ Life cycles
Meiosis -> Gamates haploid -> Fertilization -> Zygote dipliod (human/ animal)
- 3types :
- -Haploid multicellular organism (Plants/algae)
- -Haploid unicellula/multi organism (fungi/protist/algae)
-
alternation of generations (Haploid multicellular organism (Plants/algae)
- Sporophyte -> gametophyte (Mitosis)-> sporophyte
- Plants and some species of algae exhibit a second type of life cycle
- includes both diploid and haploid stages that are multicellular.
- sporophyte - multicellular diploid stage
- gametophyte - multicellular haploid stage
-
Haploid unicellula/multi organism (fungi/protist/algae)
Meiosis produces not gametes but haploid cells that then divide by mitosis and give rise to eitherunicellular descendants
-
homologous pair
- individual chromosomesthat were inherited from different parents
- have different versionsof genes, each called an allele at loci
-
Meiosis I (2n + 2n) -> Meiosis II(4(n) daughter cells gamates)
reductional division->equational division(sister chromotids seperate to chromosome)
- Interphase(duplicate homologous chromosome)
- ->Prophase I (synapsis, crossing over, chiasmata(X shaped) -> Metaphase I (line up, centrsome fiber connect) -> Anaphase I (seperate aparat homologous) -> Telophase I ( nuclear evelope is forming, seperate)
-
Origins of Genetic Variation Among Offsping
- -Independent Assortment of Chromosomes
- -random orientation of pairs of homologous chromosomes(maternal or paternal) at metaphase I
- -possible combinations : 2^n Ex: human= 2^
- -Crossing Over
- -
recombinant chromosomes: carry genes (DNA) derived from two different parents, a paternal chromatid is joined to a piece of maternal chromatid - -Random Fertilization
- -
each male and female gamete represents one of about 8.4 million -> 70 trillion zygote
|
|