Reproduction Flashcards
What is the acrosome reaction
Membrane of thr acrosome fuses with the sperm cell membrane
Releasing digestive enzymes from the acrosome
To break down the zone pellucida
By exocytosis
Fertilisation after acrosome reaction
Fusion of sperm cell membrane with egg cell membrane
Cortical granules release contents into zona pellucida
Cortical granules content react with zona pellucida causing it to thicken
Fusion of egg nuclei and sperm nuclei
Why does preventing shortening of spindle fibres affect mitosis
Sister chromatids can’t be pulled apart at the centromere
Stuck in metaphase/ anaphase can’t occur
Daughter cells produced with incorrect number of chromosomes
Why are offspring genetically different
Each zygote is formed from different gametes
Each gamete has different combinations of alleles
Which is due to independent assortment and crossing over
What is a sex linked disorder
A disorder is caused by a mutated/ faulty allele
Located on xy chromosome
So disorder is more likely in one gender than the other
How does crossing over produce gametes with new combinations of alleles
Crossing over of non sister chronatids produces chromatids with different combinations of alleles
Why is DNA replicated before mitosis
To ensure daughter cells have diploid number of chromosomes so daughter cells are genetically identical
What happens during prophase in mitosis
Nuclear membrane breaks down
chromosomes condense
Spindle fibres form
Centrioles migrate to opposite poles of cell
How do chromosomes appear during metaphase
Condensed /visible
Seen as pairs of chronatids held together by centromere
Joined to spindle fibres
Aligned along equator of cell
Three stages of cell cycle
- Interphase
- Mitosis
- Cytokinesis
How does crossing over increase genetic diversity
Swapping of alleles between non sister chromatids
Of a homologous pair of chromosomes
Resulting in different combinations of alleles
