199725
Description
Mind Map by pwincess_sana97, updated more than 1 year ago
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Created by pwincess_sana97
over 10 years ago
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Meiosis, gametes, fertillisation
- meiosis = cell division - creating gametes
- gametes formed by meiosis in ovaries and testes
- gametes = sex cells = eggs and sperm
- body cell of mammals =
diploid - has 2 copies of each
chromosome in its nucleus -
one from female + one from
male
- gametes are haploid - 1 copy of each
chromosome - combine=diploid
- gametes are haploid - 1 copy of each
chromosome - combine=diploid
- body cell of mammals =
diploid - has 2 copies of each
chromosome in its nucleus -
one from female + one from
male
- gametes = sex cells = eggs and sperm
- gametes formed by meiosis in ovaries and testes
- meiosis = 2 divisions
- 1. starts the same way as mitosis - DNA replicates -
curls up into double armed chromsomes
- 2. after replication - chromosomes arrange
themselves into pairs - humans = 23pairs of
chromosome = 46 altogether
- chromosomes in a pair contain info about the same features
- 3. 1st division the pairs split up - chromosomes in
each pair move to opposite poles. in each of two new
cells there are no pairs- one of each of the 23
different types- each new cell = mixture of mum +
dads chromosomes- only half the usual number of
chromosomes
- 4. 2nd division = each chromosome splits in half and one arm ends up in each new cell.
- 4. 2nd division = each chromosome splits in half and one arm ends up in each new cell.
- 3. 1st division the pairs split up - chromosomes in
each pair move to opposite poles. in each of two new
cells there are no pairs- one of each of the 23
different types- each new cell = mixture of mum +
dads chromosomes- only half the usual number of
chromosomes
- chromosomes in a pair contain info about the same features
- 2. after replication - chromosomes arrange
themselves into pairs - humans = 23pairs of
chromosome = 46 altogether
- 1. starts the same way as mitosis - DNA replicates -
curls up into double armed chromsomes
- fertilisation creates genetic variation
- male + female gametes join =
diploid cell. cell = zygote.
- characteristics of the zygote are
controlled by the combination of
genes on its chromosome.
- zygote inherited chromosomes from parents-
features of both parents wont be exactly like them.
- male + female gametes join =
diploid cell. cell = zygote.
- sperm cells are adapted for their function
- small, long tails = swim to egg
- lots of mitochondria = energy needed to swim
- acrosome at the front of the head- releases enzymes
to digest their way through the membrane of the cell
egg
- acrosome at the front of the head- releases enzymes
to digest their way through the membrane of the cell
egg
- lots of mitochondria = energy needed to swim
- small, long tails = swim to egg
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