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Meiosis - Coggle Diagram
Meiosis
Meiosis 2
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they are haploid - have just 1 chromosome from each homologous pair - but the chromosomes still have 2 sister chromatids joined by the centromere
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Prophase 2
chromosomes condense, nuclear envelop breaks down, centrioles move apart to opposite poles of cell & spindle fibres begin to form
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Metaphase 2
chromosomes line up individually at equator of cell, 2 sister chromatids of each chromosome are captured by spindle fibres form opposite centrioles
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Telophase 2
nuclear membranes form around each set of chromosomes & the chromosomes decondense to form chromatin
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Cytokinesis
splits the cytoplasm, forming the final products of meiosis - 4 haploid cells in which each chromosome has just 1 chromatid
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Meiosis 1
before entering meiosis 1 a cell goes through interphase growing during G1 & coping chromosomes in S phase & prepares for division in G2 phase
Prophase 1
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so far same as mitosis, during prophase 1 each chromosome starts to pair up with is homologous pair
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Metaphase 1
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BUT, during meiosis each chromosome attaches to spindle fibres from just 1 pole of the cell
during metaphase 1, homologous pairs of chromosomes - not induvial chromosomes - line up at equator of cell
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Anaphase 1
homologous pairs are pulled apart to opposite poles of cell - sister chromatids of each chromosome remain attached by centromere
each chromosome is moved when spindle fibres contract with help of motor proteins which 'walk' along the spindle fibre microtubules & carry the chromosomes
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Telophase 1
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once separated chromatid reach the poles spindle fibres begin to disintegrate into their building blocks as they are no longer needed
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Homologous Chromosomes
in human body cells there are 46 chromosomes (23 pairs) - 23 from mother's egg nucleus & 23 from father's sperm nucleus
the maternal chromosome & the paternal chromosome contain the same genes at the same places (loci - pl, locus - sing) along the chromosome
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= matching chromosomes, containing the same genes at different (loci) places, may contain different alleles for some of the genes
karyotype
a photomicrograph of chromosomes in a cell, showing the pairs of homologous chromosomes
meiosis
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= type of nuclear division hat results in the formation of cells containing 1/2 the number of chromosomes (haploid) of the parent cell
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