- MEIOSIS -
MEIOSIS I:
Pairing of Homologous
• At the start of meiosis I the homologous chromosomes (homologs) pair up due to
centromere position and gene loci.
• The homologs replicate forming two sister chromatids (each). These can also be
called homologous pairs.
• Protein strands link the sister chromatids and the homologous pairs to form a
bivalent.
Extra info:
• Homologous chromosomes are chromosomes of the same size.
• Same centromere position is the same sequence of genes at the same loci.
Crossing over
• A chiasma forms at a random position between the homologous pairs.
• Human chromosomes usually have 2 or 3 chiasmata.
• Chiasmata never form between sister chromatids.
• They allow the shuffling of sections of DNA between homologs, a process called
crossing over.
• Crossing over leads to the recombination of linked genes, and so helps to increase
variation in the gametes.
MEIOSIS I:
Pairing of Homologous
• At the start of meiosis I the homologous chromosomes (homologs) pair up due to
centromere position and gene loci.
• The homologs replicate forming two sister chromatids (each). These can also be
called homologous pairs.
• Protein strands link the sister chromatids and the homologous pairs to form a
bivalent.
Extra info:
• Homologous chromosomes are chromosomes of the same size.
• Same centromere position is the same sequence of genes at the same loci.
Crossing over
• A chiasma forms at a random position between the homologous pairs.
• Human chromosomes usually have 2 or 3 chiasmata.
• Chiasmata never form between sister chromatids.
• They allow the shuffling of sections of DNA between homologs, a process called
crossing over.
• Crossing over leads to the recombination of linked genes, and so helps to increase
variation in the gametes.
