In Prophase I:
- The duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids.
- DNA is exchanged between homologous (similar) chromosomes in a process called 'homologous recombination'.
- This often results in the non-sister chromatids crossing over*. The new combinations of DNA created during crossover are a significant source of genetic variation.
*at points called chiasmata (plural; singular chiasma).
The homologous pairs of chromosomes line up together forming tetrads. During this time, chromatids from the homologous chromosomes cross over and exchange segments so that each chromatid contains both maternal and paternal DNA.
a new spindel forms around the chromosomes
crossing over of homologous chromosomes
snyapsis
meiosis
during the pachytene stage of prophase-1 of meiosis -1 of meiosis ,the X shaped structure chiasmata is observed
At the beginning of Prophase 1 during meiosis. It occurs in a sub-stage of Prophase 1 called Leptonema.
The formation of tetrads are formed during p1(prophase 1)
yes crossing-over occurs in meiosis also known as genetic drifting
Crossing over occurs during Prophase I of meiosis.
meiosis
during the pachytene stage of prophase-1 of meiosis -1 of meiosis ,the X shaped structure chiasmata is observed
At the beginning of Prophase 1 during meiosis. It occurs in a sub-stage of Prophase 1 called Leptonema.
Tetrads line up in the middle of the cell during metaphase I.
Mistakes such as nondisjunction can occur during meiosis. This is the result of chromosomes failing to separate equally during either anaphase.
After the pachytene stage, or in the end of it.
Yes, the nucleus dissipates during late prophase and early metaphase in mitosis, and during Prophase 1/diakinesis of meiosis.
Each chromatid can synapse with any one it want/chooses.
The formation of tetrads are formed during p1(prophase 1)
The purpose of synapsis in meiosis is to increase genetic variability. It does this as the homolog pairs match up, which means there are 4 chromosomes of like, but possibly unique, DNA data in the grouping. This allows the cell. as it proceeds through Anaphase 1 and Anaphase 2 to separate the individual chromosomes first into 2 pairs then as individuals, which inturn adds to the variability as 1 chromosome goes to each daughter cell. .
yes crossing-over occurs in meiosis also known as genetic drifting