MITOSIS AND MEIOSIS!!!!!!!!!!!!!!!!!!!!!!!!!!

I'm a little hyper i really don't know why but OK blogging ummm.... this week we learned about meiosis.

MEIOSIS

What is it???

Meiosis is the division of cells in which four-daughter cells are produced from one " parent cells " each with half the genes of the parent.

Meiosis is a special kind of cell division that produces haploid (1n) cells.

parent cells divide into two daughter off springs with half number of chromosomes in each new cell.

What are the phases??

Events during Meiosis

Diploid Cell (2N): From a preceding mitotic division, the Oogonium (Spermatogonium) enters meiosis with DIPLOID (2N) chromosomes but TETRAPLOID (4N) DNA. Chromosomes then duplicate to produce SISTER CHROMATIDS (or HOMOLOGOUS DYADS).

Prophase I: Dyad pairs align to create "TETRADS", non-sister chromatids connect and trade sections at a "CHIASMA", a process called "CROSSING OVER".

Metaphase I: SPINDLE FIBERS attach to each dyad at the KINETOCHORE. Tension from spindle fibers aligns the tetrads at the cell equator.

Anaphase I: Chiasmata break apart and sister chromatids begin migrating toward opposite poles.

Telophase I: CLEAVAGE FURROW forms beginning the process of CYTOKINESIS (cell division). Resulting daughter cells are HAPLOID (1N).

Prophase II: Spindle formation begins and centrosomes begin moving toward poles.

Metaphase II: Tension from spindle fibers aligns chromosomes at the metaphase plate.

Anaphase II: CHRO

MATIDS separate and begin moving to the poles.

Telophase II: CLEAVAGE FURROW forms beginning CYTOKINESIS.

Gamete (1N): NUCLEAR ENVELOPES form and chromosomes disperse as CHROMATIN. Meiosis has produced 4 DAUGHTER CELLS, each with 1N chromosomes and 1N DNA. Later, in fertilization, male and female 1N gametes will fuse to form a 2N ZYGOTE.

What do the phases look like???

Besides that im doing pretty good in science i got an A on my test and an A on my mitosis test.

i learned all these thing by listening to mr Finley during class and writing done what i need to write down during class!!!!!!!!!!!!!!!!!!!!!!!!

ciao!!!!!!!!!!!!!!!!!!