Cell Divison: MEIOSIS

Meiosis

The cell division that produces 4 (may become gamete) haploid cells, includes 2 parts (PMAT I and PMAT II)

Crossing over

the exchange of genetic material between homologous chromosomes resulting in new combinations of genes on each chromosome (Occurs during Prophase I)

PMAT I

The first part of Meiosis

Prophase I

Nuclear envelope begins to break down; chromosomes condense. centrioles start moving to opposite cell poles; spindle starts forming. Homologous chromosomes pair up.

Metaphase I

Spindle fibers attach to the paired homologous chromosomes. The

paired chromosomes line up along the equator (middle) of the cell.

Anaphase I

The chromosomes of each homologous pair start to separate from each other.(bc the spindle fibers shorten) The chromosomes move to opposite poles of the cell

Telophase I

The spindle breaks down, and new nuclear membranes form.

Cytokensis of MEIOSIS after PMAT I produces

The cytoplasm of the cell divides, and two haploid daughter cells result.

-The daughter cells each have a random assortment of chromosomes, with one from each homologous pair.

-Both daughter cells go to meiosis II.

Prophase II

Nuclear envelope begins to break down

-chromosomes condense

-centrioles move to oppo. poles of the cell;separate, and

-spindle begins to form in each haploid daughter cell from meiosis I.

Metaphase II

Spindle fibers attach to the paired homologous chromosomes. The

paired chromosomes line up along the equator (middle) of the cell.

Anaphase II

-Spindle fibers shorten

-Sister chromatids separate and move to opposite poles.

-The centromere divides.

Telophase II & Cytokenisis

The spindle breaks down, and new nuclear membranes form.

-The cytoplasm of the cell divides, and two haploid daughter

cells result.

-The daughter cells each have a random assortment of

chromosomes, with one from each homologous pair.

Sexual reproduction can…

produce genetic variations in offspring, that are different, due to crossing over during meiosis.

Asexual reproduction

involves one parent and produces offspring that are genetically

identical to each other and to the parent.

Sexual reproduction

involves two parents and produces offspring that are genetically

unique.

Crossing over

the exchange of genetic material between homologous chromosomes occurs

Independent Assortment

different chromosomes segregate independently of each other.

Random Fertilization

chance of fertilization of two gametes from many possibilities.

Crossing-over, independent assortment, and the random union of gametes work together to result in…

genetic variation

life cycle

A life cycle is the sequence of stages an organism goes through from one generation to the next.

Cell Theory

- All cells come from preexisting cells through the process of cell division.

- The cell is the basic unit of life

- All organism is made up of cells.