Gamete cell reproduction

what are gametes?

sperm and egg cells

What is the purpose of Meiosis?

To produce gametes which contain HALF the genetic material as the parent cell

What are the parent cells of gametes?

Reproductive cell / Germ cell

Germ Cells turn into?

Gametes (sperm and egg)

Meiosis has how many PMAT phases?

2 PMAT phases

before a cell goes through meiosis what must it go through before?

Interphase (DNA replication)

What is the process called synapsis?

• a duplicated chromosome seeks out its homologous pair and forms a tetrad

• occurs during meiosis during Prophase 1

what is a tetrad?

• 4 chromoatids carrying the same genetic material

• Homologous

Prophase 1

• each duplicated chromosome seeks out its homologous pair in a process called synapsis and forms a tetrad

• crossing over may occur

what is crossing over?

exchange of segments which allows for the recombination of genes and gives rise to genetic variation

Metaphase 1

• Spindle fibers attatch to each chromosome

• Tetrads line up along the equator of the cell

• 2n - diploid

Anaphase 1

• homologous chromosomes of each tetrad seperate and go to opposite poles of the cell

• 2n - diploid

Telophase 1

• cytoplasm pinches off to create 2 new cells

• 2n - diploid

• 2 new cells are haploid (n)

Prophase 2

• nuclear membrane and nucleolus dissolve

• chromatin condenses into chromosomes

• centrioles move to opposite poles of the cell

• spindle fibers start to form

• n - haploid

Metaphase 2

• chromosomes of each daughter cell line up along the equator of the cell

• spindle fibers attach to the chromosomes

• n - haploid

Anaphase 2

• the chromatids of each chromosome seperate and go to oppposite poles of the each cell

• n - haploid

Telophase 2

• for new daughter cells are formed containing half the # of chromosomes as the original parent cell

• 4 new daughter are haploid (n)

Gametogenis

• spermatogenesis

• oogenesis

Spermatogensis

• the proccess of meiosis to generate 4 haploid sperm cells

• occurs in the testes

oogenesis

• the proccess of meiosis to create an egg cell, ovum or ova

• only one ovum produced

• remaining cells are polar bodies and not released during ovulation

• occurs in the ovary

sperm

• small

• before release (fat)

• after release (fructose)

• 50 - 100 mitochondria / cell

• motile (can move itself)

• 300 - 500 million produced

egg

• large

• can only live for one day if unfertilized

• 140 000 mitochondria

• not motile

• one every 28 days