Lab Meiosis

Sex cell cycle involves

Meiosis I and Meiosis II; production of gametes

Gametes

genetically unique haploid cells; sex cells; sperm and egg

Fertilization

the sperm fuses with the egg; results in a diploid zygote

4 major stages of the sex cell cycle

interphase, Meiosis I, interkinesis, and Meiosis II

how many nuclear divisions are in the sex cell cycle 

2; meiosis I and meiosis II, results in 4 haploid daughter cells 

what performs the sex cell cycle

germline cells found in male and female reproductive organs

male and female reproductive organs

testes and ovaries

Oogenesis

the oogonia produces eggs in the ovaries

spermatogenesis 

spermatogonia produce sperm in the testes 

parent germline cell is

diploid; contains homologous pair

homologous chromosomes

chromosomes of the same number, length, locus of genes etc, held together at the synapsis forming a tetrad

tetrad

pair of sister chromosomes

where does crossing over occur

where non sister chromatids pair up, this exchanges DNA and scrambles genetic variation

ploidy

number of sets of chromosomes; diploid or haploid

interphase G0

germline cell functions normally, DNA is still in chromatin form, only one centrosome 

interphase G1

centrosomes duplicate 

interphase S

DNA replication, DNA still in chromatin form 

interphase g2

histones form beads on a string

Meiosis I Early Prophase I

DNA condenses into tetrads, spindle fibers begin forming, nuclear envelope begins dissolving 

Meiosis I late prophase I

crossing over occurs between non sister chromatids, tetrads begin going to poles, nuclear envelope gone 

meiosis I metaphase I

spindle fibers attach, independent assortment occurs, tetrads line up along metaphase plate 

Meiosis I Anaphase I

Tetrad splits at synapse, move to opposite sides of cell

Meiosis I Telophase I 

New nucleus nuclear envelope reforms, DNA unravels into chromatin, actin begins forming cleavage furrow or cell plate begins forming 

Meiosis I Cytokinesis I 

cell splits into 2 haploid cells 

Interkinesis G1

centrosomes duplicate 

Meiosis II early prophase II

DNA condenses, nuclear envelope dissolving 

Meiosis II late prophase II

Spindle fibers attach, start moving to opposite poles, nuclear envelope gone

Meiosis II Metaphase II

Chromosomes alight at centromeres

Meiosis II Anaphase II

sister chromatids separated, cleavage furrow begins forming 

Meiosis II Telophase II

Nuclear envelope is back

Meiosis II Cytokinesis II

4 haploid gametes produced