Meiosis

Meiosis and Cell Cycle Review

Engage

The Meiosis Dance

Explore

Sockosomes - You will use a hands-on manipulative that will allow you to take a cell from the beginning of meiosis to the end.

Mitosis/Meiosis Manipulative

Explain: Think Back to Mitosis!!!

What is mitosis? What were the different phases of the cell

cycle? What happened in G1? S? G2? What were the phases of mitosis?

Asexual vs. Sexual Reproduction

Mitosis Asexual: CLONES

– Single parent

– Passes all genes from one parent

– Offspring genetically identical

Meiosis Sexual: VARIATION

– Two parents

– Each parent passes half of their genes

– Offspring have unique genetic combination

Meiosis, Slide 1

Preceded by chromosome replication, but is followed by TWO cell divisions (Meiosis I & Meiosis II)

4 daughter cells; 1/2 chromosome number (1N); variation

Meiosis, Slide 2

Meiosis I Prophase I Metaphase I Anaphase I Telophase I and

Cytokinesis

Meiosis II Prophase II Metaphase II Anaphase II Telophase II and

Cytokinesis

Prophase I

Chromosomes condense Synapsis occurs:

Homologous pairs (Tetrads) come together

Centriole pairs move apart Nuclear envelope and

nucleoli disperse Chromosomes begin to

move to equator

Crossing Over

Only Crossing Over Meiosis Crossing Over

Metaphase I

Tetrads are aligned

Anaphase I

Tetrads separate and are moved towards the poles

Sister chromatids remain attached

Telophase I and Cytokinesis

Cytoplasm Division Does NOT replicate

chromosomes again at this point

Getting ready for second division

Prophase II

Spindle apparatus forms and chromosomes move towards the Metaphase II plate

Metaphase II

Chromosomes align singly

Sister chromatids point towards opposite poles

Anaphase II

Sister chromatids separate

Telophase II and Cytokinesis

Nuclei form at opposite poles of the cell.

Cytoplasm divides four haploid (N) daughter cells are produced.

Sperm Eggs

Spermatogenesis Oogenesis

Meiosis vs. mitosis

Synapsis/tetrad/ (prophase I)

Homologous

(metaphase I) Tetrads Separate

(anaphase I) Meiosis I separates

homologous pairs of chromosomes, NOT sister chromatids of individual chromosomes.

Sister Chromatids join not homologous chromosomes or tetrads (Prophase)

Individual chromosomes

(Metaphase) Sister chromatids separate

not tetrads (Anaphase)

Elaborate

You will now complete a Flow Chart comparing Mitosis and Meiosis.

You will also complete a chromosome number worksheet to help solidify the haploid/diploid concept.