H PART #1: MEIOSIS I

CHROMATIN

- stretched out DNA - nonvisible - unorganized - CANNOT count

individual strands example:

CHROMOSOME

- DNA with a specific, identifiable structure

- CAN see "some" (visible) - CAN count example:

CHROMATID PAIR

- chromosome with a copy of itself attached using a centromere

- ALWAYS IN PAIRS example:

HOMOLOGOUS

CHROMATID PAIR

- 2 chromatid pairs that have the same gene

example:

UNIT 7: MEIOSIS

GENE

- chemical factor on DNA that determines a specific trait

example:

ALLELE

- different forms (version) of a gene

example:

DIPLOID - 2 alleles for a particular trait

(2 sets of instructions) example:

HAPLOID - 1 allele for a particular trait (1 set of instructions) example:

PART #1: MEIOSIS I

- division of the nucleus the 1st time to produce 2 new daughter cells that are NOT identical to the parent cell - each daughter cell has ? the # of chromosomes compared to the parent cell

- PHASES INCLUDE: INTERPHASE, MEIOSIS I (prophase I, metaphase I, anaphase I, telophase I), CYTOKINESIS I

1. INTERPHASE growth stage in preparation for meiosis I & cytokinesis

#1

G1 - cell increases in size - proteins & new organelles synthesized (copies are made)

CELL GROWS

S

- DNA (chromatin) copied DNA COPIED

G2 - DNA proofread & mistakes corrected 2. MEIOSIS I

PREPARE FOR MEIOSIS I #1

PROPHASE I ? nuclear membrane dismantles around homologous chromatid pairs chromatin condense into homologous chromatid pairs centrioles (centrosomes) move to opposite sides of the cell spindle fibers form

METAPHASE I ? homologous chromatid pairs line up in the Middle across from one another centrioles now on opposite sides of the cell spindle fibers attach to centromere on both homologous chromatid pairs

ANAPHASE I ? homologous chromatid pairs separate and move to opposite sides of the cell spindle fibers separate homologous chromatid pairs & move to opposite sides of the cell

#1 #1

TELOPHASE I ? nuclear membrane reassembles around chromatid pairs

#1

chromatid pairs now on opposite sides of the cell

chromatid pairs stretch out and become less visible (resembling chromatin)

nuclear membrane reassembles around each group of chromatid pairs

3. CYTOKINESIS I

#1

#2

cytoplasm pinches around chromatid pairs (chromatin) & new organelles forms 2 new cells that are not identical to the parent cell each cell has a ? the # of chromosomes compared to the parent cell

PART #2: MEIOSIS II - division of the nucleus the 2nd time to produce 4 new daughter cells that are NOT identical to the parent cell

- each daughter cell has a ? the # of chromosomes compared to the parent cell MAKES GAMETES

- PHASES INCLUDE: MEIOSIS II (prophase II, metaphase II, anaphase II, telophase II), CYTOKINESIS II

NO INTERPHASE IN MEIOSIS II

Explain why there is not Interphase in Meiosis II.

4. MEIOSIS II

#1

PROPHASE II ? nuclear membrane dismantles around chromatid pairs chromatin condense into chromatid pairs centrioles (centrosomes) move to opposite sides of the cell spindle fibers form

#1 METAPHASE II ? chromatid pairs line up in the Middle

centrioles now on opposite sides of the cell

spindle fibers attach to centromere on both sides of each chromatid pair

ANAPHASE II ? chromatid pairs separate and move to opposite sides of the cell

#1

spindle fibers move & separate chromatid pairs into individual chromosomes

to opposite sides of the cell

#2 #2 #2

TELOPHASE II ? nuclear membrane reassembles around individual chromosomes

individual chromosomes now on opposite sides of the cell

#1

individual chromosomes stretch out and become less visible

(resembling chromatin)

nuclear membrane reassembles around each group of

individual chromosomes

#2

5. CYTOKINESIS II

cytoplasm pinches around individual chromosomes

(chromatin) & new organelles

forms 4 new daughter cells that are not identical to the parent cell

each cell has a ? the # of chromosomes compared to the parent cell

NEW daughter cells are GAMETES

#1

#2

#3

#4

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