1. Meiosis
Notes 1 Ch
Meiosis

2. Parent can produce many types of offspring .
Families will have resemblances, but no two are exactly alike

3. Every cell has a nucleus Every nucleus has chromosomes
The number of chromosomes depends on the species
Ex: Humans Chimpanzee 48
have Chicken
have 46 Frog
Pea

4. Genes control the TRAITS of the individual
Genes are located on chromosomes
Genes control the TRAITS of the individual

5. Chromosomes come in matching sets-these are called homologous pairs
Same length
Same centromere position
Carry genes that control same inherited traits

7. Cells in your body have a complete set (all 46) - they are called DIPLOID (2n)
Sex Cells ( sperm and egg) only have half (23) – they are called HAPLOID (n)
Gametes: sex cells that have half the number of chromosomes

8. Meiosis Cell division that reduces the # of chromosomes
Occurs in reproductive structures
Reduces chromosome # through separation of homologous chromosomes

14. Objective: List the stages of meiosis and what is happening in those stages
Warm Up: List this stage of mitosis and explain what is happening here.

15. Interphase
Replication of DNA
Synthesis of proteins

16. Prophase I
Chromatids match up with their Homologous pairs and fasten together in a process called synapsis.
Crossing over: Trade gene segments between the pair of homologous chromosomes. (exchange genetic material)
EXTREMELY IMPORTANT!! THIS IS THE PHASE WHERE CROSSING OVER CAN OCCUR

19. Metaphase I
The homologous chromosomes line up as pairs at the equator.
* diff from mitosis

21. Anaphase I Homologous pairs separate
Still consist of 2 sister chromatids

23. Telophase I Consist of 2 sister chromatids
The cytoplasm divides, forming two new daughter cells.
end of the first meiotic cell division.
Each of the newly formed cells has half the number of the parent cell’s chromosomes, but each chromosome is already replicated ready for the second meiotic cell division

25. Cytokinesis Occurs simultaneously with telophase I
Forms 2 daughter cells

27. Prophase II
Chromosome condense
Spindle apparatus form

29. Metaphase II
Haploid # of chromosome line up at the equator

31. Anaphase II
Sister chromatids pulled apart at the centromere by spindle fibers and sister chromatids move toward opposite poles of the cell

33. Telophase II Chromosome reach the poles
Nuclear membrane and nuclei reform

35. Cytokinesis
Results in 4 haploid cells (n)