1. Bell Ringer
Objective:
Question: Page 7 of POD

2. What is meiosis?
You have 15 minutes. Use your Chromebook & Biology books.
Turn something in that answers these six questions:
What is the purpose of meiosis?
What does it look like?
Why is it called reduction division?
Define diploid and haploid. Provide examples of each.
Explain crossing over.
How does this relate to content we have already learned in this year?

3. MEIOSIS (making sperm and egg cells)

4. DNA Passes from Parent to Offspring
What are the two types of reproduction?

5. Review of Chromosomes Chromosome → __________________
____________________________________
Normal cells = diploid (2n) → 2 copies of each chromosome
In diploid cells, 1 copy came from each parent (people: 1 from mom, 1 from dad)

6. What is meiosis?
Meiosis → special cell division for sexual reproduction
Produces haploid (1n) cells → 1 copy of each chromosome
Haploid cells = gametes (sperm/eggs)
Human gametes:
In ♂, meiosis produces (in testes) 4 sperm cells
In ♀, meiosis produces (in ovaries) 1 egg cell and 3 polar bodies (that later disintegrate)
Mitosis: cells divide once
Meiosis: cells divide twice

7. From diploid (2n) to haploid (n).
Why do ovary and testes cells go through meiosis?
Meiosis is “reduction division.” It reduces the chromosome number in the gametes by one half.
From diploid (2n) to haploid (n).
Why do meiosis?

8. Chromosome numbers… In humans, 2n = 46
A normal body cell has 46 chromosomes → 23 came from mom, 23 from dad; each set of 23 from mom is similar to the set of 23 from dad
In humans, n = 23
A normal gamete has half the normal chromosome number (n) → just one set

9. Chromosome number questions
If a horse retina cell has 36 chromosomes, how many chromosomes does a horse sperm cell have?
If n= 4 for fruit flies, how many chromosomes does a wing cell have?
If the 2n number of a pine tree is 86, how many chromosomes would be found in a pine ovum?
If n = 16 for goldfish, how many chromosomes are in a fin cell?

10. Homologous Pairs
Homologous pairs  Pairs of chromosomes with the same sequence of genes
One is from mom, one is from dad
Genes are in the same order, but not identical

11. Phases of Meiosis Remember mitosis? (I)PMAT…
In meiosis, each phase occurs twice
Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis I
Meiosis II: Prophase II, Metaphase II, Anaphase II, and Telophase II, Cytokinesis II

12. Meiosis I
In Prophase I, homologous chromosomes pair up in a tetrad (group of four)
same gene sequences, same banding pattern, same position of centromere
Crossing-over takes place

13. A Sketch of Chromosomes Crossing Over (Prophase I)
During crossing-over, homologous chromosomes* exchange pieces of DNA. Wwwhhhyyy?
**What does homologous chromosome mean?
Same size and similar structure.

14. Meiosis and Sexual Reproduction: Practice
Which of the following types of cells would experience mitosis, meiosis, or both? Write ME for meiosis, MI for mitosis.
____A pollen cell of a plant
____A leaf cell of a plant
____A root cell of a plant
____The cells in the petal of a flower
____Stem cells
____Kidney cells
____Liver cells
____Testes cells
____Ovary cells
____Tree bark cells

15. Task #1-3

16. Closure What is the difference between a gene, chromosome, and DNA?
What cells are considered haploid?
What is the 10% rule?
Which macromolecule is responsible for long term energy storage?
What type of cells are pictured below?

18. Bell Ringer
Which word do we use to describe a cell that has a single set of chromosomes?
How would you describe diploid?
What is a somatic cell? Give examples.
If an eye cell in a monkey has 20 chromosomes, how many chromosomes will be found in its sperm cell?
What is the difference between meiosis and mitosis?

19. Meiosis I results in 2 haploid daughter cells

20. Meiosis II
Meiosis
Each of the haploid daughter cells from meiosis I divide again to make 4 haploid cells.

21. Comparing Mitosis and Meiosis
The processes of mitosis and meiosis are very similar, but with some important differences:
Mitosis
Includes only 1 cycle of cell division
Occurs in body cells (somatic cells)
No crossing over of chromosomes
Results in two genetically identical diploid cells
Metaphase: 1 duplicated chromosome per spindle fiber
Meiosis
Includes 2 cycles of cell division (meiosis I and meiosis II)
Occurs only in sex cells (gametes)
Chromosomes cross over in Prophase I
Results in four genetically different haploid cells
Metaphase I: 2 duplicated chromosomes per spindle fiber

23. Interphase DNA replication occurs
DNA is in chromatin form (unwound, like spaghetti)

24. Prophase I DNA condenses to form chromosomes
Homologous chromosomes pair up to form tetrads
Crossing over takes place

25. Metaphase I Homologous pairs line up along center of cell
1 homologous chromosome and its duplicate are attached to each spindle fiber

26. Anaphase I
Homologous pairs separate, move to opposite ends of the cell

27. Telophase I
Nuclear membrane reappears
Spindle fibers disappear

28. Cytokinesis Cytoplasm of the two cells separate
Meiosis I results in 2 haploid cells that are genetically different

29. Prophase II
The 2 haploid cells from Meiosis I will divide again

30. Metaphase II
Chromosomes (set of sister chromatids) line up along the center of the cell
1 sister chromatid attaches to each spindle fiber

31. Anaphase II
Centromeres split, sister chromatids are pulled apart

32. Telophase II and Cytokinesis
Cytoplasm divides, resulting in 4 genetically different haploid cells

33. Bell Ringer Go to weebly under the meiosis tab
Read the kidsahead.com  Live Science Reading.
Answer questions based on reading.

34. The Creation of Life

35. Create a child
Definitions on the back side FIRST if you don’t do this you will be STUCK on the front. Show me to get your penny.
EVERYONE WILL NAME THEIR BABY ARDREY. If you don’t enjoy your zero.
Draw baby under vocab
When finished hand in & you may begin your homework.

36. Closure What is a genotype? What type of cell undergoes meiosis?
Is a liver cell said to be haploid or diploid?
How many times does a cell divide during meiosis?
What is a chromosome?
What are the 6 kingdoms?

37. Homeroom: Door Decorating Challenge
Guys vs Girls: Winner gets candy on Friday.
Choose your door.
Voted on by the biology teachers.
May use any resources from station #7.
If you don’t participate. No candy for you.