Warm Up1. A particular species of shark normally reproduces sexually. In

captivity, it was found that a female could also reproduceasexually. One negative result from asexual reproduction is

(1) increased mutations(2) increased number of males produced (3) decreased number of eggs used (4) decreased variation within the species

2. When an organism is growing it needs to create new body cells from existing cells. A body cell can divide to create an identical copy of itself for this purpose. This process of cell division is called

(1) fertilization (2) mitosis (3) replication (4) gene splicing

3. Sexually reproducing organisms require gametes to pass on and combine their genetic information. Identify the male and female gamete in humans.

Male gamete __________________Female gamete________________

Announcements

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• Academic and Behavior Expectations– Fetal Pig Dissection

• Test on Thursday (Formal grade)

• Writing Task due two weeks from Friday (Formal grade)

Why is it that organisms that reproduce sexually have so much

variety?

Why is it that organisms that reproduce sexually have so much

variety?Meiosis!

46

46 46

92

46

46 46

92

23 23 23 23

2 Forms of Cell Division

46

46 46

92

Mitosis

_____________

46

46 46

92

46

46 46

92

23 23 23 23

Meiosis

________

Mitosis

Mitosis- form of cell division that results in 2 daughter cells that are identical to the parent cell

Meiosis-_________________________________________________________________________________

Site of Meiosis___________________________

Genetic Information in Human Cells

Body Cells- 46 Gamete Cells- 23

How does meiosis lead to variationvariation in offspring?

How does meiosis lead to variationvariation in offspring?

Gene Sorting and Recombination!

Are each of these sperm genetically identical?

4

8

4 4

2 2 2 2

Are each of these sperm genetically identical?

4

8

4 4

2 2 2 2

No! This is calledGene Sorting

How does meiosis lead to variation in offspring?

Recombination- a process where parts of chromosomes are swapped during meiosis to increase variation

How does meiosis lead to variation in offspring?

Recombination- a process where parts of chromosomes are swapped during meiosis to increase variation

Stop and JotIdentify one process that occurs during

meiosis which increases variation. Explain how it increases variation.

Partner Practice

1. Meiosis occurs within structure(1) A (2) B (3) C (4) D

2. The body cells of a kangaroo contain 12 chromosomes. How many chromosomes would be present in a kangaroo cell produced by mitosis?(1) 3 (2) 6 (3) 12 (4) 24

3. The body cells of a kangaroo contain 12 chromosomes. How many chromosomes would be present in a kangaroo cell produced by meiosis?(1) 3 (2) 6 (3) 12 (4) 24

4. True or False?– A. Mitosis creates cells that have half of the normal

number of chromosomes _________– B. Meiosis is the process of cell division that is used

to create body cells _________– C. Daughter cells produced by meiosis are genetically

identical to their parent cells _________– D. The process of mitosis leads to increased genetic

variation among cells_________