Where do babies come from? Warm Up 1. A particular species of shark normally reproduces sexually. In captivity, it was found that a female could also reproduce asexually. 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 PowerSchool and Grades Academic and Behavior Expectations Test on Thursday (Formal grade) Science Fair Hypothesis Due Wednesday 02/11

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!

2 Forms of Cell Division 46 46 92 92 46 46 46 46 23 23 23 23

Mitosis 46 92 _____________ 46 46

Mitosis Meiosis 46 46 92 92 46 46 46 46 23 23 23 23 ________

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 All other cells besides gametes are called “body cells” have two of each type of chromosome- they come in pairs. but gamete cells only have one of each type.

How does meiosis lead to variation in offspring?

How does meiosis lead to variation in offspring How does meiosis lead to variation in offspring? Gene Sorting and Recombination!

Are each of these sperm genetically identical? 4 8 2

Are each of these sperm genetically identical? 4 8 2 No! This is called Gene Sorting

How does meiosis lead to variation in offspring 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 How does meiosis lead to variation in offspring? Recombination- a process where parts of chromosomes are swapped during meiosis to increase variation

Stop and Jot Identify one process that occurs during meiosis which increases variation. Explain how it increases variation.

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

2. The body cells of a kangaroo contain 12 chromosomes 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 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_________