Sexual Reproduction

Key Point #1 Sexual reproduction is the process in which organisms produce gametes that combine during fertilization to create a new organism. This process is important so that organisms can make more of their own kind. (ROGER!)

Meiosis is the 1st step of sexual reproduction. Key Point #2 Meiosis is the 1st step of sexual reproduction. Meiosis is a special form of cell division that occurs in the sex organs of organisms – testes (male) and ovaries (female). Meiosis produces sperm and egg cells

This diagram represents sexual reproduction in rabbits “A” represents meiosis (step 1) “B” represents fertilization (step 2)

Key Point #3 During meiosis, one cell divides into 4 gametes, or egg and sperm cells.

Draw this in your notes This is meiosis  One cell divides into ____. What is being formed here? What percent of the chromosomes does it have in relation to the parent?

Draw this in your notes: This is meiosis  One cell divides into 4 gametes. How many chromosomes are found in the parent cell? How many chromosomes are found in the gametes? What fraction or percent is this?

Key Point #4 Egg and sperm cells contain half of the DNA (chromosomes) as the parent’s normal body cells.

How is this different from MITOSIS? Characteristic Mitosis Meiosis Number of parent cells Produces Amount of DNA in daughter cells Occurs in What occurs after the process?

Let’s Practice: Copy this in your notes Organism Chromosomes in normal body cells Chromosomes in egg cell Chromosomes in sperm cell Human 23 Fruit fly 4 Corn plant 10 Cow 60 Dog 39 Elephant 56 Potato 24

Key Point #5 Step 2 of sexual reproduction is when egg and sperm cells meet. This is called fertilization.

Which method shows fertilization? A/B shows asexual reproduction. A/B shows sexual reproduction.

Key Point #6 Fertilization creates a new organism that has the same number of chromosomes as the parent: half came from mom … half came from dad.