Agenda Quiz Notes Whiteboards Meiosis Worksheet Constructed response practice Exit slip

Differences between mitosis and meiosis MEIOSIS is for… MITOSIS is for… reproduction growth

Key Point #1 When one sperm fertilizes one egg it forms a zygote. This zygote then grows into a full grown organism over time.

½+ ½ = 1  A zygote gets HALF its chromosomes from mom and HALF from dad. 1. An egg has ½ the chromosomes of all body cells. 2. A sperm has ½ the chromosomes of all body cells 1/2 1/2 1

What’s N got do with it? 2N 4N Haploid- Half the number of chromosomes We call this “N” chromosomes If sex cells had 2N chromosomes like body cells, then babies would have 4N!!! 2N N 2N 4N 2N N

Key Point #2 The process of making gametes (sex cells) is called meiosis. Meiosis produces four genetically different sex cells. End with FOUR sperm or egg cells Start with one cell Meiosis happens

Meiosis produces gametes (sex cells) sperm egg

Meiosis produces genetically different daughter cells Every sperm and egg are different. This is why siblings aren’t twins!

Meiosis produces FOUR daughter cells

Meiosis goes through cell division TWICE!!!! IPMATC and then… PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II CYTOKINESIS II

Meiosis produces daughter cells with N chromosomes Parent cell= 100 chromosomes (2N) Daughter cells= 50 chromosomes (N) ***Daughter doesn’t have to be a girl  It just what scientists call the cells produced in mitosis/meiosis

Let’s use humans as an example so we can understand the numbers better!

mom dad 46 Original Cell Original Cell 46 46 23 23 23 23 23 23 23 23 YOU 23 46 Meiosis Sex Cells (Eggs) Meiosis Sex Cells (Sperm)

Whiteboards

Choices: meiosis OR mitosis This process produces somatic cells

Choices: meiosis OR mitosis This process produces daughter cells that are EXACT genetic copies of the parent cell

Choices: meiosis OR mitosis This produces four daughter cells

Choices: meiosis OR mitosis Which process is responsible for this?

Choices: meiosis OR mitosis Which process is responsible for this? Drew Brees and his son

Choices: meiosis OR mitosis Which process is responsible for this?

Tooooo easy, let’s make it harder!

What phase?

A cell has 24 chromosomes. How many daughter cells will be produced if it goes through mitosis?

How many chromosomes will each of the TWO daughter cells have?

A cell has 50 chromosomes. If it undergoes meiosis, how many daughter cells will be produces?

How many chromosomes will EACH of the FOUR daughter cells have?

A cell has 20 pairs of chromosomes A cell has 20 pairs of chromosomes. If it undergoes mitosis, how many PAIRS of chromosomes will the daughter cells have?

If a cell has 10 PAIRS of chromosomes and it undergoes mitosis, how many chromosomes total will each daughter cell have?

Oooook even more challenging!

Oooook even more challenging! You are a scientist looking at the sperm cells of Orca Whales under a microscope. Each of these sperm cells has 22 chromosomes. How many chromosomes would you expect to find in a lung cell of an orca?

1. Mitosis or meiosis? 40

40 ? ?

40 ? 40 40