19 20 21 22 Y X

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18 7

Look at the spread of human chromosomes (Called Karyotype):

1) List at least three facts that you can observe.

2) Why do the chromosomes come in pairs?

. So that the chromosomes are paired up by size, shape, and pattern of bands.

The microscopic image of the chromosomes can be re-arranged,

In humans… There are 46 chromosomes, or 22 pairs of autosomes, PLUS 2 sex chromosomes: XX or XY.Boy or girl?

Homologous

Sister chromatids

Diploid human

Homologous chromosomes:- Same type of chromosome - Look identical but carry different information. -Each came from a different parent.

-Sister Chromatids: -Duplicate chromosomes that are still connected.

Diploid vs. Haploid cells:

2 sets of chromosomes

1 set of chromosomes

“2N” (human 2N=46)

“N” (human N=23)

Body Cells, Zygote

Gametes(egg&sperm)(Germ cells)

(‘Half’)

Apply: Write the diploid and haploid numbers for the following organisms:Organism Diploid (zygote,

body cells)Haploid (gametes)

HumansFruit flyDogBroccoliLizardShrimp

23464839789181836127254

Which of the following has, on average, larger cells – a sequoia tree, or a daisy plant? An elephant or an ant? Explain your answer.

1. Describe what is happening in the video clip.

2. What could be the purpose of this process? At least 2 ideas.

Altogether, cells divide in order to:

A. Enable growth while cells are kept small.

B. Replace old/damaged cells.C. For A-sexual Reproduction.

When new cells are made, the existing cells divide. Mitosis: the symmetrical movement of the duplicated chromosomes to the two daughter cells.

Products: Two diploid cells that are identical to the original cell.

We will demonstrate mitosis using yarn pieces

as chromosomes.

Mitosis 4 to 8 cells

Mitosis is Action (Animal)

Mitosis - LilyRoot Growing

Mitosis HeLa Cells

Mitosis Animation

STEPS of Mitosis: Yarn Simulation

Parts of the kit:Raise two chromosomes that are:A. Homologous to one another.B. Sister ChromatidsC. Choose the correct sheet.Process:Follow the process with your yarn pieces. Draw, Label, Describe.

* Bats have 72 chromosomes in all of their body cells.

* The first cell of the organism is made by joining egg and sperm.

1) How many chromosomes in a bat egg or a sperm cell? Explain.

2) Can cell division by mitosis (duplication of cells) produce egg or sperm? Explain.

46Zygote

Gametes

??

HUMANS!

46Zygote

Gametes

2323

HUMANS!

72Zygote

Gametes

??

BATS!

72Zygote

Gametes

3636

BATS!

2N

Mitosis: 1 Diploid to 2 Diploids:

2N

2NTetraploid

4N

Meiosis: 1 Diploid to 4 Haploids:

2N 4N 1N 1N1N 1N

DNA replication

DNA replication

Purpose:Mitosis: Make more identical

diploid cells.

Meiosis: a. Reduce chromosome number by half

b. Create genetic diversity

Mitosis animation

Meiosis Animation

animation

Yarn Kit: Meiosis (finally..)Using the four colors Show the split-split process.What do you get?

Drawing of mitosis and meiosis