AN INTRODUCTION TO MEIOSISGETTING TO KNOW…..

SOMATIC CELLS

BODY CELLS

GAMETES

DIPLOID

HAPLOID

HOMOLOGOUS

What was the purpose of MITOSIS?

Daughter Cells

Daughter Cells

How Do The Daughter Cells Compare To Each Other?

They are the SAME!!!

Where does the process of mitosis occur in your body?

1. Nose2. Toes3. Heart4. Liver

Daughter Cells

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NOSE, TOES, LIVER, AND HEART CELLS ARE ALSO KNOWN AS ….

Somatic Cells

What are Somatic Cells??Write it in your notes

What is another name for these somatic cells??

Body CellsWrite it in your notes

Which of the following is a somatic cell:

1. Liver 2. Cheek3. Kidney4. Spleen5. Muscle

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Which of the following is a body cell:

1. Liver 2. Cheek3. Kidney4. Spleen5. Muscle

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Do Ya Know?

How many chromosomes do you have in each of your body/somatic

cells?1. 232. 523. 264. 46

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Here are the somatic chromosome numbers for some other organisms…

Common Name Genus and Species Diploid ChromosomeNumber

Buffalo Bison bison 60Cat Felis catus 38

Cattle Bos taurus, B. indicus 60

Dog Canis familiaris 78Donkey E. asinus 62Goat Capra hircus 60Horse Equus caballus 64Human Homo sapiens 46Pig Sus scrofa 38Sheep Ovis aries 54

Based on this chart, does chromosome number have anything to do with animal complexity??

Common Name Genus and Species Diploid ChromosomeNumber

Buffalo Bison bison 60Cat Felis catus 38

Cattle Bos taurus, B. indicus 60

Dog Canis familiaris 78Donkey E. asinus 62Goat Capra hircus 60Horse Equus caballus 64Human Homo sapiens 46Pig Sus scrofa 38Sheep Ovis aries 54

NOPE!!!

Do All The Cells In Your Body Have 46

Chromosomes?????

NOPE!!!

Can You Think Of Some Cells In Your Body That DO NOT Have 46

Chromosomes?

Sperm

Egg

Sperm and Egg Cells Are Known As The Reproductive Cells Or…

THE GAMETES!!

The male gamete is the sperm cell.

The female gamete is the egg cell.

What would it be like if we used our somatic/body cells for reproductive purposes???

+

46 46 92 +

92

Do You Want Your Baby To Have 92 Chromosomes In A Somatic/Body

Cell???

NOPE!!!WHY NOT?

What do organisms “do” to make sure the chromosome number in the offspring

doesn’t double from generation to generation?

Organisms reduce the chromosome number in HALF.

If humans reduce their chromosome number by one half, how many chromosomes would you expect to find in a sperm or egg cell?

23

+

23 23 46 +

Here is what should happen.

Let’s See How You Are Doing

Which of the following cells is considered a somatic cell:

0%

0%

0%

0% 1. Sperm2. Egg3. Gamete4. Cheek cell

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Which of the following cells would you expect to have 23 chromosomes:

0%

0%

0%

0% 1. Cheek2. Liver3. Sperm 4. Female gamete

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A horse has 64 chromosomes in a somatic cell. How many chromosomes would you

expect to find in a gamete:

0%

0%

0%

0% 1. 1282. 643. 324. 16

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Name a somatic cell

Name a Gamete

A bird has 16 chromosomes in the female gamete. How many chromosomes would

you expect to find in a body cell.

20%

20%

20%

20%

20%

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1. 192. 463. 324. 85. 38

You’re almost finished with the vocabulary for today! The last word / concept we need to understand in the term…

HOMOLOGOUS CHROMOSOMES

This Is Called A Karyotype. WHAT ARE YOU LOOKING AT???

A KARYOTYPE SHOWS ALL 46 HUMAN CHROMOSOMES

WHERE DID YOU GET YOUR 46 CHROMOSOMES FROM????

23 FROM MOM

23 FROM DAD

STUDY THE KARYOTYPE. HOW ARE THE CHROMOSOMES GROUPED?

IN PAIRS!!!

THESE PAIRS OF CHROMOSOMES ARE CALLED….

HOMOLOGOUS PAIRS

What are HOMOLOGOUS

CHROMOSOMES??

LET’S FIND OUT!

HOMOLOGOUS CHROMOSOMES ARE CHROMOSOMES THAT ARE / HAVE THE…

SAME SIZE AND SHAPE

CENTROMERES IN THE SAME POSITION

GENES FOR THE SAME TRAITS IN THE SAME LOCATION

Hommie from MOM

Hommie from DAD

Centromere

Gene For Hair Color

Gene For Hair Color

Even though these HOMOLOGOUS CHROMOSOMES have the gene for hair color in the same location, does the actual GENE need to be the

same??

NOPE

Let’s Explore This Idea

Gene For Hair Color

Red Hair

Gene

Brown Hair

Gene

Cells that contain HOMOLOGOUS PAIRS are said to be….

DIPLOID CELLS

Your body cells / somatic cells are all diploid cells

You are looking at the nucleus of a cell. Is this cell DIPLOID?

How do you know?

You are looking at the nucleus of a cell. Is this cell Diploid?

How do you know?

This cell is considered HAPLOID.

What does it mean to be HAPLOID?

CELLS THAT DO NOT CONTAIN HOMOLOGOUS PAIRS

The symbol 2n is used to represent the diploid number of an organism. For example, the cell below has a diploid number of 6. You would write this …..

2n=6

The symbol n is used to represent the haploid number of an organism. For example, the cell below has a haploid number of 3. You would write this …..

n=3

What is the human diploid number

0%

0%

0%

0% 1. 2n=232. n=463. 2n=464. n=23

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What is the human haploid number

0%

0%

0%

0% 1. n=232. 2n=463. n=464. 2n=23

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Which of the following cells is/are diploid

0%

0%

0%

0% 1. Sperm2. Egg3. Gamete4. Cheek cell

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THE PROCESS THAT TAKES A DIPLOID CELL AND REDUCES THE CHROMOSOME NUMBER IN HALF TO FORM A HAPLOID CELL IS CALLED…

MEIOSIS

LET’S PRACTICE A FEW MORE BY

LOOKING AT THE HOMEWORK SHEET