AN INTRODUCTION TO MEIOSIS
GETTING TO KNOW…..
SOMATIC CELLS
BODY CELLS
GAMETES
DIPLOID
HAPLOID
HOMOLOGOUS
What was the
purpose of MITOSIS?
Daughter
Cells
How Do The Daughter Cells
Compare To Each Other?
Daughter
Cells
They are the SAME!!!
Where does the process of mitosis
occur in your body?
1.
2.
3.
4.
Nose
Toes
Heart
Liver
Daughter
Cells
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 Cells
Write it in your notes
Which of the following is a somatic
cell:
1.
2.
3.
4.
5.
Liver
Cheek
Kidney
Spleen
Muscle
Which of the following is a body cell:
1.
2.
3.
4.
5.
Liver
Cheek
Kidney
Spleen
Muscle
Do Ya
Know?
How many chromosomes do you
have in each of your body/somatic
cells?
1.
2.
3.
4.
23
52
26
46
Here are the somatic chromosome
numbers for some other organisms…
Common Name
Genus and Species
Diploid Chromosome
Number
Buffalo
Bison bison
60
Cat
Felis catus
38
Cattle
Bos taurus, B.
indicus
60
Dog
Canis familiaris
78
Donkey
E. asinus
62
Goat
Capra hircus
60
Horse
Equus caballus
64
Human
Homo sapiens
46
Pig
Sus scrofa
38
Sheep
Ovis aries
54
Based on this chart, does chromosome number
have anything to do with animal complexity??
Common Name
Genus and Species
Diploid Chromosome
Number
Buffalo
Bison bison
60
Cat
Felis catus
38
Cattle
Bos taurus, B.
indicus
60
Dog
Canis familiaris
78
Donkey
E. asinus
62
Goat
Capra hircus
60
Horse
Equus caballus
64
Human
Homo sapiens
46
Pig
Sus scrofa
38
Sheep
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
Do You Want Your Baby To Have 92
Chromosomes In A Somatic/Body
Cell???
92
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
Here is what should happen.
+
23
+
23
46
Let’s See How
You Are Doing
Which of the following cells is
considered a somatic cell:
1.
2.
3.
4.
0%
0%
0%
0%
Sperm
Egg
Gamete
Cheek cell
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Which of the following cells would you
expect to have 23 chromosomes:
1.
2.
3.
4.
0%
0%
0%
0%
Cheek
Liver
Sperm
Female gamete
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
A horse has 64 chromosomes in a somatic
cell. How many chromosomes would you
expect to find in a gamete:
0%
1. 128
0%
2. 64
3. 32
0%
4. 16
0%
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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.
1.
2.
3.
4.
5.
20%
20%
20%
20%
20%
19
46
32
8
38
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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
Gene For Hair
Color
Centromere
Hommie
from MOM
Hommie
from DAD
Even though these HOMOLOGOUS
CHROMOSOMES have the gene for hair color in the
same location, does the actual GENE need to be the
same??
Gene For Hair
Color
NOPE
Let’s Explore This Idea
Red
Hair
Gene
Brown
Hair
Gene
Gene For Hair
Color
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
1.
2.
3.
4.
0%
0%
0%
0%
2n=23
n=46
2n=46
n=23
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
What is the human haploid number
1.
2.
3.
4.
0%
0%
0%
0%
n=23
2n=46
n=46
2n=23
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Which of the following cells is/are
diploid
1.
2.
3.
4.
0%
0%
0%
0%
Sperm
Egg
Gamete
Cheek cell
1
2
3
4
5
21
22
23
24
25
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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