Copy into Notes…
Aim # 4: How and why does meiosis
happen?
Meiosis: sexual reproduction process
that produces sex cells, each with
half the parent’s DNA
NameDateClassScience- Ms. Sowing
Class Work # 4
Directions: For each question, type your answers in the spaces provided.
Use your notes, the websites, and the table to help you:
Go to http://www.cellsalive.com/meiosis.htm
1.Write down 3 observations the meiosis interactive (3 things you see going
on during meiosis)
a. I saw 1 cell turn into 4
b. I saw chromosomes lining up and splitting
c. I saw the cells dividing 2 times
# Of cell divisions
# Of cells produced
# Of chromosomes in
each new cell
Types of cells
produced
Functions in body
Mitosis in Humans
1
2
46
Meiosis in Humans
2
4
23
All body cells except
sperm and egg cells
Growth, repair,
maintenance
Sperm and egg cells
only
Reproduction
2. How many cell divisions take place in meiosis?
-2 cell divisions take place in meiosis
3. What kind of cells does meiosis produce and for what function?
-Meiosis reproduces sex cells including sperm cells and egg cells, which are
used for making babies
4. How are mitosis and meiosis similar and different?
-They’re different because mitosis makes body cells and meiosis makes sex
cells. Mitosis and meiosis are similar because they are both cell division
Most of your growth occurs because your body added new cells. New
cells are produced as old cells go through mitosis. Just before mitosis
begins, the chromosomes double. Then, the chromosomes line up and
eventually pull apart so the cell divides into 2 identical cells with the same
exact DNA. In humans, body cells originally contain 46 chromosomes and
after mitosis is complete, each new human body cell contains 46
chromosomes. Likewise, fruit flies each have eight chromosomes in their
body cells and after mitosis is complete, each new fruit fly body cell has 8
chromosomes.
Sexual reproduction involves another type of cell division called
meiosis. Like mitosis, a cell splits in half to produce two daughter cells.
Unlike mitosis, in meiosis each daughter cell divides again. As a result, a cell
that undergoes meiosis can produce 4 sex cells, each with only half as many
chromosomes as a normal body cell. Sperm and egg cells are produced by
meiosis. When a sperm and egg join, they are able to produce a zygote that
has a full set of chromosomes- half from each parent. For example, a body
male’s body cell that originally has 46 chromosomes undergoes meiosis and
produces a sperm cell that has 23 chromosomes (half of 46). A woman’s
body cell after meiosis would produce an egg cell that has 23 chromosomes.
When a man and woman reproduce together, their baby would have body
cells that have 46 chromosomes (23 + 23). Similarly, fruit fly cells that
originally have 8 chromosomes would only have half as many- 4 chromosomes
after meiosis, but a fertilized fruit fly egg would have 8 chromosomes again.
5. A cell with 100 chromosomes undergoes mitosis. How many chromosomes
are in the new body cell after mitosis is over?
(a) 200
(b) 100
© 50
(d) 0
Copy into Notes…
Aim # 4: How and why does meiosis
happen?
My answer to # 5 is…
Meiosis: sexual reproduction process
that produces sex cells, each with
half the parent’s DNA
NameDateClassScience- Ms. Sowin
Class Work # 4
Directions: For each question, type your answers in the spaces provided.
Use your notes, the websites, and the table to help you:
Go to http://www.cellsalive.com/meiosis.htm
1.Write down 3 observations the meiosis interactive (3 things you see going
on during meiosis)
a.
b.
c.
# of cell divisions
# of cells produced
# of chromosomes in
each new cell
Types of cells
produced
Functions in body
Mitosis in Humans
1
2
46
Meiosis in Humans
2
4
23
All body cells except
sperm and egg cells
Growth, repair,
maintenance
Sperm and egg cells
only
reproduction
2. How many cell divisions take place in meiosis?
3. What kind of cells does meiosis produce and for what function?
4. How are mitosis and meiosis similar and different?
Most of your growth occurs because your body added new cells. New
cells are produced as old cells go through mitosis. Just before mitosis
begins, the chromosomes double. Then, the chromosomes line up and
eventually pull apart so the cell divides into 2 identical cells with the same
exact DNA. In humans, body cells originally contain 46 chromosomes and
after mitosis is complete, each new human body cell contains 46
chromosomes. Likewise, fruit flies each have eight chromosomes in their
body cells and after mitosis is complete, each new fruit fly body cell has 8
chromosomes.
Sexual reproduction involves another type of cell division called
meiosis. Like mitosis, a cell splits in half to produce two daughter cells.
Unlike mitosis, in meiosis each daughter cell divides again. As a result, a cell
that undergoes meiosis can produce 4 sex cells, each with only half as many
chromosomes as a normal body cell. Sperm and egg cells are produced by
meiosis. When a sperm and egg join, they are able to produce a zygote that
has a full set of chromosomes- half from each parent. For example, a body
male’s body cell that originally has 46 chromosomes undergoes meiosis and
produces a sperm cell that has 23 chromosomes (half of 46). A woman’s
body cell after meiosis would produce an egg cell that has 23 chromosomes.
When a man and woman reproduce together, their baby would have body
cells that have 46 chromosomes (23 + 23). Similarly, fruit fly cells that
originally have 8 chromosomes would only have half as many- 4 chromosomes
after meiosis, but a fertilized fruit fly egg would have 8 chromosomes again.
5. A cell with 100 chromosomes undergoes mitosis. How many chromosomes
are in the new body cell after mitosis is over?
(a) 200
(b) 100
© 50
(d) 0
My answer to # 5 is…..
6. Which step must occur before mitosis can begin?
(a) the cell’s DNA is copied
(b) The nuclear membrane breaks down
© the chromosomes separate
(d) the cell splits in half
My answer to # 6 is letter….
7. A cell with 40 chromosomes undergoes meiosis to produce an egg cell.
How many chromosomes are in the egg cell?
(a) 80
(b) 60
© 40
(d) 20
My answer to # 7 is letter…
8. Which cells are produced by meiosis?
(a) nerve cells
(b) sperm cells
© skin cells
(d) muscle cells
My answer to # 8 is letter…
9. All cells in the human body have 46 chromosomes, except sperm and egg
cells. Explain why…
REMEMBER TO SAVE YOUR WORK, AND THEN UPLOAD IT TO YOUR
WIKISPACE!!!
How to UPLOAD and SAVE documents on YOUR OWN WIKISPACE!
1.
2.
3.
4.
5.
6.
7.
8.
9.
Make sure you save your Aim 4 Class Work
Click on your class # and your name on the navigation bar on the right.
Click on the edit this page tab at the top.
Click on Green Tree to Insert Images and Files
Browse for the Aim 2 Class Work
Click Open
Press Upload
Double Click on the correct W document.
PRESS SAVE ON THE LOWER RIGHT SIDE OF YOUR PAGE!
6. Which step must occur before mitosis can begin?
(a) The cell’s DNA is copied
(b) The nuclear membrane breaks down
© The chromosomes separate
(d) The cell splits in half
My answer to # 6 is letter….
7. A cell with 40 chromosomes undergoes meiosis to produce an egg cell.
How many chromosomes are in the egg cell?
(a) 80
(b) 60
© 40
(d) 20
My answer to # 7 is letter…
8. Which cells are produced by meiosis?
(a) Nerve cells
(b) Sperm cells
© Skin cells
(d) Muscle cells
My answer to # 8 is letter…
9. All cells in the human body have 46 chromosomes, except sperm and egg
cells. Explain why…
REMEMBER TO SAVE YOUR WORK, AND THEN UPLOAD IT TO YOUR
WIKISPACE!!!
How to UPLOAD and SAVE documents on YOUR OWN WIKISPACE!
10. Make sure you save your Aim 4 Class Work
11. Click on your class # and your name on the navigation bar on the right.
12. Click on the edit this page tab at the top.
13. Click on Green Tree to Insert Images and Files
14. Browse for the Aim 2 Class Work
15. Click Open
16. Press Upload
17. Double Click on the correct W document.
18. PRESS SAVE ON THE LOWER RIGHT SIDE OF YOUR PAGE!