P.37#1-19

April.4, 2013
Page 37, Questions Number 1-19

1.Describe the events in the cell cycle.
Ans: The cycle of cells's life is called the cell cycle. In cell cycle the cells grow and prepare for cell division.
The cell cycle can be divided into 2 phases: Interphase(Cell growth) and Mitosis(Cell division).
Interphase is when the cell is preparing for cell division which happens in 3 stages:
G1 phase: cell growth
S phase: DNA replication
G2 phase: preparation for mitosis
Mitosis is when the cells are dividing, and it happens in 4 stages: prophase,metaphase,anasphase ,telophase
and cytokinesis.

2.Compare mitosis in plants and animal cells.
Ans: In animal cells mitosis centrioles are involved and they help with moving choromosomes to 2 sides, which are absent in plant cells. And during cytokinesis, the cytoplasmic division process is different.In animal cells,ring of microfillaments form along the cell's equator causing the plasma membrance to pinch and separate. Where as in plant cells, vesicles from the golgi apparatus line up and form a new cell wall and membrane.

3.Describe the meaning of the term "apoptosis" and state its importance.
Ans: Apoptosis means the regulated and controlled death of cells. It's the death of cells that are no longer useful. It's important to remove cells that have lost their ability to function efficiently.

4.State one similarity and one difference between plant and animal mitosis.
Ans:

Similarities: In prophases, both chromosomes condense.
In metaphase, the chromosomes all align at the equator.
In anaphase, they move towards opposite poles
Differences: In prophase, animal cells have centrioles that organize spindles while plants don't.
In cytokinesis, animal cells contracts and split into 2, where in plant cells the cell wall is formed. Animal cell mitosis happens everywhere, where it only happens at the tips of roots,shoots in meristem tissues.
5.What is a cancer cell?
Ans: A cell that divides uncontrollably is called a cancer cell. Cancer cells develop when a change occurs in the cell that affects how that cell divides. When the DNA is changed, it's known as a mutation.

6.Explain how mitosis ensures genetic continuity.
Ans: In mitosis, the genetic information in the nucleus is divided into 2 equal parts. That way the daughter cells have the exact same DNA.

7.How does mitosis make the growth and repair of cells possible in an organism?
Ans: Mitosis is the essential process in cell division, and cell division provides new cells to replace cells that wear out or break down.

8.Why would you expect cells to spend the greatest percentage of their cycle in interphase?
Ans: Because during interphase, cells takes in nutrients, grows and conducts other cell function and prepares for cell division.

9. What happens to the chromosomes as a cell prepares to divide?
Ans: Chromosomes are connected to spindle fibres and is connected at its centromere, the chromosomes are later seperated into 2 parts.

10.How is a cancer cell different from a normal cell? Give 3 differences.
Ans: Cancer cells do not stop reproducing.
Cancer cells do not stick to other cells and behaves independently.
Cancer cells may move to another location of the body.

11.Describe the difference between mitosis in an animal cell and a plant cell.
Ans: Plants do not have centrioles just centrosomes. Animal cells have centrioles, so as to what produces the spindle fibers is one of the differences between plant and animal mitosis. The phases of mitosis and what goes on in each phase is the same except when it comes to how cytokinesis is accomplished. Plant cells divide the cytoplasmbetween the two new nuclei by forming a cell plate (new cell wall) between the nuclei. Animal cells accomplish this by forming a cleavage furrow which is a pinching in at the middle of the cell until two new cells have been formed with cytoplasm and organelles for each new nuclei.

12.Why must cell division be controlled or regulated for cells to remain healthy? Explain your answer.
Ans: Because each cell has to divide and die as it should in order. So the it can be health for the body. Just like how too many people can be bad for beathing in a crowded room.

13.A certain antibiotic affects cells by preventing the formation of spindle fibres. Explain how this drug would affect mitosis in cells.
Ans: Without the proper amount of spindle fibres, the cells wouldn't be able to go through mitosis as quickly and as organized. 

14.A drug used in chemotherapy causes chromosomes to move incorrectly during mitosis. As a result, the daughter cells that are produced havel either too much or too little genetic informattion. Predict why this treatment causes the caner cells to die.
Ans: Without the proper amount of chromosomes, the cells wouldn't be able to function as well. They might get other disease caused by the imbalance of chromosomes.

15.Identify the stage of mitosis shown in the photo below. Explain your thinking.
Ans: The stage of mitosis shown is anasphase  because during anasphase the chormatids s are pulled to opposite directions in the cell.

16.The nerve cell in our bodies rarely undergo mitosis. Use this information to explain why complete recovery from injuries to our system may not occur.
Ans: Because mitosis doesn't or rarely takes place, the tissues and organs are not able to be replaced.

17.Sunscreens protect your skin by blocking types of ultravalent radiatino. Explain why the canadian cancer socieyly advices canadians to apply sunscreen.
Ans: Ultravalent radiation can be harmful to our skin and damage our skin cells. Skin cancer are often resulted from the harm of the sun. Using sunscreen helps your skin recover and blocks some of the rays.

18.Suggest reasons why cancer researchers may be interested in using their learning about the processes of cell division, to develop new forms of cancer prevention and treatment.
Ans: By learning how mitosis works, we can understand how cells divide and grow. Which can help us better notice any thing that's wrong and repair or kill it before it divides and spreads.