Download The Cell Cycle and Mitosis

Cell Division in the Onion Root Tip
The Cell Cycle
• Cells grow and divide.
• As one cell enters Mitosis, two
cells exit which are exact
replicas or clones of the original
“parent” cell.
• Cells that no longer need to
divide exit the cell cycle in
G1(ex. neurons, muscle cells,
fat cells do this).
Purpose: to replenish dead or
dying cells, to allow an
organism to grow and develop
Interphase
• A cell spends the majority of
its lifetime in interphase.
• Cell grows and carries out
normal cell processes
• DNA replicates
• Prepares for cell division
•Plant cell
•Onion root tip
4 Stages of Mitosis: Plants & Animal Cells
Onion root tip
whitefish
•
•
Prophase:
Chromosomes
•
condense and form
visible bodies.
Nuclear
envelope breaks •
down.
Metaphase:
Chromosomes line •
up in the middle of
the cell.
•
Spindle fibers
attach to the
centromeres.
Telophase:
Anaphase:
• Nuclear envelope
Centromeres split.
reappears.
Cytokinesis
Sister chromatids
separate and are• The cytoplasm and
pulled to opposite all its contents
divide
sides of the cell.
Cell Cycle – onion root tip
Cell Cycle – onion root tip
Stages of mitosis (PMAT)
Conclusion Questions
1. Summarize the procedure for this lab.
2. The cells in the root of an onion are actively
dividing. How might the numbers of cells found in
this region differ from a different part of the plant?
3. What stage were the majority of the cells in the water
treated root tips?
4. What happens when cell division is interrupted?
•
1.
What process must take place before mitosis can begin?
5. What process must take place before mitosis can
begin?
Conclusion Questions
6. Why is mitosis important? Where does mitosis take
place?
7. Give an example of cells in your body that divide
slowly or do not divide at all.
8. What is cancer? How does cancer affect the rate of
mitosis?
9. How would a slide of cancerous cells look different
from this one?
10. What type of cells in your body do not divide by
mitosis?