Ths general biology unit 4 heredity cell cycle notes

1. BIOLOGY
Unit 4 Notes:
Cell Division
Basics &
The Cell Cycle

2. (1) What is Cell Division?
• Processes cells use to make copies of
themselves.
• Single Celled organisms can use it to
reproduce.
• Types of Division:
– Mitosis
– Meiosis

3. (2) Why Do Cells Divide?
• Grow
(make an organism larger and more
complex)
• Repair
(tissues that were damaged)
• Replace
(lost / broken down cells)
• Reproduce
(to make more cells or organisms)

5. (4) The Cell Cycle
• The cycle used to cells to prepare
for cell division:
–Makes copies of organelles.
–Doubles the size of the cell.
–Checks DNA for errors.
• Completes cell division after
preparation.

6. (5) Cell Cycle Diagram
G1 PHASE
S PHASE
G2 PHASE
M PHASE
G1
CkPt
G2
CkPt
Interphase:
G1
S
G2

7. (6) Cell Cycle Stages
• G1 Phase = 1st
Growth Phase
– Cell copies organelles and increases size.
• G1 Check Point Cell Makes sure cell is growing properly.
• S Phase = DNA Synthesis Phase
– Cell copies DNA
• G2 Phase = 2nd
Growth Phase
– Cell continues to copy organelles and increase size.
• G2 Check Point Cell makes sure DNA was copied
properly.
• M Phase = Mitosis or Meiosis Phase
– Cell actually divides.

9. (7) Cancer & The Cell Cycle
• If cells do not accurately check for
errors during the G1 or G2 check
points, defective or mutated cells
will begin dividing in the organism.
• Cancer:
–Malfunctioning cells which divide and
grow uncontrollably.