1. Chapter 5 : Cell Growth and Division

2. KEY CONCEPT - Section 5.1 Cells have distinct phases of growth, reproduction, and normal functions.

3. The cell cycle is a regular pattern of growth, DNA replication, and cell division.

4. The main stages of the cell cycle are :
Gap 1 (G1): cell growth and normal functions
DNA synthesis (S): copies DNA
Gap 2 (G2): additional growth
Mitosis (M): division of the cell nucleus (mitosis)
cytokinesis : division of the cell cytoplasm
Mitosis occurs only if the cell is large enough and the DNA undamaged.

5. The rate of cell division varies with the need for those types of cells.

6. Chromosomes are formed at the start of mitosis.
KEY CONCEPT - Section 5.2 Cells divide during mitosis and cytokinesis.
Chromosomes are formed at the start of mitosis.
DNA becomes supercoiled - easier to organize
DNA double helix
DNA and histones
Chromatin
Supercoiled DNA

7. DNA plus proteins is called chromatin.
chromatid
centromere
telomere
One half of a duplicated chromosome is a chromatid.
Sister chromatids are held together at the centromere.
Telomeres protect DNA and do
not include genes.
Condensed, duplicated chromosome

8. cells spend 90% of the cell cycle in interphase
Parent cell
centrioles
spindle fibers
centrosome
nucleus with
DNA
cell grows, prepares to divide
DNA is duplicated

9. Mitosis divides the cell’s nucleus in four steps:
PROPHASE : chromosomes condense and spindle fibers form.

10. METAPHASE : chromosomes line up in the middle of the cell.

11. ANAPHASE : sister chromatids separate to opposite sides of the cell.

12. TELOPHASE : the new nuclei form and chromosomes begin to uncoil.

13. Cytokinesis - splitting of cytoplasm and organelles between two new cells
In animal cells, the membrane pinches closed between two cells
In plant cells, a cell plate forms new cell walls between the two new cells

14. Internal and external factors regulate cell division.
KEY CONCEPT - Section 5.3 Cell cycle regulation is necessary for healthy growth.
Internal and external factors regulate cell division.
External factors include physical and chemical signals.
Growth factors are proteins that stimulate cell division.
Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

15. Cell growth is balanced by cell death in healthy organisms
Apoptosis = programmed cell death.
a normal feature of healthy organisms
caused by a cell’s production of self-destructive enzymes
occurs in development of infants
webbed fingers

16. Cell division is uncontrolled in cancer - “immortal cells”
Cancer cells form disorganized clumps called tumors.
Benign tumors remain clustered and can be removed.
Malignant tumors metastasize, or break away, and can form more tumors.
cancer cell
bloodstream
normal cell

17. Cancer cells do not carry out necessary functions.
Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

18. Carcinogens are substances known to promote cancer.
- examples : UV radiation, tobacco, asbestos, exposure to environmental poisons
Standard cancer treatments typically kill both cancerous and healthy cells.

19. Binary fission is similar in function to mitosis.
KEY CONCEPT - Section 5.4 Many organisms reproduce by cell division.
Binary fission is similar in function to mitosis.
Asexual reproduction is the creation of offspring from a single parent.
Binary fission produces two daughter cells genetically identical to the parent cell.
method of reproduction in
prokaryotes
parent cell
DNA
duplicates
cell begins
to divide
daughter
cells

20. Specialized cells perform specific functions.
KEY CONCEPT - Section 5.5 Cells work together to carry out complex functions.
Specialized cells perform specific functions.
Cells develop into their mature forms through the process of cell differentiation.
Cells differ because different combinations of genes are expressed.
A cell’s location in an embryo helps determine how it will differentiate.
Outer: skin cells
Middle: bone cells
Inner: intestines

21. Stem cells are unique body cells.
Stem cells have the ability to
divide and renew themselves
remain undifferentiated in form - they can “turn into” other types of cells
develop into a variety of specialized cell types