This document discusses mitosis and the cell cycle. It begins by stating the objectives of understanding cell growth problems, how cell division solves them, and the phases of mitosis. It then provides background on cell theory and reviews important cell structures. It explains that cells grow in size during interphase and divide during mitosis and cytokinesis. The four phases of mitosis - prophase, metaphase, anaphase and telophase - are described. The document notes that cell division is regulated to control growth but cancer occurs when cells divide uncontrollably.

1. Mitosis

2. Objectives:
 Understand why cell growth can cause problems for a cell.
 Understand why cell division solves the problems of cell growth.
 Understand what happens in the phases of mitosis.
 Understand how the cell cycle is regulated and what goes wrong if it is
not.

3. Cell Theory
1. All organisms (living things) are composed of
one or more cells.
2. Cells are the smallest living things.
3. New cells are produced from existing cells.

4. Cells Review:
 What are some important organelles in the cell? What is their function?

5. Atom
Molecule
Macromolecule
Organelle
Cell
Tissue
Organ
Organ System
Organism
Cellular Organization

6. Needs of a Cell?

7. Cell Size Limitations
Ratio of surface area to volume
Surface area is the area covered by the cell
membrane.
Volume is the space taken up by the inner contents
of the cell
Cells with a higher surface area to volume ratio can
sustain themselves for easily.

8. Surface Area to Volume Ratio

9. Ratio of Surface Area to Volume
1. Smaller cells can transport nutrients and wastes more
easily.
Diffusion is inefficient over longer distances
Cytoskeleton is less efficient when cells are larger
2. Cellular communication with DNA is more efficient in
smaller cells.
The larger a cell becomes, the more demands the cell
places on DNA.

10. Cell Cycle
Stage Description
Number
of Cells
Interphase
The cell grows in size, performs normal
functions, and copies its DNA. one cell
Mitosis
The cell nucleus divides, and the
chromosomes separate into the two
nuclei.
one cell
Cytokinesis
The cytoplasm of the cell divides,
forming two daughter cells.
two cells

11. Speed of Cell Division
The time it takes for a cell to complete the cell
cycle depends on the type of cell.
A typical animal cell takes 12-24 hours
Some cells take 8 minutes
Other cells can take as long as a year

12. Cell Cycle
Cell Growth
DNA
replication
Preparation
for mitosis
Mitosis
and
Cytokinesis

13. Chromosomes
 Carries the genetic information that is passed on from
one generation of cells to the next.
Made up of DNA
Every organism has a specific number of chromosomes
Human cells have 46 chromosomes
Fruit flies have 8 chromosomes
Carrot cells have 18 chromosomes

14. Chromatid
 Before cell division, each chromosome makes a copy.
Chromatid
Identical pair of chromosomes
Identical “sisters”
Centromere

15. Chromosome Terminology
Diploid – have two of each chromosome (di = two),
or one full set
Haploid – have half (hap = half) a chromosome set,
or one from each pair

16. Mitosis
A cell nucleus divides to eventually produce two
new cells.
A cell is dividing by mitosis if:
1. Results in two daughter cells.
2. Daughter cells are diploid.
3. Occurs in somatic cells.

17. Mitosis Phases
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

18. 1. Prophase (longest phase)
 Chromatin organizes into
chromosomes
 Centrioles separate to form a spindle.
 Nuclear membrane breaks down

19. 2. Metaphase
 Chromosomes connect to
spindle fibers at its centromere
 Chromosomes line up across
the center of the cell

20. 3. Anaphase
 Sister chromatids separate into
individual chromosomes
 Chromosomes are moved apart

21. 4. Telophase
 Chromosomes gather at opposite ends
of the cell
 Nuclear membrane re-forms
 Nucleolus reappears

22. Cytokinesis
 Cytoplasm pinches in half.
 Each daughter cell has an identical set of
chromosomes.
Plant cell: cell plate forms to divide daughter cells

24. Cell Growth
 Most cells will continue to grow and divide
until they come into contact with other cells.
 Different types of proteins have been found
to help regulate the timing of the cell cycle.
Some are inside the cell and some are outside

25. Uncontrolled Cell Growth
 Cancer cells do NOT respond to the signals
that regulate the growth of most cells.
Therefore, they divide uncontrollably and form
masses of cells called tumors.
This can damage surrounding tissues
Cancer cells break off the tumor and can
spread throughout the body.