1. CHAPTER 8 The Cellular Basis of Reproduction and Inheritance

2. Biology is the only subject in which multiplication is the same thing as division…

3. CONNECTIONS BETWEEN CELL DIVISION AND REPRODUCTION
Cell division is at the heart of the reproduction of cells and organisms
Organisms can reproduce sexually or asexually

4. Like begets like, more or less
Some organisms make exact copies of themselves, asexual reproduction
Other organisms make similar copies of themselves in a more complex process,sexual reproduction

5. Prokaryotes reproduce by binary fission
Prokaryotic cells divide asexually
These cells possess a single chromosome, containing genes
The chromosome is replicated
The cell then divides into two cells, a process called binary fission
Duplication of chromosome and separation of copies
Continued growth of the cell and movement of copies
Division into two cells

6. THE EUKARYOTIC CELL CYCLE AND MITOSIS
A eukaryotic cell has many more genes than a prokaryotic cell
The genes are grouped into multiple chromosomes, found in the nucleus
The chromosomes of this plant cell are stained dark purple

7. The large, complex chromosomes of eukaryotes duplicate with each cell division
Sister chromatids
Chromosomes contain a very long DNA molecule with thousands of genes
Individual chromosomes are only visible during cell division
They are packaged as chromatin
Before a cell starts dividing, the chromosomes are duplicated
This process produces sister chromatids
Centromere

8. double-stranded human chromosomes
ready for mitosis

9. The large, complex chromosomes of eukaryotes duplicate with each cell division
When the cell divides, the sister chromatids separate
Two daughter cells are produced
Each has a complete and identical set of chromosomes
Chromosome duplication
Sister chromatids
Chromosome distribution to daughter cells

10. The Cell Cycle
The cell cycle is the sequence of growth and division of a cell. Duration varies with cell type
The cell cycle consists of two major phases:
Interphase, where chromosomes duplicate and cell parts are made
The mitotic phase, when cell division occurs
Interphase

11. Interphase: A Busy Time
Interphase, the busiest phase of the cell cycle, is divided into three parts.
Interphase
DNA synthesis and replication
Rapid growth and metabolic activity
cell prepares for division

12. Cell division is a continuum of dynamic changes
Eukaryotic cell division consists of two stages:
Mitosis~ process during which duplicated chromosomes are separated into 2 nuclei
Cytokinesis ~ entire cell divides into 2 daughter cells

13. MITOSIS: Making New Cells Making New DNA

14. Where it all began…
You started as a cell smaller than a period at the end of a sentence…

15. Getting from there to here…
Going from egg to baby….
the original fertilized egg has to divide…
and divide…

16. Why do cells divide… One-celled organisms Multi-celled organisms
for reproduction
asexual reproduction (clones)
Multi-celled organisms
for growth & development
from fertilized egg to adult
for repair & replacement
replace cells that die from normal wear & tear or from injury
amoeba
starfish
Unicellular organisms
Cell division = reproduction
Reproduces entire organism& increase population
Multicellular organisms
Cell division provides for growth & development in a multicellular organism that begins as a fertilized egg
Also use cell division to repair & renew cells that die from normal wear & tear or accidents

17. Mitosis

18. Mitosis

19. Mitosis in whitefish blastula

20. Mitosis in plant cell

21. onion root tip

22. 8.7 Cytokinesis differs for plant and animal cells
In animals, cytokinesis occurs by cleavage
This process pinches the cell apart
In plants, a membranous cell plate splits the cell in two

23. Overview of mitosis Please Make Another Two Cells I.P.M.A.T.C.
interphase
prophase
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase

24. New “daughter” cells Get 2 exact copies of original cells same DNA
“clones”

25. 8.8 Anchorage, cell density, and chemical growth factors affect cell division
In laboratory cultures, most normal cells divide only when attached to a surface
They are anchorage dependent
Cells continue dividing until they touch one another
This is called density-dependent inhibition
Growth factors are proteins secreted by cells that stimulate other cells to divide

26. 8.9 Growth factors signal the cell cycle control system
Proteins called cyclins within the cell control the cell cycle
Signals affecting critical checkpoints determine whether the cell will go through a complete cycle and divide
The binding of growth factors to specific receptors on the plasma membrane is usually necessary for cell division

27. 8.10 Connection: Growing out of control, cancer cells produce malignant tumors
Cancer cells have abnormal cell cycles
They divide excessively and can form abnormal masses called tumors
Radiation and chemotherapy are effective as cancer treatments because they interfere with cell division

28. Cancer: breast cancer cell & mammogram

29. Traditional treatments for cancers
Treatments target rapidly dividing cells
high-energy radiation
kills rapidly dividing cells
chemotherapy
stop DNA replication
stop mitosis & cytokinesis
stop blood vessel growth

30. New “miracle drugs”
Drugs targeting proteins (enzymes) found only in cancer cells
Gleevec
treatment for adult leukemia (CML) & stomach cancer (GIST)
1st successful drug targeting only cancer cells
Proof of Principle: you can treat cancer by targeting cancer-specific proteins.
GIST = gastrointestinal stromal tumors, which affect as many as 5,000 people in the United States
CML = chronic myelogenous leukemia, adult leukemia, which affect as many as 8,000 people in the United States
Fastest FDA approval — 2.5 months
without Gleevec
with Gleevec
Novartes

31. Cancer: A mistake in the Cell Cycle
Currently, scientists consider cancer to be a result of changes in one or more of the genes that produce substances that are involved in controlling the cell cycle.
Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients

32. Cancer: A mistake in the Cell Cycle
In later stages, cancer cells enter the circulatory system and spread throughout the body, a process called metastasis, forming new tumors that disrupt the function of organs, organ systems, and ultimately, the organism.

33. The causes of cancer
The causes of cancer are difficult to pinpoint because both genetic and environmental factors are involved.
Environmental factors, such as cigarette smoke, air and water pollution, and exposure to ultraviolet radiation from the sun, are all known to damage the genes that control the cell cycle.
Cancer may also be caused by viral infections that damage the genes.

34. Cancer prevention
Physicians and dietary experts agree that diets low in fat and high in fiber content can reduce the risk of many kinds of cancer.
Vitamins and minerals may also help prevent cancer.
In addition to diet, other healthy choices such as daily exercise and not using tobacco also are known to reduce the risk of cancer.