1. I. The Reproduction of Cells

2. A. Why Do Cells Divide?
Repair- If cells are damaged, they must be replaced by cell division.
Replacement- If cells die, they must be replaced
Growth- If an organism is to increase in size, new cells must be added
Asexual Reproduction- one parent simply divides into two daughter cells

3. B. Introduction to Eukaryotic Chromosomes
Interphase, the eukaryotic nucleus contains Chromatin - long thin fibers of DNA and protein. The DNA can function when it is uncoiled but cannot be transported

4. DNA Packing

5. Introduction to Eukaryotic Chromosomes
2. For mitosis, the thin DNA fibers duplicate themselves and coil into structures called Chromosomes consisting of two highly coiled, exactly copied DNA strands called sister Chromatids which are held together by a structure called a centromere.
Centromere
Sister Chromatids

6. C. The Cell Cycle

7. 1. Interphase- time preparing for the next division
First Gap (G1) – Organelles are produced
Synthesis (S) – DNA replication occurs
Second Gap (G2)- cell grows to adult size

8. 2. Prophase Chromosomes shorten and thicken The nucleolus disappears
Centrioles move to opposite ends of the cell
Spindle fibers form
Prometaphase –nuclear membrane fragments and spindle fibers attach to chromsomes at the kinetochore

9. 3. Metaphase
Spindle fibers made of microtubules align the chromosomes in the middle of the metaphase plate

10. 4. Anaphase
Chromosomes are pulled by the spindle fibers to opposite ends of the cell

11. Mechanism of Chromosome Movement in Anaphase

12. 5. Telophase & Cytokinesis
Chromosomes become long and thin again
New Nuclear membrane and nucleolus form
Actin and Myosin fibers cause the cell membrane to pinch in

13. Mechanisms of Cytokinesis: The Division of the Cytoplasm
Arrows indicate the contraction of actin fibers separating the two daughter cells. Green indicates the remains of spindle fibers

14. 1. Animal Cell Cytokinesis
A cleavage furrow forms a shallow groove near the old metaphase plate.
A contractile ring of actin microfilaments form and begin contracting until the cell pinched in two.
The remains of the spindle breaks and phospholipid membranes fuse. The cells are separated.

15. 2. Plant Cytokinesis
Golgi vesicles containing cellulose, lignin and other building materials fuse near the old metaphase plate producing a cell plate
The plate grows laterally until they fuse with the cell wall separating the cells.

16. Cancer- Uncontrolled Growth of Cells
Tumors interfere with the normal functioning of the organ.
Malignant Tumor keeps getting larger and will spread
Benign Tumor tends to stop growing
Metastasis- Cancer cells break off and spread to other parts of the body

17. Warning Signs of Cancer
Change in bowel or bladder habits. Blood in feces or urine
A sore that doesn’t heal
Unusual bleeding or discharge
Thickening or lump in breast or elsewhere
Indigestion or difficulty in swallowing
Obvious change in a wart or mole
Nagging cough or hoarseness

18. Treatments Early diagnosis Chemotherapy Radiation Surgery Imaging
Biopsy
Chemotherapy
Radiation
Surgery

19. How Can We Protect Ourselves from Cancer?
Choose your parents carefully
Don’t get sunburned
Don’t smoke or use tobacco products
Get regular check ups
Protect yourself from STDs
Watch your weight
Eat high fiber foods and fresh fruits and vegetables

20. II. The Production of Human Gametes: Sperm and Egg
Human body cells contain 46 chromosomes. They are diploid they contain two sets of chromosomes (2n).
In order to produce a zygote (fertilized egg) with 46 chromosomes, the sperm and egg must contain 23 chromosomes.
To reduce the number of chromosomes in the gametes (sperm and egg cells) the body must carry on a process called Meiosis (My-oh-sis) or reduction division

21. D. Meiosis is similar to mitosis except:
The parent cell divides twice
Four cells are produced instead of two.
The daughter cells are haploid (n). they contain only one set of chromosomes. ½ the number of chromosomes as the parent cell.
Gametes or sex cells (sperm and egg) are produced in meiosis, while somatic cells (body cells) are produced in mitosis.

22. Crossing Over in Prophase I occurs only in Meiosis
Chiasma
Enzymes repair chromotids and sometimes new chromotids form
Synapsis: Homologous chromosomes pair and twist during prophase I
Chiasma: positions where the homologs cross and break

23. Crossing Over in Prophase I

24. Interphase Meiosis: Reduction Division Prophase I Interphase
Synapsis and crossing over
Interphase
Metaphase I
Telophase I
and Cytokinesis
Anaphase I
No 2nd
Interphase

25. Prophase II
Metaphase II
Anaphase II
Telophase II

26. SPERMATOGENESIS: Production of Human Sperm23 46 46 92 23
chromosomes
chromosomes 46 23
Interphase 23

27. Spermatogenesis

28. OOGENESIS: Production of Human Eggs23 46
Chromosomes
Chromosomes 46 92
Egg
Uneven cytokenesis
chromosomes
chromosomes 23
Polar Bodies 46 23
Interphase 23

29. Physical Evidence of Crossing Over Sordaria