1. Chromosomes and Cell Reproduction
Roughly 25 million new cells are made per second in the human body
Cell reproduction is also called cell division
Two types of division for two types of cells
Prokaryotes
Binary fission: asexual reproduction making identical offspring.
Cell basically just splits in two

2. Two stages of binary fission
Stage 1: DNA is copied
Stage 2: new membrane forms, squeezes cell into two new cells and a new cell wall forms
Very quick, and happens usually very often

3. Eukaryotes “you” carry oats
Much more complex (this chapter is mostly about this, the following is an overview)
DNA replicates
DNA separates
DNA moved to opp. Sides
Cytoplasm divides
Two new identical cells are formed.

4. Important terms:
Gene: a segment of DNA that codes for a particular trait
Chromosomes: Basically the visible DNA.
Chromatids: two exact copies of DNA
Centromere: where the two chromatids are connected
Homologous Chromosomes: chromosomes that are similar
Diploid: (2n) two sets of chromosomes
Haploid: (n) one of the copied chromosomes
Zygote: fertilized egg.

5. Orangutans: 48 chromosomes.

6. The Sex Chromosomes
In humans there are 23 pairs of chromosomes, 22 are somatic or autosomal, meaning they are not directly involved is gender (sex).
The other pair are the sex chromosomes, or the ones that determine gender (and other stuff)the
Everyone typically has two: X or a Y
Therefore females are XX and Males are XY
Karyotype: is a photo of the chromosomes in a dividing cell. Computer technology and great microscopes help enable us to see this.

8. Mutations: changes in the DNA structure.
Four types
Deletion: one or more is removed
Duplication: one or more is copied excessively
Inversion: in reverse order as original
Translocation: attaches somewhere else

10. How do little elephants grow up to be BIG elephants?

11. Why do animals shed their skin?

12. The process of asexual reproduction begins after a sperm fertilizes an egg.

13. Three reasons why cells reproduce by asexual reproduction 1. Growth 2
Three reasons why cells reproduce by asexual reproduction 1. Growth 2. Repair Replacement
Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.
Cell that reproduce by asexual reproduction reproduce constantly.

14. The Cell Cycle
Includes the life cycle of the cell and is divided into several parts
Interphase: the growth phase, most cells are in this phase, included in this is:
G1 or first growth phase
S or synthesis phase
G2 or second growth phase
Mitosis follows
Cytokinesis ends the cycle.

16. G1: rapid growth, cells found in this stage the majority of their lives. Most muscle and nerve cells never divide, so they never leave this stage. First check point
S: DNA is copied, end each chrom. Now has an identical match, called sister chromatids. Second check point.
G2: preparations are made for nucleus to divide, microtubules are arranged.
Mitosis: next several slides (another check point at the end of mitosis).
Cytokinesis: cytoplasm division, different in plants and animals.

17. Animated Mitosis Cycle
Interphase
Prophase
Metaphase
Anaphase
Telophase & Cytokinesis

18. Interphase occurs before mitosis begins
Chromosomes are _________ (# doubles)
Chromatin becomes visible as DNA coils tightly together forming chromosomes. Copies are called sister chromatids (but have not come together yet)
CELL MEMBRANE
Nucleus
Cytoplasm

19. Interphase Plant Cell Animal Cell
Photographs from:

20. Prophase 1st step in Mitosis
Nuclear membrane disappears
Chromatids are visible and joined at the centromere
Start to move towards middle of cell

21. Prophase Plant Cell Animal Cell Spindle fibers Centrioles
Photographs from:

22. Metaphase 2nd step in Mitosis
______________(or pairs of chromosomes) attach to the spindle fibers.
Moved to the “middle”

23. Metaphase Plant Cell Animal Cell
Photographs from:

24. Anaphase 3rd step in Mitosis
Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

25. Anaphase Plant Cell Animal Cell
Photographs from:

26. Telophase 4th step in Mitosis
Nuclear envelope starts to reappear
Chromosomes are at opp. Sides
Start to uncoil
Spindle fibers break down

27. Telophase Plant Cell Animal Cell
Photographs from:

28. Cytokinesis occurs after mitosis
Animals: cell begins to “pinch” in middle: cleavage
Plants: cell wall begins to form in the center, working outward, until it connects the two sides.

29. Animal Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

30. Plant Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

31. IPMATC REMEMBER! Interphase Prophase Metaphase Anaphase Telophase
Cytokinesis
IPMATC
A mnemonic to help remember the stages of mitosis.
I Pray More At The Church

32. Cell Cycle

33. - Cell Division
The Cell Cycle 33

34. Mitosis Animation