1. Mitosis and
Asexual Reproduction

2. Cell Cycle Mitosis Cytokinesis
Period of time from one division to the next
Unicellular division results in formation of new individuals of the species
Cell Cycle
Multicellular division results in replacement of old or damaged cells
Process by which the nucleus divides while maintaining number of chromosomes
Mitosis
Cytokinesis
Division of the cytoplasm
Asexual Reproduction
Reproduction that only involves one parent so therefore no special reproductive organs are needed

3. Interphase Prophase Metaphase Anaphase Telophase
Nuclear DNA wound around proteins known as histones
Chromatin
Chromosomes
Condensed rolls of chromatin that are able to be seen during mitosis (rod-like structures)
There are 5 phases in MITOSIS
Interphase
Prophase
Metaphase
Anaphase
Telophase

4. Draw Interphase Interphase Known as “resting phase”
Cells grow in size by producing more nucleic acids, proteins, and cellular organelles
Chromosomes make copies of themselves, but they can’t be
seen
Nucleus of the cell is contained within the nuclear envelope
Centrioles are present and duplicate themselves
Draw Interphase

5. Draw a Chromosome One Double Chromosome Prophase
Double chromosomes become visible - Chromatid
Chromosomes are 2 sister chromatids connected by a centromere
Draw a Chromosome
Centromere
Sister Chromatids
One
Double
Chromosome

6. Draw Prophase DON’T DRAW
At the beginning, centrioles move to opposite poles
Aster (star shaped fibers) extend = microtubules
Spindle fibers attach (to centromere to pull away chromatids to opposite sides of the cell)
By the end, the nuclear envelope and nucleus have
disappeared
Draw Prophase
EARLY
LATE
DON’T DRAW

7. Draw Metaphase Metaphase
Centromeres line up on the equator (middle= metaphase plate)
By the end, the centromeres divide and pull the daughter chromosomes to opposite sides of the cell
Half of each chromosome goes to the opposite side of the cell
Draw Metaphase

8. Draw Anaphase Anaphase
Daughter chromosomes move to opposite sides of cell
(poles)
Movement is accomplished by the microtubules
Movement occurs by shortening of the microtubules
Draw Anaphase

9. Draw Telophase Telophase
Chromosomes uncoil and return to previous shape (threadlike)
Nuclear membrane and nuclei reform
Draw Telophase
NOTE: Cytokinesis begins during late anaphase and finishes during telophase

10. Mitosis in Plants Same as mitosis in animals except:
Plants have no centrioles – spindle fibers take their place
Asters do not form
Cell wall does not pinch because it is too rigid
Cell plate divides the cell into two

11. Asexual Reproduction Occurs only through the process of mitosis
Each offspring has the same genetic information
Where can asexual reproduction be found?
BACTERIA
YEAST
PLANTS

12. Meiosis Sexual Reproduction

13. SEXUAL REPRODUCTION
Sex cells formed by meiosis
Requires 2 parents
Offspring not identical
Meiosis
The process that results in the formation of gametes
Gametes
Sex cells, egg or sperm, which have haploid chromosomes
Haploid
Haploid means HALF, as in the number of chromosomes,
written as n

14. The union of an egg and a sperm
Fertilization n 2n
The union of an egg and a sperm
Zygote
The cell that is formed when the egg becomes fertilized by the sperm. This results in a full set of chromosomes.
Somatic Cells
All body cells except for sex cells that have diploid chromosomes
Diploid
Diploid means they have chromosome found in pairs,
written as 2n

15. Homologous Chromosomes
Similar chromosomes that are found in pairs. The paired chromosomes come from the mother and father.
* Human body cells have 46 chromosomes each
* Human body cells have 23 homologous pairs
Meiosis and Fertilization
Important for survival of many species, because these processes result in genetic variation of offspring.
Meiosis
A kind of cell division that results in gametes (sex cells) with half the number of chromosomes.

16. A. Gametes do not have homologous pairs, but instead they have only half the chromosomes from each pair. Gametes are referred to as haploid (n).
B. When fertilization occurs, the zygote will have a normal number of chromosomes (2n).
C. In meiosis, specialized cells divide 2 times producing daughter cells.

17. Meiosis Parent cell – chromosome pair Chromosomes copied
1st division - pairs split
2nd division – produces 4 gamete cells with ½ the original no. of chromosomes

18. Mitosis vs. Meiosis