This document describes DNA, chromosomes, and the process of cell division. It defines key terms like DNA, genes, chromatin and chromosomes. It explains that eukaryotic cells undergo interphase before cell division. Cell division can be mitosis, which produces two diploid daughter cells, or meiosis, which produces four haploid cells. Meiosis has two rounds of division (Meiosis I and Meiosis II) to reduce the chromosome number. The stages of mitosis and each phase of meiosis are outlined, including what occurs in each phase.

1. I. GENERAL
A. REVIEW DNA
1. NUCLEOTIDE
2. DOUBLE HELIX – two nucleotide chains
C-G A-T

2. II. CELL CYCLE
A. GENERAL MITOSIS
1. DIAGRAM
G2 G1
S

3. 2. DEFINITIONS
a. DNA – A double helix molecule polymer with genetic
information.
b. GENE – A segment of DNA that codes for a specific
trait.
c. CHROMATIN – Uncondensed structures made of
DNA & proteins found in the nucleus with
genes on it.

4. d. CHROMOSOME – A condensed structure of DNA &
proteins found in the nucleus with genes on it.
Gene 1
Gene 2
Gene 3
1 chromosome
1 chromosome
1 chromatid = a single DNA molec.
2 chromatids = two DNA molec.

5. e. DIPLOID – An individual (cell, etc.) has 1 pair of
chromosomes with the same genes. The chromosomes
can have 1 or 2 chromatids each.
or
f. HAPLOID – An individual (cell, etc.) has 1 chromosome
with specific genes. The chromosome can have 1 or 2
chromatids each.
or

6. g. HOMOLOGOUS PAIR – two
chromosomes in a single cell that have
the same genes. Found in diploid
organisms.
Homologous pair where the Homologous pair where the
chromosomes of the pair have only chromosomes of the pair have
one chromatid. two chromatids.

7. B. PROKARYOTIC CELL DIVISION
BINARY FISSION

8. C. EUKARYOTIC CELL CYCLE
C1. INTERPHASE
– 90% cell life
– Where the cell spends most of its life

9. C2. CELL DIVISION (2 TYPES)
Mother cell Daughter cells
MITOSIS MEIOSIS
1. DIVIDE
2. # TIMES 1 2
3. WHERE (humans = all cells) (humans=gonads)
4. FUNCTION replace old cells sexual reproduction
growth
asexual reproduction

10. Interphase

11. MITOSIS
A. PHASES – diploid organism
prophase
metaphase
anaphase
telophase & cytokinesis

12. Prophase
1. Chromatin into chromosomes
2. Nuclear envelope disintegrates
3. Spindle fibers form near the nucleus and some attach
to kinetochores
4. Centrioles start to
move to opposite poles.

13. Metaphase
Chromosomes line up along the equator.

14. Anaphase
The spindle fibers are shortened at the kinetochore which
causes the chromatids to be pulled apart and moved to
opposite poles.

15. Telophase
Chromatids are at opposite poles, start to reform nuclear
membrane, spindle fibers start to disappear.

16. CYTOKINESIS
In animal cells the membrane pinches off to form 2 new
cells, reform chromatin and nucleus .

17. Overall

18. III. MEIOSIS - general
Two cell divisions where the resulting
daughter cells have ½ the number of
chromosomes as the originals.
23
23
MI MII 23
46
23
23
23

19. Prophase I of Meiosis I
Nuclear membrane starts to disintegrate.
Chromatin to chromosomes. Centrioles move. Form
spindle fibers.
Homologous Pairs form chiasma where can get
crossing-over (exchange of genetic material) =
recombination

20. Metaphase I of Meiosis I
Homologous pairs line up along the equator.
Independent Assortment – the chromosomes arrange
themselves independent of the other homologous pairs.
Type of recombination.

21. Anaphase I of Meiosis I
The spindle fibers shorten and pull apart the chromosomes
of the homologous pairs.

22. Telophase I of Meiosis I
The chromosomes reach opposite poles and start to form
nuclear membrane and disintegrate spindle fibers.

23. Cytokinesisand start to form
The chromosomes reach opposite poles
nuclear membrane and disintegrate spindle fibers.
Divide cell contents.
The two new cells each contain ½ the number of
chromosomes as the original cell (each chromosome
has two chromatids).

24. Prophase of Meiosis II
Re-condense chromosomes if they uncondensed and
replicate the centrioles.
Spindle fibers form and centrioles move to opposite poles.

25. Metaphase of Meiosis II
Chromosomes line up along equator.
Spindle fibers attached.

26. Anaphase of Meiosis II
Spindle fibers exert force to pull chromatids apart.

27. Telophase of Meiosis II
Chromosomes reach the opposite poles and start to reform
nuclear membranes.

28. Cytokinesis
Split the cell contents so that end up with four haploid cells.