Mitosis

1
Mitosis Meiosis Chapter 2
How is the genetic material faithfully passed on
from one cell to the next (mitosis) and from one
generation to the next (meiosis)?
2
Prokaryotes vs. Eukaryotes
Prokaryotes
Eukaryotes

• Single cellular
• No organelles
• No nucleus
• Single circular DNA
• (naked)
• binary fission

• Single or multicellular
• Membrane bound
• organelles
• Nucleus
• Linear DNA (multiple)
• Mitosis meiosis

3
Typical Animal Cell
Fig. 2.1
4
Centromere location within chromosomes
Fig. 2.4
5
Human Karyotype
Locus for blood type gene
A
A
B
B
centromere
Fig. 2.5
Sister chromatids
from Mom
from Dad
Biparental inheritance Alleles Diploid number
(2n) Haploid number (n) Autosomes Sex chromosomes
(XX vs. XY) Chromatin vs. Chromosome
Homologous chromosomes during metaphase of mitosis
6
The Cell Cycle
Fig. 2.6
7
Stages of Mitosis
Also see Figs. 2.9 and 2.10
karyokinesis cytokinesis
Fig. 2.8
8
chromatids vs. centromeres
Assume 2n 4
Chromatids (chromosomes)
Centromeres
G1 phase After S phase After anaphase After
telophase (2 daughter cells)
4 4
8 4
8 8
4 4
9
Comparison of Mitosis to Meiosis
tetrad
Centromere splits
Centromere does not split
dyad
fertilization
Centromere splits
n n
2n
monad
Fig. 2.12
10
Meiotic Prophase I
1 2 3 4
Crossing over (homologous recomb.)
Homologous cs. synapse to form tetrads
maternal
paternal
tetrad
1 2, 3 4 sister chromatids 1 3, 2 4
nonsister chromaids
Pairs of sister chromatids separate
Metaphase I
Also see Fig. 2.13
chiasma
11
Meiosis (continued)
dyad (sister chromatids)
monad
Fig. 2.14
12
Nonhomologous chromosomes randomly align during
metaphase I.
OR
metaphase plate
gametes
This results in 4 types of gametes with equal
probability.
13
Consequences of Nondisjunction
Fig. 2.17
14
Spermatogenesis Oogenesis
Fig. 2.15
15
Summary of Mitosis Meiosis