CO 04

1
CO 04
The chromosome theory of inheritance
2
Fig. 4.5
Metaphase chromosome can be classified by
centromere position
3
Fig. 4.6
Karyotype of a human male
Metaphase chromosomes
4
Table 4.1
Y is necessary for male fertility
Mentally retarded
Human Y makes the difference. Drosophila ratio
of number of X chromosome to copy number of
autosome
5
Fig. 4.7
Mitosis Ensures that Every Cell in an Organism
Carries the Same chromosomes
6
Fig. 4.8
7
Fig. 4.9
8
Fig. 4.10
Syncytium a cell with two or more nuclei
Red chromosome Green spindle fibers
9
Fig. 4.11
Checkpoints help regulate the cell cycle
10
Fig. 4.12
Meiosis
Reduction division
Equational division
11
Fig. 4.13a
Prophase I in meiosis
Chromosome condensation
Pairing of homologous chromosomes
Reciprocal exchange of the genetic information
tetrad
12
Fig. 4.13d
13
Fig. 4.13b
Meiosis I metaphase
Chiasma ensures proper segregation of homologous
chromosomes
14
Fig. 4.13e
Meiosis I
interphase
15
Fig. 4.13c
Meiosis II
16
Fig. 4.13f
Meiosis II
17
Segregation during meiosis
Segregation error trisomies
trisomy 21 Down syndrome
extra X Klinefeller
male Nondisjunction
18
Fig. 4.16
Hybrid animal mule
Male donkey 31 autosomes Female horse32
autosomes
19
Fig. 4.17
Meiosis contributes to genetic diversity
213107
20
Gametogenesis
(gamete formation)
mitosis
Germ cells (embryonic germ cells)
Primary cells (diploid)
differentiation
meiosis
gametes
21
Oogenesis asymmetric meiotic division
500,000
Primary oocytes
at metaphase II
Diploid germ cells (oogonia)
diplotene
22
Spermatogenesis symmetric meiotic division
Male germ cells
mitosis
Meiosis I
Meiosis II
20 days
20 days
20 days
23
Validation of chromosome theory of inheritance

• The chromosome theory
• correlates Mendels law
• with chromosome behavior
• during meiosis.
• 2. The transmission of particular chromosomes
  coincides with the transmission of specific traits

24
Fig. 4.20
X-linkage explains the inheritance of alleles of
the white gene
Criss-cross inheritance The male inherit their
eye color from their mothers, and vice vesa.
25
Fig. 4.21
Nondisjunction
1/2000
Cytologically with two X chromosomes
1/2000, W male w female
26
Fig. 4.22
Sex chromosome-linked disease
Red-green color blindness (recessive)
8 man, 0.44 women
Maternal grandfatehr
50 grandson
27
Fig. 4.23

• Five properties of X-linked recessive disease
• More male than female.
• Never pass form father to son (son only get Y
  from father).
• Maternal father pass the disease to grandson.
• The disease often skip one generation from
  grandfather through a carrier daughter.
• With the rare affected female, all her son will
  be affected and all her daughter
• will be carriers.

28
??????????
3. 50 of son and daughter
2. Father to daughter
1. More female than male have the disease
29
Sex-limited trait Affect a structure or process
that is found in one sex but not the other.
Sex-influenced traits Show up in both sex, but
expression of this trait differ between two sex
because of hormone difference - pattern baldness