Post on 29-Dec-2015
transcript
CO 04
The chromosome theory of inheritance
Fig. 4.5
Metaphase chromosome can be classified by centromere position
Fig. 4.6
Karyotype of a human male
Metaphase chromosomes
Table 4.1
Human: Y makes the difference.
Drosophila: ratio of number of X chromosome to copy number of autosome
Mentally retarded
Y is necessary for male fertility
Fig. 4.7
Mitosis Ensures that Every Cell in an Organism Carries the Same chromosomes
Fig. 4.8
Fig. 4.9
Fig. 4.10
Syncytium: a cell with two or more nuclei
Red: chromosomeGreen: spindle fibers
Fig. 4.11
Checkpoints help regulate the cell cycle
Fig. 4.12
Meiosis
Reduction division
Equational
division
Fig. 4.13a
Prophase I in meiosisChromosome condensation
Pairing of homologous chromosomes
Reciprocal exchange of the genetic information
tetrad
Fig. 4.13d
Fig. 4.13b
Meiosis I: metaphase
Chiasma ensures proper segregation of homologous chromosomes
Fig. 4.13e
Meiosis I
interphase
Fig. 4.13c
Meiosis II
Fig. 4.13f
Meiosis II
Segregation during meiosis
Segregation error: trisomies
trisomy 21: Down syndrome
extra X : Klinefeller male
Nondisjunction
Fig. 4.16
Male donkey: 31 autosomes
Female horse:32 autosomes
Hybrid animal: mule
Fig. 4.17
Meiosis contributes to
genetic diversity
213=107
Gametogenesis(gamete formation)
Germ cells(embryonic germ cells)
mitosisPrimary cells
(diploid)
meiosisgametes
differentiation
Primaryoocytes
Oogenesis: asymmetric meiotic division
500,000
diploteneDiploid germ cells (oogonia)
at metaphase II
Male germ cells
Meiosis I
Meiosis II
20 days 20 days 20 days
mitosis
Spermatogenesis: symmetric meiotic division
Validation of chromosome theory of inheritance
1. The chromosome theory correlates Mendel’s law with chromosome behavior during meiosis.
2. The transmission of particular chromosomes coincides with the transmission of specific traits
Fig. 4.20
X-linkage explains the inheritanceof alleles of the white gene
Criss-cross inheritance:The male inherit their eye color from their mothers, and vice vesa.
Fig. 4.21
Nondisjunction
1/2000
1/2000, W+ male; w femaleCytologically
with two X chromosomes
Fig. 4.22
Sex chromosome-linked disease
Red-green color blindness (recessive)
8% man, 0.44% women
Maternal grandfatehr 50% grandson
Fig. 4.23
Five properties of X-linked recessive disease:
1. More male than female.2. Never pass form father to son (son only get Y from father).3. Maternal father pass the disease to grandson.4. The disease often skip one generation from grandfather through a carrier
daughter.5. With the rare affected female, all her son will be affected and all her daughter will be carriers.
性聯遺傳低磷酸佝僂症
1. More female than male have the disease
2. Father to daughter
3. 50% of son and daughter
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