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一、染色质 chromatin
二、染色体 chromosome
三、人类染色体的正常核型 the normal human karyotype
四、染色体的多态性 chromosome polymorphism
第二节 遗传的细胞基础Cellular Basis of Inheritance
( 一 ) 染色质的分子结构 chromatin structure
( 二 ) 常染色质和异染色质 euchromatin and heterochromatin
( 三 ) 性染色质 (sex chromatin)
X chromatin
Y chromatin
Chromatin
一、染色质( 1 )
Chromatin
一、染色质( 2 )
1 Chemical components of chromatin: DNA 、 protein 、 a little of RNA
2 Higher levels of chromatin structure:
Four levels of DNA packing
Chromatin
一、染色质( 3 )
30 nm chromatin fiber of packed nucleosomes.
Section of chromosome in an extended form
Chromatid
“Beads-on-a-string” form of chromatin.
Higher levels of chromatin structure: Four levels of DNA packing
Cell
Histones
DNA
Chromatin
一、染色质( 4 )
核小体 /nucleosome
Chromatin
一、染色质( 5 )
DNA
nucleosome
Chromatid
×7
×6
×40
×5
×8400
Chromatin
一、染色质( 6 )
30 nm chromatin fiber of packed nucleosomes.
Section of chromosome in an extended form
染色质 chromatinInterphase。
染色体 chromosomeM phase
Chromatin
一、染色质( 7 )
常染色质 (heterochromatin) 和异染色质 (euchromatin )
euchromatin: active, less compact 。Heteromatin: repressed, concentrated 。
heterochromatin
euchromatin
Chromatin
一、染色质( 8 )
1949 , Barr
Barr body
X body
Chromatin
一、染色质( 9 )
X 染色质 (X chromatin) : female, interphase, 1μm body, heterochromatin
Chromatin
一、染色质( 10)
1961 年, Lyon X 染色体失活假说 (Lyon hypothesis) :①only one of the two X-chromosomes is genetically active in female cells. The inactive X chromosome is silenced by packaging into transcriptionally inactive heterochromatin ②The choice of which X chromosome will be inactivated is random in placental mammals such as mice and humans, but once an X chromosome is inactivated it will remain inactive throughout the lifetime of the cell.
Chromatin
一、染色质( 11)
Dosage compensation effect
剂量补偿效应
Y 染色质 (Y chromatin):
male
interphase
0.3 μm body,
Q-bright region of Y chromosome
Chromatin
一、染色质( 12)
structure;:• 短臂 p• 长臂 q• 着丝粒 centromere
主缢痕 primary constriction
• 端粒 telomere• 次缢痕 secondary
constriction• 随体 satellite
二、染色体 (1)Chromosome
Structure, type and number
Type
二、染色体 (2)Chromosome
Metacentric chromosome: 1/2 -5/8
Submetacentric chromosome: 5/8 – 7/8
Acrocentric chromosome: 7/8 - telomere
( 一 ) 非显带核型Karyotype without band
核型 karyotype
核型分析 karyotype analysis
三、人类染色体的正常核型( 1)The normal human karyotype
type methods
G banding trypsin, Giemsa
Q banding quinacrine mustard QM
R banding NaCl, Giemsa
T banding Heat, Giemsa
C banding NaOH, Giemsa
N banding AgNO3
三、人类染色体的正常核型( 2)The normal human karyotype
Q banding G banding Model of G- and R-banding
染色体显带Q-; G-; R-; C-;
三、人类染色体的正常核型( 3)The normal human karyotype
• 界标 landmark• 区 region• 带 band
1p35
高分辨显带High resolution banding
三、人类染色体的正常核型( 4)The normal human karyotype
karyotype with band
三、人类染色体的正常核型( 5)The normal human karyotype
三、人类染色体的正常核型( 6)The normal human karyotype
Number and structure
男性染色体46, XY
女性染色体46 , XX
四、染色体的多态性( 1 )chromosome polymorphism
FISH
X 染色体 Y 染色体 13 号染色体 18 号染色体 21 号染色体
四、染色体的多态性( 2 )chromosome polymorphism
四、染色体的多态性( 3 )
Detection of tumor
人类细胞遗传学国际命名体制 (ISCN, 1995)(An International System for Human Cytogenetic Nomenclature)
p— 短臂 q— 长臂del— 缺失 dup— 重复i— 等臂 inv— 倒位rob— 罗氏易位 t— 易位der— 衍生染色体 ter— 末端
46,XX,t(1;2)(p21;q23)
染色体总数,性染色体组成, 染色体变化染色体号;臂号;区号;带号; (.亚带)
染色体命名
四、染色体的多态性( 4 )chromosome polymorphism
47, XY, +2145, X46, XX, del(6)(p24)47, XXY45, XY, -14, -21, +rob(14;21)(q11;p11)
染色体表达式举例:
四、染色体的多态性( 5 )chromosome polymorphism