【南京大学 细胞遗传学】第三章 遗传物质的分子基础
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Prokaryotes: Monoploid Smallest RNA
3 genes
Bacteriaphage MS2
4 genes, 3569 nucleotides
DNA viruses
9-11 genes ØX174, 11 genes,
5386 nucleotides
Nucleoids
Chromosome Structure in Eukaryotes
Three levels of DNA package in eukaryotic chromosomes
Three levels of DNA package in eukaryotic chromosomes
Three levels of DNA package in eukaryotic chromosomes
104 to 2105 μm During metaphase of meiosis and mitosis
1 to 10 μm
Unineme
lampbrush PFGE analysis Autoradiography viscoelastometry
One large DNA molecule per chromosome:
Fruit fly
One large DNA molecule per chromosome: autoradiography
Growing cell fed with 3Hthymindine
Incorporated into DNA
Kavenoff et al (1960s)
Spread out the molecules with no tangles or overlaps on the slide
第三章 遗传物质的分子结构
DNA 和染色体的分子结构
Functions of the Genetic material Proof : DNA Structure of DNA and RNA chromosome of DNA and RNA Chromosome Structure
一、遗传物质的功能
1st level: Nucleosomes
H2a, H2b, H3, H4 Into 10 nm-diameter chromatin fiber
2nd level: 10 nm chromatin fiber
H1 Into 30 nm chromatin fiber
3rd level: 30 nm chromatin fiber
Chromosome Structure in Eukaryotes
Histones: H1, H2a, H2b, H3, H4 Exception: protamines in sperms
Multineme or unineme?
Typical eukaryotic chromosome: 1~20cm
One large DNA molecule per chromosome: PFGE
PFGE: pulsed-field gel electrophoresis
Intermittent and alternating electric fields Superior separation of very large DNA molecular DNA size resolution depended on
证明遗传物质时DNA的第一个直接证据
发现： 只有脱氧核糖核酸酶（DNase) 处理的DNA影响IIR→IIIS转化 活性，且转化活性完全消失。
结论： 脱氧核糖核酸（DNA)是遗传物 质。
噬菌体T2中DNA携带遗传信息的证据
几点说明： 1. 噬菌体T2的繁殖 在大肠杆菌胞内进 行。 2.DNA含磷 3.蛋白含硫
A = T, G = C
Structure of DNA
Base pairing in DNA
2 nm
Rosalind Elsie Franklin
DNA : Double helix
X-ray crystallography Diffracted Double helix Full turn: 3.4 nm 10 layers per turn 2-nm diameter Hydrophobic nitorgenous bases in interior
Switch time and angle of electronodes
The number of different sized DNA molecules was equal to number of nonhomologous chromosomes
Can not separate very large chromosomes
Nuclease & protease treatments
DNase
Destroy in both the axis and the loops
RNase & protease
Keep the continuity of axis/loop 2 nm in diameter Same as the diameter of a DNA double helix
Aqueous soln
Z-DNA
Crystal uncovered by X-ray diffraction Alternating G:C and C:G paring
DNA structure: Negative Supercoils in vivo
Chromosome Structure in Prokaryotes and Virus
胸腺嘧啶 腺嘌呤
鸟嘌呤
嘌呤核苷酸
DNA : polymer
Additional Evidence
Mitosis
DNA double
Meiosis
Gamates with ½ DNA contents of diploid cells
Erwin Chargaff
DNA composition of different species Chargaff rule
Genotypic function:
Replication Transmit from parents to offspring
Phenotypic function
Gene expression Growth of organism from the single zygote to the mature adult
Up to 1.2 cm 31010 daltons
Viscoelastometry
Viscosity of molecules in soln
Largest chromosome in fly 4.11010 daltons
Three levels of DNA package in eukaryotic chromosomes
Telomeres
Conserved
T1-4A0-1G1-8 TTAGGG, vertebrate TTGGG, tetrahymena TTTAGGG, Arabidopsis
Number
500 to 3000
G rich
TRF-2 (telomere repeatbinding factor-2)
Structure of DNA—double helix
Structure of DNA—double helix
Structure of DNA—double helix
A-DNA
High salt, partially dehydrate DNA-RNA heteroduplexes
B-DNA
肺炎双球菌的重组
现象： 小鼠体内热杀死的ⅢS肺炎双球 菌（有致病性）在有活的IIR（无 致病性）存在时恢复活性。
注意点： 1.小鼠体内恢复活性的ⅢS型肺 炎双球菌有ⅢS型的多糖荚膜。 2.没有荚膜的R型细菌能突变成 有荚膜的S型。
结论： 死亡的ⅢS型细菌的一些成分将 IIR型转化成ⅢS型。
问题： 实验并没有直接证明DNA参与了 转化过程
发现： 1. 噬菌体T2用32P 标记，被感染的细 菌内部发现放射性 2.噬菌体T2用35S 标记，被感染的细 菌大多数放射性消 失
缺陷： 发现有35S随DNA 一起进入宿主，说 明噬菌体蛋白的小 片段包含遗传信息
解决方法： 转染(transfection)
证明烟草花叶病毒(TMV)的遗传物质是RNA
lampbrush
Prophase I of oogenesis in amphibians
800 μm long Central axial region Numerous pairs of lateral loops
Transcrtionally active regions of single chromatids
Evolutionary function
mutation Vari
1.Transformation in Bacteria
Griffith in 1928-细菌的转化 肺炎双球菌的重组
2. DNA mediates transformation
Avery, MacLeod, McCarty in 1944 pneumococcus
3. Genetic information in bacteriophage T2
Harshey, Chase in 1952
4. RNA stores the genetic information in some virus
Fraenkel-Conrat in 1957 Tobacco masaic virus (TMV)
Nonhistone proteins Scaffold Into tightly packed metaphase chromosomes
Centromeres
CEN region
replaceable
Function
Degrading Prevent Fusion Facilitate replication w/o loss of materials
TMV的重构实验
发现： 重组病毒的子代在 基因型和表型上都 与提供RNA的亲代 病毒相同。 结论： TMV的遗传信息存 储于RNA而不是蛋 白质中。
Structure of DNA and RNA
核酸由称为核苷酸的重复单位组成
1分子 磷酸盐
1分子 五碳糖
嘧啶核苷酸
1分子环 状含氮 碱基
尿嘧啶
胞嘧啶
3 genes
Bacteriaphage MS2
4 genes, 3569 nucleotides
DNA viruses
9-11 genes ØX174, 11 genes,
5386 nucleotides
Nucleoids
Chromosome Structure in Eukaryotes
Three levels of DNA package in eukaryotic chromosomes
Three levels of DNA package in eukaryotic chromosomes
Three levels of DNA package in eukaryotic chromosomes
104 to 2105 μm During metaphase of meiosis and mitosis
1 to 10 μm
Unineme
lampbrush PFGE analysis Autoradiography viscoelastometry
One large DNA molecule per chromosome:
Fruit fly
One large DNA molecule per chromosome: autoradiography
Growing cell fed with 3Hthymindine
Incorporated into DNA
Kavenoff et al (1960s)
Spread out the molecules with no tangles or overlaps on the slide
第三章 遗传物质的分子结构
DNA 和染色体的分子结构
Functions of the Genetic material Proof : DNA Structure of DNA and RNA chromosome of DNA and RNA Chromosome Structure
一、遗传物质的功能
1st level: Nucleosomes
H2a, H2b, H3, H4 Into 10 nm-diameter chromatin fiber
2nd level: 10 nm chromatin fiber
H1 Into 30 nm chromatin fiber
3rd level: 30 nm chromatin fiber
Chromosome Structure in Eukaryotes
Histones: H1, H2a, H2b, H3, H4 Exception: protamines in sperms
Multineme or unineme?
Typical eukaryotic chromosome: 1~20cm
One large DNA molecule per chromosome: PFGE
PFGE: pulsed-field gel electrophoresis
Intermittent and alternating electric fields Superior separation of very large DNA molecular DNA size resolution depended on
证明遗传物质时DNA的第一个直接证据
发现： 只有脱氧核糖核酸酶（DNase) 处理的DNA影响IIR→IIIS转化 活性，且转化活性完全消失。
结论： 脱氧核糖核酸（DNA)是遗传物 质。
噬菌体T2中DNA携带遗传信息的证据
几点说明： 1. 噬菌体T2的繁殖 在大肠杆菌胞内进 行。 2.DNA含磷 3.蛋白含硫
A = T, G = C
Structure of DNA
Base pairing in DNA
2 nm
Rosalind Elsie Franklin
DNA : Double helix
X-ray crystallography Diffracted Double helix Full turn: 3.4 nm 10 layers per turn 2-nm diameter Hydrophobic nitorgenous bases in interior
Switch time and angle of electronodes
The number of different sized DNA molecules was equal to number of nonhomologous chromosomes
Can not separate very large chromosomes
Nuclease & protease treatments
DNase
Destroy in both the axis and the loops
RNase & protease
Keep the continuity of axis/loop 2 nm in diameter Same as the diameter of a DNA double helix
Aqueous soln
Z-DNA
Crystal uncovered by X-ray diffraction Alternating G:C and C:G paring
DNA structure: Negative Supercoils in vivo
Chromosome Structure in Prokaryotes and Virus
胸腺嘧啶 腺嘌呤
鸟嘌呤
嘌呤核苷酸
DNA : polymer
Additional Evidence
Mitosis
DNA double
Meiosis
Gamates with ½ DNA contents of diploid cells
Erwin Chargaff
DNA composition of different species Chargaff rule
Genotypic function:
Replication Transmit from parents to offspring
Phenotypic function
Gene expression Growth of organism from the single zygote to the mature adult
Up to 1.2 cm 31010 daltons
Viscoelastometry
Viscosity of molecules in soln
Largest chromosome in fly 4.11010 daltons
Three levels of DNA package in eukaryotic chromosomes
Telomeres
Conserved
T1-4A0-1G1-8 TTAGGG, vertebrate TTGGG, tetrahymena TTTAGGG, Arabidopsis
Number
500 to 3000
G rich
TRF-2 (telomere repeatbinding factor-2)
Structure of DNA—double helix
Structure of DNA—double helix
Structure of DNA—double helix
A-DNA
High salt, partially dehydrate DNA-RNA heteroduplexes
B-DNA
肺炎双球菌的重组
现象： 小鼠体内热杀死的ⅢS肺炎双球 菌（有致病性）在有活的IIR（无 致病性）存在时恢复活性。
注意点： 1.小鼠体内恢复活性的ⅢS型肺 炎双球菌有ⅢS型的多糖荚膜。 2.没有荚膜的R型细菌能突变成 有荚膜的S型。
结论： 死亡的ⅢS型细菌的一些成分将 IIR型转化成ⅢS型。
问题： 实验并没有直接证明DNA参与了 转化过程
发现： 1. 噬菌体T2用32P 标记，被感染的细 菌内部发现放射性 2.噬菌体T2用35S 标记，被感染的细 菌大多数放射性消 失
缺陷： 发现有35S随DNA 一起进入宿主，说 明噬菌体蛋白的小 片段包含遗传信息
解决方法： 转染(transfection)
证明烟草花叶病毒(TMV)的遗传物质是RNA
lampbrush
Prophase I of oogenesis in amphibians
800 μm long Central axial region Numerous pairs of lateral loops
Transcrtionally active regions of single chromatids
Evolutionary function
mutation Vari
1.Transformation in Bacteria
Griffith in 1928-细菌的转化 肺炎双球菌的重组
2. DNA mediates transformation
Avery, MacLeod, McCarty in 1944 pneumococcus
3. Genetic information in bacteriophage T2
Harshey, Chase in 1952
4. RNA stores the genetic information in some virus
Fraenkel-Conrat in 1957 Tobacco masaic virus (TMV)
Nonhistone proteins Scaffold Into tightly packed metaphase chromosomes
Centromeres
CEN region
replaceable
Function
Degrading Prevent Fusion Facilitate replication w/o loss of materials
TMV的重构实验
发现： 重组病毒的子代在 基因型和表型上都 与提供RNA的亲代 病毒相同。 结论： TMV的遗传信息存 储于RNA而不是蛋 白质中。
Structure of DNA and RNA
核酸由称为核苷酸的重复单位组成
1分子 磷酸盐
1分子 五碳糖
嘧啶核苷酸
1分子环 状含氮 碱基
尿嘧啶
胞嘧啶