分子生物学第2章
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Human ancestors were ape-like animals millions of years ago. But modern humans are very different from apes.
So, the genetiBiblioteka Baidu material must have also changed
Nucleic acids (mainly DNA) In this chapter we examine nucleic acids and how they are suited for their function.
Proteins
2 / 50
Chapter 2 Nucleic acids
2.1 Properties of a Genetic
The direction of nucleic acid is from
5’-end to 3’-end.
Sugar-phosphate backbone / 糖-磷酸骨架
Negative charges
Between the two ends of the DNA is
a simple, repeating structure of sugars connected by phosphodiester bonds. This structure is called the sugar-phosphate backbone.
9 CH2OH CH2OH
1
苷羟基
3) Triphosphate
/ 三磷酸
NH2 6 5 7 N 1N 2 O O O 5’
2
The triphosphate group is connected
to the 5’ carbon of the sugar.
8
N 4 3
N9
O-―P―O―P―O―P―O―CH OOOHC 4’
MUTAtiOn
9 / 50
4. It must be able to be copied
It must replicate accurately so that progeny cells
have the same genetic information as the parental cells.
6 / 50
It must be stable / 它必须是稳定的
In other aspects, the genetic material must also be
stable for long periods of time within one generation.
Age: 15
Age: 45
ribose.
?
DNA中有T无U是进化的结果
C U
• DNA中如有U
错配修复系统不能分辨两 类U，对突变难以修复
存在潜在的遗传突变风险 DNA修复系统对 C突变进行修复 保持生物遗传物质 的稳定性
DNA中有T无U 无后顾之忧DNA扩增
The ribose 2’-OH group of RNA is absent
A genetic material must have four properties.
One question is: Is there any such material?
For life on earth, a class of molecules does have all the four necessary properties. These molecules are called nucleic acids.
Ribonucleotides and deoxyribonucleotides
核糖核苷酸 与 脱氧核糖核苷酸
Phosphodiester bond / 磷酸二酯键
Triphosphate group of one nucleotide reacts with the 3’-OH (hydroxyl group ) of another nucleotide. In this reaction, two phosphates are removed from one nucleotide, and the two nucleotides are connected by phosphodiester bonds.
19 / 50
Nucleic acid polymer is
linear, meaning it has no branches.
5’-triphosphate group
Five prime end
and three prime end 三一撇末端 与 五一撇末端
3’- hydroxyl group
O CH 1’ CH 2’ OH CH 3’ OH
It is often used as the energy
source for certain reactions.
Adenosine-5’-triphosphate 腺嘌呤核苷-5’-三磷酸
Nucleotide Acid
核苷中戊糖的羟基与磷酸基发生酯化形成的化 合物即为核苷酸. ATP AMP ADP
Age: 75
No change !
No change !
7 / 50
3. It must have some capacity for change
It must be capable of change. Without change,
organisms would be incapable of variation and adaptation, and evolution could not occur.
It must contain the information
for an organism’s cell structure, function, development, and reproduction.
2. It must be stable
in a stable form
The necessary traits of organism are passed down
Chapter 2
Nucleic acids 核 酸
1 / 50
Nucleic acids: the information carrier
Proteins are so complicated, there must be something to hold information for making them. Actually, nucleic acids hold the information for how to make proteins.
11 / 50
2.2.1 Nucleotides (核苷酸 )
Nucleic Acid(NA) Polynucleotide chain(poly Nt) Nucleotide Acid(Nt) － basic unit Nucleoside (Ns)
nitrogenous
Monophosphate(Mp)
4.It must be able to be copied.
4 / 50
1.
It must be able to hold information for how to make proteins
We have learned that proteins are very
important to organisms and the information for making them must be held in the genetic material.
2.6 Experiments
2.5 RNA（核糖核酸）
2.6 实验研究
3 / 50
2.1 Properties of a Genetic Material
If one thing is to be used as the genetic material for life, what properties it must have? 1.It must be able to hold information for how to make proteins. 2. It must be stable. 3.It must have some capacity for change.
Each child has all the same components as the parents.
This means that each child must receive his own complete set of the genetic material.
10 / 50
2.2 Nucleic Acids and DNA structure
Material 2.2 Nucleic Acids and DNA 2.2 核酸与DNA结构
2.1 遗传物质的性质
structure
2.3 DNA as the Genetic Material 2.3 DNA作为遗传物质 2.4 DNA in the Cell 2.4 细胞中的DNA
2.5 RNA (Ribonucleic Acid)
14 / 50
2) Sugar / 糖
呋喃型环状结构： β-D-戊糖、 β-D-2-脱氧戊糖（脱氧核糖）
hydroxyl group No oxygen here !
15 / 50
Nucleoside(核苷)
碱基和戊糖以N-糖苷键相连缩和成核苷。戊糖的 C1与嘌呤的N9或与嘧啶的N1相连接，构成N-C 键（N-糖苷键---N-glycosidic bond ）
Ringed structure
Each ring has two nitrogen atoms.
Different chemical groups such as amino and carbonyl groups may be attached to the rings to give each base unique chemical properties.
1) a nitrogenous base
3) a triphosphate The nitrogenous base is connected to the 1’ carbon of sugar by an N-glycosidic bond.
2) a sugar
13 / 50
1) Nitrogenous base
in DNA This difference leads to a greater resistance of DNA to alkaline hydrolysis (pH11.5).
8 / 50
We can say that, if the genetic material had been completely stable, human beings would never have appeared.
基因突变是从猿到人的关键
劳动 和自然变异促
进了基因突变
染色体数目的变异 某些基因突变 不适个体被淘汰
21 / 50
What is Significance of Chemical
Differences between DNA and RNA
DNA contains thymine instead of uracil. DNA contains 2-deoxyribose instead of
from generation to generation with very little change, often for millions of years.
Lizard: 1,000,000 B.C.
Lizard: 2009 A.D.
genetic material No change !
Base
Deoxy-ribose ( Ribose )
Purin (pu) Pyrimidine(py) (Adenine) (Thymine)/ (Uracil) (Guanine) (Cytosine)
Nucleotides are composed of three parts:
N-glycosidic bond
So, the genetiBiblioteka Baidu material must have also changed
Nucleic acids (mainly DNA) In this chapter we examine nucleic acids and how they are suited for their function.
Proteins
2 / 50
Chapter 2 Nucleic acids
2.1 Properties of a Genetic
The direction of nucleic acid is from
5’-end to 3’-end.
Sugar-phosphate backbone / 糖-磷酸骨架
Negative charges
Between the two ends of the DNA is
a simple, repeating structure of sugars connected by phosphodiester bonds. This structure is called the sugar-phosphate backbone.
9 CH2OH CH2OH
1
苷羟基
3) Triphosphate
/ 三磷酸
NH2 6 5 7 N 1N 2 O O O 5’
2
The triphosphate group is connected
to the 5’ carbon of the sugar.
8
N 4 3
N9
O-―P―O―P―O―P―O―CH OOOHC 4’
MUTAtiOn
9 / 50
4. It must be able to be copied
It must replicate accurately so that progeny cells
have the same genetic information as the parental cells.
6 / 50
It must be stable / 它必须是稳定的
In other aspects, the genetic material must also be
stable for long periods of time within one generation.
Age: 15
Age: 45
ribose.
?
DNA中有T无U是进化的结果
C U
• DNA中如有U
错配修复系统不能分辨两 类U，对突变难以修复
存在潜在的遗传突变风险 DNA修复系统对 C突变进行修复 保持生物遗传物质 的稳定性
DNA中有T无U 无后顾之忧DNA扩增
The ribose 2’-OH group of RNA is absent
A genetic material must have four properties.
One question is: Is there any such material?
For life on earth, a class of molecules does have all the four necessary properties. These molecules are called nucleic acids.
Ribonucleotides and deoxyribonucleotides
核糖核苷酸 与 脱氧核糖核苷酸
Phosphodiester bond / 磷酸二酯键
Triphosphate group of one nucleotide reacts with the 3’-OH (hydroxyl group ) of another nucleotide. In this reaction, two phosphates are removed from one nucleotide, and the two nucleotides are connected by phosphodiester bonds.
19 / 50
Nucleic acid polymer is
linear, meaning it has no branches.
5’-triphosphate group
Five prime end
and three prime end 三一撇末端 与 五一撇末端
3’- hydroxyl group
O CH 1’ CH 2’ OH CH 3’ OH
It is often used as the energy
source for certain reactions.
Adenosine-5’-triphosphate 腺嘌呤核苷-5’-三磷酸
Nucleotide Acid
核苷中戊糖的羟基与磷酸基发生酯化形成的化 合物即为核苷酸. ATP AMP ADP
Age: 75
No change !
No change !
7 / 50
3. It must have some capacity for change
It must be capable of change. Without change,
organisms would be incapable of variation and adaptation, and evolution could not occur.
It must contain the information
for an organism’s cell structure, function, development, and reproduction.
2. It must be stable
in a stable form
The necessary traits of organism are passed down
Chapter 2
Nucleic acids 核 酸
1 / 50
Nucleic acids: the information carrier
Proteins are so complicated, there must be something to hold information for making them. Actually, nucleic acids hold the information for how to make proteins.
11 / 50
2.2.1 Nucleotides (核苷酸 )
Nucleic Acid(NA) Polynucleotide chain(poly Nt) Nucleotide Acid(Nt) － basic unit Nucleoside (Ns)
nitrogenous
Monophosphate(Mp)
4.It must be able to be copied.
4 / 50
1.
It must be able to hold information for how to make proteins
We have learned that proteins are very
important to organisms and the information for making them must be held in the genetic material.
2.6 Experiments
2.5 RNA（核糖核酸）
2.6 实验研究
3 / 50
2.1 Properties of a Genetic Material
If one thing is to be used as the genetic material for life, what properties it must have? 1.It must be able to hold information for how to make proteins. 2. It must be stable. 3.It must have some capacity for change.
Each child has all the same components as the parents.
This means that each child must receive his own complete set of the genetic material.
10 / 50
2.2 Nucleic Acids and DNA structure
Material 2.2 Nucleic Acids and DNA 2.2 核酸与DNA结构
2.1 遗传物质的性质
structure
2.3 DNA as the Genetic Material 2.3 DNA作为遗传物质 2.4 DNA in the Cell 2.4 细胞中的DNA
2.5 RNA (Ribonucleic Acid)
14 / 50
2) Sugar / 糖
呋喃型环状结构： β-D-戊糖、 β-D-2-脱氧戊糖（脱氧核糖）
hydroxyl group No oxygen here !
15 / 50
Nucleoside(核苷)
碱基和戊糖以N-糖苷键相连缩和成核苷。戊糖的 C1与嘌呤的N9或与嘧啶的N1相连接，构成N-C 键（N-糖苷键---N-glycosidic bond ）
Ringed structure
Each ring has two nitrogen atoms.
Different chemical groups such as amino and carbonyl groups may be attached to the rings to give each base unique chemical properties.
1) a nitrogenous base
3) a triphosphate The nitrogenous base is connected to the 1’ carbon of sugar by an N-glycosidic bond.
2) a sugar
13 / 50
1) Nitrogenous base
in DNA This difference leads to a greater resistance of DNA to alkaline hydrolysis (pH11.5).
8 / 50
We can say that, if the genetic material had been completely stable, human beings would never have appeared.
基因突变是从猿到人的关键
劳动 和自然变异促
进了基因突变
染色体数目的变异 某些基因突变 不适个体被淘汰
21 / 50
What is Significance of Chemical
Differences between DNA and RNA
DNA contains thymine instead of uracil. DNA contains 2-deoxyribose instead of
from generation to generation with very little change, often for millions of years.
Lizard: 1,000,000 B.C.
Lizard: 2009 A.D.
genetic material No change !
Base
Deoxy-ribose ( Ribose )
Purin (pu) Pyrimidine(py) (Adenine) (Thymine)/ (Uracil) (Guanine) (Cytosine)
Nucleotides are composed of three parts:
N-glycosidic bond