Unite four Nucleotides and Nucleic acids

05 级生物技术一班　游琼英　

２００５２５０３４２０

Nucleic acid nucleotide

phosphate

Nucleoside

base

Pentose (戊糖)

｛ ｛

Base contain three kinds of Pyrimidine( 嘧啶 ) and two kinds of Purine( 嘌呤 )

five main kinds of base

胞嘧啶脲嘧啶

胸腺嘧啶

腺嘌呤 鸟嘌呤

Complementary strands of DNA,two polynucleotide chains associate by base pairing to form double-stranded DNA, A pairs with T, and G pairs with Cby forming specific hydrogen bonds,

ＰＥＮＴＯＳＥ

OHOH2C

H

OH

HOHOH

H H

Ribose( 核糖 )

OHOH2C

H

OH

HOHOH

H H

ＨDeoxy-ribose( 脱氧核糖 )

Can you find the differences between they ?

D-ribose (in RNA) 2-deoxy-D-ribose (in DNA) The difference - 2'-OH vs 2'-H This difference affects secondary structure and stability

About ribose and deoxy-ribose

nucleoside

OHOH2C

HH H

H

OH OH

N

N N

N

NH2

9

1'

they link to each other at 9 and 1’

OHOH2C

HH H

H

OH H

N

1'

N

O

NH2

1

They connect with each other both at 1 and 1’

Nucleic acids

Polymers linked 3' to 5' by phosphodiester bridges

Ribonucleic acid and deoxyribonucleic acid Know the shorthand notations Sequence is always read 5' to 3' In terms of genetic information, this corresp

onds to "N to C" in proteins

The backbone structure

Phosphodiester bridge( 磷酸二酯键 )

Phosphodiester bridge( 磷酸二酯键 ),

1\convant bones

2\link a nucleic acid reside to another

3\3’-OH to 5’-OH

The simple one

From 5’ end to 3’end

5’end3’ end

The basic feature of B-DNA

Remember that there have 5 features and 6 parameters 1. Double-Helix is Antiparallel Two Chains Right Helix The diameter of the helix in B-form DNA is 2 nm 2. Deoxyribose-phosphate （脱氧核糖 - 磷酸） backbone lies on the outside and bases on the inside Parameter 2 : A Rotation (转角 ) of 36 Degrees Per Base Parameter 3: Adjacent Bases are Separated by 0.34nm Parameter 4 : 10 Base Pairs Per Turn Parameter 5 : 3.4 nm Per Repeat Base Obliquity （碱基倾角） 0 Degree 3. Two Kinds of Grooves in the Surface 大沟 (major groove) ，小沟 (minor groove) 4. Bases are Restricted Pairing on the Inside 5. A Pair of Chains are Complementary Sequences

B form DNA is the most usual one in the six forms of DNA

What forces make they together?

1. Horizontal power—hydrogen bond （氢键）

2. Perpendicular power

— the stacking of bases （碱基堆积力） 3. Neutralising negatively charged phosph

ates of two chains

— ion bond （离子键）

Restriction endonuclease( 限制性内切酶 )

Come from bacteria can recognize the specific sequence Cut the DNA into pieces Contain palindromic 　 structure( 回文结

构 )

Chain termination method ( 末端测序法 )

Base on DNA polymerase reaction Run for four separate reactions Contain dATP, dCTP, dGTP, dTTP Also contain ddATP,ddCTP,ddGTP,ddTT

P,one of which is P-32-labelled.