中山大学生物化学课件(1)

DNA Structure: Why A/B/Z configuration? (1)
DNA Structure: Why A/B/Z configuration? (2)
DNA Structure: Why A/B/Z configuration? (3)
DNA Structure: Palindromes & mirror repeats
DNA Structure
RNA Structure
DNA Structure
Double Helix
DNA Structure: double helix
In addition to hydrogen bonds, base-stacking interactions (hydrophobic interaction, van der Waals force, dipole-dipole interaction) are very important in stabilizing DNA structure.
Some nucleotides are regulatory molecules
The End
Configuration of Ribose in Nucleotides
Bases in nucleotides
Modifications of Nucleotides (1)
Modifications of Nucleotides (2)
§8 Nucleotides & nucleic acids
§8.1 Nucleotides §8.2 Nucleic Acids §8.3 Nucleic Acid Chemistry §8.4 Other Functions of Nucleotides
Nucleotides carry chemical energy in cells
Adenine nucleotides are components of many enzyme cofactors
§8.2 Nucleic Acids
Brief History about DNA
DNA Structure
RNA Structure
mRNAs code for Polypeptide Chains
§8 Nucleotides & nucleic acids
§8.1 Nucleotides §8.2 Nucleic Acids §8.3 Nucleic Acid Chemistry §8.4 Other Functions of Nucleotides
DNA Structure: three helix forms (1)
All contain 21 base pairs
Minor groove
Major groove
A-DNA
B-DNA
Z-DNA
DNA Structure: three helix forms (2)
All contain 21 base pairs
......
1928, Griffith’s transformation experiment (1)
1928, Griffith’s transformation experiment (2)
1928, Griffith’s transformation experiment (3)
1928, Griffith’s transformation experiment (4)
1944, Avery-MacLeod-McCarty experiment
Franklin’s X-ray picture for DNA
1952, Alfred D. Hershey & Martha Chase experiment
§8.2 Nucleic Acids
Brief History about DNA
源自文库
DNA Structure: four DNA strands (2)
Unusual DNA structures (including triple helix and tetraplex) tend to appear at sites where important events in DNA metabolism (replication, recombination, transcription) are initiated or regulated
§8 Nucleotides & nucleic acids
§8.1 Nucleotides §8.2 Nucleic Acids §8.3 Nucleic Acid Chemistry §8.4 Other Functions of Nucleotides
b-D-Ribonucleotide
b-D-deoxyribonucleotide
Nonenzymatic transformations (2)
Formation of pyrimidine dimers induced by UV light
Recovery
Some bases of DNA are methylated
DNA Sequencing
DNA polymerase
DNA Structure: circular DNA
Linking num. ＝ Twist + Writhe
DNA Structure: condensation in eukaryotes
H2A,H2B,H3,H4
DNA Structure: condensation in eukaryotes
DNA Structure: Hairpin
DNA Structure: Cruciform
DNA Structure: three DNA strands
Waston-Crick Pairs
Hoogsteen Pairs
DNA Structure:
H DNA
DNA Structure: four DNA strands (1)
Sanger method is also called dideoxy method
荧光标记的策略之一
DNA polymerase DNA polymerase DNA polymerase dATP, dGTP, dTTP, dCTP dATP, dGTP, dTTP, dCTP dATP, dGTP, dTTP, dCTP ddATP ddGTP ddTTP ddATP ddATP ddATP ddGTP ddGTP ddGTP ddTTP ddTTP ddTTP
UV absorption
Double-helical DNA & RNA can be denatured (1)
Double-helical DNA & RNA can be denatured (2)
Melting point
Nucleic acid hybrid
Nonenzymatic transformations (1)
§8.1 Nucleotides §8.2 Nucleic Acids §8.3 Nucleic Acid Chemistry §8.4 Other Functions of Nucleotides
§8.2 Nucleic Acids
Brief History about DNA
DNA Structure
DNA polymerase dATP, dGTP, dTTP, dCTP ddCTP
ddCTP ddCTP ddCTP
荧 光 标 记 的 策 略 之 二
Chemical synthesis of DNA Has been automated
§8 Nucleotides & nucleic acids
RNA Structure
Brief History about DNA
1869, Miescher isolates nuclein 1928, Griffith finds Streptococcus transformation 1944, Avery discovered that DNA was the genetic material By 1947, Chargaff had developed a series of rules based on a survey of DNA composition in organisms Early in 1950s, Wilkins & Franklin used X-ray crystallography to study the structure of DNA 1952, Hershey farther showed that DNA was the genetic material 1953, Watson & Crick propose the double-helical structure of DNA
A-DNA
B-DNA
Z-DNA
DNA Structure: three helix forms (3)
All contain 21 base pairs
Z-DNA A-DNA
B-DNA
DNA Structure: three helix forms (5)
→B-DNA is the most stable structure in physiological condition. →Whether A-DNA occurs in cell is uncertain. Most short DNAs tend to crystallize in A form. →There is evidence for some short stretches (tracts) Z-DNA in both prokaryotes and eukaryotes. These Z-DNA tracts may play an as yet undefined role in the regulation of the expression of some genes or in genetic recombination