哈佛大学：《分子生物学》课程PPT教学课件（英文版）In vivo dna binding pattern of the polycomb

Facts(“ vocabulary Concepts Techniques Quantitation

Facts (“vocabulary”) Concepts Quantitation Techniques

In vivo dna binding pattern of the polycomb Txn factor What are the genes to which it binds? 2. How does it affect these genes? 3. hat determines where it Binds?? FIG3 Polycomb-binding sites. The picture shows the association of the Polycomb protein with specific sites of the Drosopbila genome, revealed by immunostaining salivary gland pOlytene chromosomes with antibodies against the Polycomb protein(Preparation by

In vivo DNA binding pattern of the Polycomb Txn Factor 1. What are the genes to which it binds? 2. How does it affect these genes? 3. What determines where it Binds??

O-P=0 H2CO Base Nitrogenous base HH Sugar o H hosphate Hc Bas H H HC ase HH o H

1 Nitrogenous base Sugar Phosphate

Evidence for the double helix 1. Fiber Diffraction data helical helical geometry 10 laver 34A° spacing(1A°=1010m) L ines 34A° pitch Between Patterns 2. Structure of dcTP 10 Residues 3. Base tautomerism Per turn) 3. Chargaff rules A=TG=C IGURE 4.9 Evidence for the structure of DNA. this photograph, taken by Rosalind Franklin, shows the x-ray diffraction pattern produced by wet DNA fibers. It played a key role in the lucida tion of DNA structure. The cross pattern indi- cates a helical structure, and the strong spots at top and bottom correspond to a helical rise of 0. 34 nm. The layer line spacing is one-tenth of the distance from the center to either of IA these spots, showing that there are 10 base pairs per repeat

1A 2. Structure of dCTP 3. Base Tautomerism 3. Chargaff rules - A=T, G=C helical 10 layer Lines Between Cross Patterns (10 Residues Per turn) Evidence for the Double Helix 1. Fiber Diffraction data: -Helical geometry -3.4 A º spacing (1Aº = 10-10 m) -34 A º pitch

NIH (not in handout)

NIH (not in handout)

HOCH2∠O、OH HO H β-2- deoxyribose

-2’-deoxyribose 2

Sugar Pucker" Conformations A dNA Base Base 3′-endo 3-endo,2′exo B DNA Base Base 2′-endo 2′-endo.3′exo

Sugar “Pucker” Conformations A DNA B DNA 3

Pyrimidines NH H—N。45C-CH 3 5C—H 0=C216C-H Thymine Cytosine (C) NH2 Purines H-N. 6 5C H-C3,4。8CH H2N-CS3CN Adenine Guanine (A) (G)

Pyrimidines Purines 4

Base tautomerization G(Keto G(Enol) A N A2N 2N 9999 0.01

G (Keto) G (Enol) A 99.99% 0.01% Base Tautomerization 5

NH NH N N N N C CH CH HC C HC C HOCH2O O-P-0-P-0—POCH2O O H H o H HO H Deoxyadenosine Deoxyadenosine 5-triphosphate (A nucleoside) (dATP) A nucleotide Base Nucleoside Nucleotide Adenine Deoxy )adenosine (d)A(mono, di-, tri) phosphate Guanine Deoxy )guanosi (dG(mono, di-, tri) phosphate Thymine Deoxy )thymidine (dT(mono, di-, tri) phosph Cytosine Deoxy )cytidin Ine (d)C(mono, di- tri) phosphate

Base Adenine Guanine Thymine Cytosine Nucleoside (Deoxy)adenosine (Deoxy)guanosine (Deoxy)thymidine (Deoxy)cytidine Nucleotide (d)A (mono, di-, tri) phosphate (d)G (mono, di-, tri) phosphate (d)T (mono, di-, tri) phosphate (d)C (mono, di-, tri) phosphate 6 1’ 9