分子生物学课件genome1.pptVIP

2. 2Structure of Genome (基因组) ways Chromosome # Evolution Sequencing Denaturation (变性) renaturation (复性) Denature: It suddenly happened!! Narrow range of Temperature Short period of Time “Tm” determined by GC or AT content How to detect denatured DNA? Absorption peak: nucleic acid: 260 protein: 280 Ratio 260:280 DNA: 1.8 RNA: 2.0 Concentration purity How to detect denatured DNA? hyperchromic effect (增色效应 ) Absorption increased after de-naturing Renaturation is infected by— Ion Temperature DNA concentration Incubation time DNA complexity Kinetics of renaturation Re-naturing of Eukaryotic genome Types of DNA sequences: according to “concentration” in Genome Highly repeated DNA:Satellite DNA Unit: 5 to hundreds bp Size: millions bp Localization: centromere Function: unknown Euchromatin (常染色质) comprises all of the genome in the interphase nucleus except for the heterochromatin. Heterochromatin (异染色质 ) describes regions of the genome that are permanently in a highly condensed condition, are not transcribed, and are late-replicating. May be constitutive (组成型异染色质 ) or facultative (兼性异染色质 ). Example 1 Fruit fly Satellite DNAs of D. virilis are related. More than 95% of each satellite consists of a tandem repetition of the predominant sequence. Example 2 Mouse The alignment of quarter-repeats identifies homologies between the first and second half of each half-repeat. Highly repeated DNA:mini-Satellite DNA Unit: 12 to 100 bp Units: 3000 units Property: polymorphism (多态性) Highly repeated DNA:mini-Satellite DNA Unit: 12 to 100 bp Units: 3000 units Property: polymorphism Function: disturb neighbor Highly repeated DNA:micro-Satellite DNA Unit: 1 to 5 bp Units: 50 to 100 bp #: 30000 ( Homo sapiens) Localization: all over the genome Property: polymorphism (more than mini-sat.) Moderately repeated DNA sequences Coding Non-coding Coding tRNA rRNA histone Non-coding SINE: short interspersed element; 500 bp; e.g. Alu LINE: long interspersed element; 1000 bp;