文档介绍：Techniques of Molecular Biology
Chapter 20
OUTLINE
Introduction()
Nucleic Acids()
Proteins()
INTRODUCTION
Understanding how the ic processes of the cell work requires powerful,plementary experimental approaches including the use of suitable anisms in which the tools of ic analysis are available.
Methods for separating individual macromolecules from the myriad mixtures found in the cell,and for dissecting the genome specific DNA sequences
putational putational or bioinformatics approaches,to undertake large-scale parisons of both the cosing and noncoding regions of anisms.
The methods of molecular biology depend upon,and were developed from,an understanding of the properties of biological macromolecules themselves.
A NOTE:
It is important to appreciate that when we talk about isolating and purifying a given macromolecule in the ensuing discussion we rarely mean that a single molecule is ,the goal of these procedures is to isolate a large population of identical molecules from all of the other kinds of molecules in cell
NUCLEIC ACIDS
This part is devoted to techniques for the manipulation and characterization of nucleic acids,from the isolation of RNAs and DNAs to the sequencing of entire genomes parative genomics.
Electrophoresis through a Gel separates DNA and RNA Molecules According to Size
Gel electrophoresis (凝胶电泳) separation of DNA and RNA DNA molecules separate according to size when subject to an electric field through a gel matrix(an inert,jello-like porous material)动画
DNA molecules are flexible and occupy an effective volume pores in the gel matrix sieve the DNA molecules according to this volume;large molecules migrate more slowly through the gel because they have a larger effective volume than do smaller DNAs,and thus have more difficulty passing through the interstices of the gel.
Different sizes are separated because they moved different distances through the gel.