Chapter 2 From genes to genomes 莘大
Chapter 2 From Genes to Genomes
2.1Introduction We can think about mapping genes and genomes at several levels of resolution A genetic (or linkage) map identifies the distance between mutations in terms of recombination frequencies A linkage map can also be constructed by measuring recombination between sites in genomIc NA A restriction map is constructed by cleaving DNA into fragments with restriction enzymes and measuring the distances between the sites of cleavage The ultimate map is to determine the sequence of the DNA From the sequence, we can identity genes and the distances between them 消当
2.1 Introduction We can think about mapping genes and genomes at several levels of resolution: A genetic (or linkage) map identifies the distance between mutations in terms of recombination frequencies. A linkage map can also be constructed by measuring recombination between sites in genomic DNA. A restriction map is constructed by cleaving DNA into fragments with restriction enzymes and measuring the distances between the sites of cleavage. The ultimate map is to determine the sequence of the DNA. From the sequence, we can identify genes and the distances between them
2.1 Introduction 2.2 The nature of interrupted genes 2.3 Organization of interrupted genes may be conserved 2. 4 EXon sequences are conserved but introns vary 2.5 Genes can be isolated by the conservation of exons 2.6 Genes show a wide distribution of sizes 2. 7 Some DNA sequences code for more than one protein 2. 8 How did interrupted genes evolve? 2. 9 The scope of the paradigm 消当
2.1 Introduction 2.2 The nature of interrupted genes 2.3 Organization of interrupted genes may be conserved 2.4 Exon sequences are conserved but introns vary 2.5 Genes can be isolated by the conservation of exons 2.6 Genes show a wide distribution of sizes 2.7 Some DNA sequences code for more than one protein 2.8 How did interrupted genes evolve? 2.9 The scope of the paradigm
2.2 Genes can be mapped by restriction cleavage bp is an abbreviation for base pairs, distance along DNA IS measured in bi Restriction enzymes recognize specific short sequences of DNA and cleave the duplex (sometimes at target site, sometimes elsewhere depending on type) Restriction map is a linear array of sites on DNA cleaved by various restriction enzymes 消当
bp is an abbreviation for base pairs; distance along DNA is measured in bp. Restriction enzymes recognize specific short sequences of DNA and cleave the duplex (sometimes at target site, sometimes elsewhere, depending on type). Restriction map is a linear array of sites on DNA cleaved by various restriction enzymes. 2.2 Genes can be mapped by restriction cleavage
2.2 Genes can beCleave with Cleave with enzym enzyme B mapped by restriction cleavage Electrophorese Electro phorese Electrophorese A-fragments control dNa B-fragments FIgure 21 DNA can be 2500 2500 2100 cleaved by restriction 1400 enzymes into fragments 1000 1=18 500 50 that can be separated by gel electrophoresis Fragment sizes Control consists Fragment sizes 消当 compared of frag ments compared with control of known size with contr ol
Figure 2.1 DNA can be cleaved by restriction enzymes into fragments that can be separated by gel electrophoresis. 2.2 Genes can be mapped by restriction cleavage
2.2 Genes Individual ndividual Total DNA A-fragments B-fragments digeste 已 can be are digested are digested w ith both with enzymes with enzyme a enzymes mapped by吕吕 吕吕吕 restriction xx cleavage ↓ Flgure 22 Double digests define the cleavage positions 000 of one enzyme with 哥卧国 600 regard to the other 50 消当
Figure 2.2 Double digests define the cleavage positions of one enzyme with regard to the other. 2.2 Genes can be mapped by restriction cleavage
A-2100—) The A-2100 2.2 Genes can fragm ent identifies 2 ing sites& 1 B-cutt ing site be mapped by 1900 restriction 21 A-digest fragments cleavage Double 2:P with the fragment Figure 2 3 1900 B B-digest fragments/ to the right map A restriction map can be A A constructed by Overlap with日 1200 extends m elating the A 分 o left; overlap 6“少 A-1400extends map to right fragments and B 72U 2500 fragments through the overlaps seen 700A Left end of map is with double digest identi fied by A- fragments ←-1005←m1个 fragm ents right end is identi fed by z0…>B-2500 →)Be-10→ A-500and日-1300 消当
Figure 2.3 A restriction map can be constructed by relating the Afragments and Bfragments through the overlaps seen with double digest fragments. 2.2 Genes can be mapped by restriction cleavage
2.2 Genes can be mapped by restriction cleavage 圆用< tion ma restriction fragments are identified by fragments identified on gel their possession of AG〔 broken labeled end. each HA-B-C-D-E E-F fragment directly shows the distance 目CBE of a cutting site A-B-C from the end A-日 Successive 凸 Fragments Increase In length by the distance between diacent restriction Labeled end sites 消当
Figure 2.4 When restriction fragments are identified by their possession of a labeled end, each fragment directly shows the distance of a cutting site from the end. Successive fragments increase in length by the distance between adjacent restriction sites. 2.2 Genes can be mapped by restriction cleavage
2.2 Genes can be mapped by restriction cleavage 10020190060805( Figure 2.5 A restriction map is a linear sequence of sites separated by defined distances on DNA. The map identifies the sites cleaved by enzymes A and B, as 请菲大 ned by the individual fragments produced by the single and double digests
Figure 2.5 A restriction map is a linear sequence of sites separated by defined distances on DNA. The map identifies the sites cleaved by enzymes A and B, as defined by the individual fragments produced by the single and double digests. 2.2 Genes can be mapped by restriction cleavage
2.3 How variable are individual genomes? Haplotype is the particular combination of alleles in a defined region of some chromosome. in effect the genotype in miniature. Originally used to described combinations of MHC alleles. it now may be used to describe particular combinations of RFLPS SNP (sIngle nucleotide polymorphism) Is any site at which a single nucleotide has changed when two (haploid) genomes are compared 消当
Haplotype is the particular combination of alleles in a defined region of some chromosome, in effect the genotype in miniature. Originally used to described combinations of MHC alleles, it now may be used to describe particular combinations of RFLPs. SNP (single nucleotide polymorphism) is any site at which a single nucleotide has changed when two (haploid) genomes are compared. 2.3 How variable are individual genomes?
