DNA is a double stranded helixcomposed of A-T and G-Ccomplementarybases.5Fig.1.21-11
1-11 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Fig. 1.2 DNA is a double stranded helix DNA is a double stranded helix composed of A composed of A-T and G T and G-C complementary bases. complementary bases
Genes are seguences of DNA that encode proteins andRNAs.DNA-GTACTAGTGGTGGAGAGAGCGGCATATTAAARNAATGGCATCAACTGCTCCC AAT GAATAGCGCTATCCTCGGTTC--Protein1-12
1-12 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Genes are sequences of DNA that encode proteins and are sequences of DNA that encode proteins and RNAs . 5’-GTACTAGTGGTGGA GAGAGCGGCATATTAAA ATG GCA TCA ACT GCT CCC AAT GAA- TAG CGCTATCCTCGGTTC- -3’ DNA RNA Protein
Order of nucleotide seguences determines which proteins aresynthesized, as well as when and where the synthesis occurs.(a)Proline?Threonine中UTwo amino acidDNA:ComplementaryRNA:Single strandstrandscomplementarysubunits ofato DNA strandproteinon the rightFig.1.5a1-13
1-13 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Fig. 1.5a Order of nucleotide sequences Order of nucleotide sequences determines which proteins are determines which proteins are synthesized, as well as when and where the synthesis occurs. synthesized, as well as when and where the synthesis occurs
Genetic information is digitalThe seguence of bases in DNAcan be read by DNA sequencers,stored in computers,andsynthesized by DNA synthesizers1-14
1-14 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Genetic information is digital Genetic information is digital The sequence of bases in DNA The sequence of bases in DNA can be read by DNA sequencers, can be read by DNA sequencers, stored in computers, and stored in computers, and synthesized by DNA synthesizers. synthesized by DNA synthesizers
DNA resides within cellsChromosomebdChromaficpackaged as units calledNucleuTelamerechromosomesLaCentromereHumans have23pairs ofchromosomes.CellThe entire collection ofgenetic information in acell is called genomeBase PairThe human genome hasabout3×109basepairsBHSand20,000-30,000genes1-15
1-15 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display DNA resides within cells DNA resides within cells packaged as units called packaged as units called chromosomes chromosomes Humans have 23 pairs of Humans have 23 pairs of chromosomes. chromosomes. The entire collection of The entire collection of genetic information in a genetic information in a cell is called cell is called genome . The human genome has The human genome has about 3 about 3 10 9 base pairs base pairs and 20,000 and 20,000 – 30,000 genes. 30,000 genes