The Central Dogma of Molecular Biology Land of Mayo：分子物学的中心教条地梅奥

1、the central dogma of molecular biologymark mayocypress collegelast update 10/6/13the central dogma of molecular biologyreversetranscriptionimportance of proteins nthere are three main kinds:insulin, a proteinimportance of proteins nwithout proteins there would be no lifenall cells make proteinsnprot

2、eins in your body make up your:discovery of dna (deoxyribonucleic acid) n1953 watson, crick and wilkins determined the structure of dna to be a double helixnthey won a nobel prize for their work structure of the dna molecule ndna is shaped like a double helixnit is like a spiral staircasenanother wa

3、y to think of it is a twisted ladderconnecting the dna moleculenrails of the dna ladder are alternating sugar & phosphatesnrungs are composed of pairs of basesconnecting the dna moleculenthe dna ladderps aps tps gps - c pt - s pa - s pc - s pg - sps aps tp? gps - c pt - ? p? - s pc - s pg - scon

4、necting the dna moleculenthe two strands of dna are differentnone is called the sense strand and it is the plan to make a proteinnthe other strand is the antisense strand and it is only used for protection of the sense strandconnecting the dna moleculenthe two strands of dna are said to be antiparal

5、lelnone strand is oriented in a 5 to 3 directionnthe other strand is oriented in the opposite 3 to 5 direction5 33 5senseantisenseconnecting the dna moleculennucleotides are units composed of abase, phosphate and a sugar connecting the dna moleculenthe two strands of dna bases are connected by weak

6、forces called hydrogen bonds components of dna nphosphate components of dnandeoxyribose (sugar) components of dnandna bases (4 different types)components of dnanproteins are attached to the dna helix in cellsnthese proteins are known as histones nthey assist in dna storagedna and rna compared ndna n

7、rna* dna is also found in a select number of other organellesreplication of dna nreplication - the making of an exact copy of the dna moleculereplication of dnastages in replication (basic)ndna molecule is split in two at the end by the work of enzymes ndna unzips slightly and the two strands unwind

8、 nnew nucleotides attach to the free ends ( a-t, g-c)nmore dna unzipsnmore nucleotides attach nprocess continues until completednresult is two (2) double strands of dnaneach strand is 50% new and 50% old dnastages in replicationndna replication is different on the leading and lagging strands nlaggin

9、g strand has okazaki fragmentsstages in replicationndna replication is different on the leading and lagging strands enzymes involved in dna replicationndna polymerase adds nucleotides in a 5 to 3 directionntopoisomerasengyrasenrna primasendna ligase connects the gaps in the lagging stranddna replica

10、tionin motionintrons and exonsnintrons sequences in the dna that are not used to make mrna or to make a protein. they are not transcribed nexons sequences in the dna that are expressed or used to make mrna and ultimately are used to make a proteinintrons and exonsrestriction enzymesnrestriction enzy

11、mes (also known as restriction endonucleases) recognize specific dna sequences and cleave or cut the dna into pieces ngenerally these cuts occur in a manner which leaves a sticky end of single strand dnanthese pieces can be separated by using gel electrophoresis (this is like electronic chromatograp

12、hy)nwe use restriction enzymes for cutting bacterial, viral or even human dna and later insertion of the desired dna fragments called gene splicing restriction enzymessticky endssticky endsblunt endsblunt endsrestriction enzymesribonucleic acid (rna)nthree types of rna:ribonucleic acid (rna)nribosom

13、al rna is used to make a ribosomenthe ribosome “reads” the mrna plan for the new proteinnmrna is the set of directions for a new proteinribonucleic acid (rna)nmessenger rnasenseantisenseribonucleic acid (rna)ntransfer rnaribonucleic acid (rna)ntransfer rnatranscription ntranscription is the special

14、copying of one side of the dna molecule (the sense strand) that results in the production of a single strand of rna nthe original dna is not changednthis process can be repeatednthe amount of dna that is transcribed is usually one genethe r in the title is red to remind you that transcription makes

15、rnatranscriptionnprocess of transcriptiontranscriptiontranscriptionnuracil a base only found in rnatranscriptionntranscription practice transcriptiontranscriptionsometimes two or more ribosomes attach to the mrna transcript at the same time and this is called a polysome translationntranslation is th

16、e reading of the rna code, by ribosomes, to make proteins or polypeptides ntranslation is often called protein synthesistranslationnmrna is the message (the plan for the protein)nrrna reads the mrna (the ribosome) ntrna molecules carry amino acids to the ribosome for assembly into proteinsnthe ribos

17、ome allows only the correct trna to add its amino acid others are rejectedtranslation anticodons codons translationtranslationntriplet codons -groups of three bases on mrna that code for specific amino acids translationnthe function of special stop codons is to terminate or end the translation processnthe stop codons are: uaa, uag and ugatranslationn9 bases would give _?_ amino acids n27 bases would give _?_ amino acids translationnanticodon practice translationcentral dogma practiceantisense dnasense dnamrnaproteina t g g g g c c c t t t a a a g g c t a acentral dogma pra