protein-synthesis

PROTEIN SYNTHESIS

CENTRAL DOGMA OF MOLECULAR BIOLOGYDNARNA Protein transcriptiontranslation

GROWING CELL

Before cell division the cells DNA has to duplicate(DNA REPLICATION)While the cell is growing it needs enzymes and extra proteins

TRANSCRIPTIONTHE PROTEINS ARE MADE IN THE CYTOPLASM IN THE RIBOSOMESTHE INFO FROM THE DNA IS COPIED INTO m RNA, WHICH CAN LEAVE THE NUCLEUS AND GET TO THE RIBOSOMES IN THE CYTOPLASM.THE INFORMATION FOR PROTEIN SYNTHESIS IS IN THE DNA IN THE NUCLEUS.DNA INFO COPIED TO mRNA

TRANSCRIPTION: the processOnly 1 strand of DNA in a gene gets transcribed: RNA polymerase: enzyme that initiates transcription by binding to promoter at the 3' end of DNA, unwinds and unzips it.

RNA activated nucleotides pair with the complementary bases of the DNA strand RNA polymerase, binds the RNA nucleotides together to form the mRNA poynucleotide.

ANIMATIONhttp://207.207.4.198/pub/flash/26/transmenu_s.swf

CLIK here to view an animation of the whole process of transcription!

TRANSLATIONDNAM RNAPROTEINtranscriptionDNA info is copied into to RNA code, which is still in the language of nitrogenous bases, except that adenine on the DNA pairs with uracil (in place of thymine) on the RNA. HAPPENS IN NUCLEUS.translationThe RNA code is then translated to protein code, which is a different language. (nitrogenous bases to aminoacids. This process involves ribosomes and two kinds of RNA: mRNA and tRNA. HAPPENS IN CYTOPLASM

INFORMATION IN THE mRNACodon: sequence of 3 nucleotides on m-RNA that codes for one amino acid. The GENETIC CODE states which codon stands for which aminoacid.1 aminoacid1 aminoacid

GENETIC CODEEven though there are only 20 amino acids

that exist, there are actually 64 possible

tRNA molecules: 4 X 4 X 4 = 64 possible combinationsCODONCODONCODONG C U1 NUCLEOTIDE2 NUCLEOTIDE3 NUCLEOTIDE=Gly

GENETIC CODE (II)The GENETIC CODE can be reffered as well to the DNA, as in this case.How can you tell this GENETIC CODE reffers to DNA?Why can it be reffered to the DNA?

CHARACTERISTICS OF THE GENETIC CODE It can be reffered to DNA or RNA. It is UNIVERSAL. All living organisms share the same code.We can read the DNA of a bacterium, a plant or a worm using the same code!! PROOF FOR EVOLUTION!!! It is DEGENERATEAs there are ONLY 20 aminoacids but 64 possible codonsEach aminoacid has MORE than ONE codon! There are codons that code for punctuation (START and STOP)

TRANSLATIONLOADED tRNARIBOSOMEmRNACOMPONENTS PRESENT IN THE PROCESSanticodonAminoacid carriedcodon

TRANSLATIONThe newly made mRNA (transcription) leaves the nuceus and binds with the ribosome in the cytoplasm.ONE codon is exposed at site P and another codon at site AA tRNA with a complementary codon in its anticodon site will bind with the codon at site P, bringing an aminoacid.1 AMINOACID:Methionine (AUG) in site P.

TRANSLATIONEven though every protein begins with the Methionine amino acid, not all proteins will ultimately have methionine at one end. If the "start" methionine is not needed, it is removed before the new protein goes to work (either inside the cell or outside the cell, depending on the type of protein synthesized)

TRANSLATION2 AMINOACID: Glycine (only in this case) in site A.

PEPTIDIC BOND IS FORMED

TRANSLATIONSTOP codonNO aminoacid is added. Its the END of the polypeptide!Growing polypeptide

POLYSOMES

ANIMATIONhttp://ncc.gmu.edu/dna/ANIMPROT.htm CLIK here to view an animation of the whole process of translation!