2007-2008

12.3 PROTEIN SYNTHESISCornell notes

DNA-RNA-PROTEIN / what does RNA do?What does a scribe do? What does a translator do?What is the Central Dogma of Biology?

DNA

TRANSCRIPTION

TRANSLATION

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NUCLEUS CYTOPLASM

RNA

PROTEIN

copier

blueprints

TERMS TO REVIEW-genesegment of DNA contains genetic material-proteinbuilding blocks for all living things-amino acidsbuilding blocks of proteins-ribosomeorganelle helps manufacture protein-codon3 base code in DNA or RNA

MAIN IDEACENTRAL DOGMA:established BELIEF of living things

[foundation]transcription -DNA codes for RNAtranslation -RNA guides synthesis of PROTEINS

MAIN IDEATRANSCRIPTION

TRANSLATION

PROTEIN SYNTHESIS

TRANSCRIPTION/TRANSLATIONhttp://www.youtube.com/watch?feature=player_embedded&v=NJxobgkPEAoFrom RNA to Protein Synthesis - YouTube

LET’S REVIEWWhat is DNA?-deoxyribonucleic acidWhat N-base pairs make up DNA?cytosine=guanine /

adenine=thymineWhat happens during DNA replication?-2 new identical DNA strands

RNASIMILAR to DNA

-ribonucleic acid -sugar--RIBOSE

-guides protein synthesis-found in nucleus & cytoplasm-single stranded/different shapes-URACIL replaces thymine in RNA

A=U / C=G

RNA-RNA, like DNA is made of small units

called…

Made up of: -sugar (ribose) -phosphate group -N-bases

cytosine=guanine / adenine=uracil

NUCLEOTIDES

RNA

RNA [get out flip chart]3 MAIN types of RNA

mRNA -messenger RNArRNA -ribosomal RNA tRNA -transfer RNA

mRNAmessenger RNA-travels from nucleus to cytoplasm-direct synthesis of a specific protein-single strand formed w/DNA template

FLIP CHART PIC

rRNAribosomal RNA-cytoplasm-forms ribosomes in cytoplasm-ribbon shaped FLIP CHART PIC

tRNAtransfer RNA

-ribosomes in cytoplasm-transfer amino acids to ribosomes

-small segments of RNA nucleotides bent into cloverleaf shape

FLIP CHART PIC

TRANSCRIPTION1-DNA: RNA polymerase bind to

PROMOTERS2-DNA unzips-one strand acts as template

TRANSCRIPTION3-mRNA copy is made from DNA template strand

by RNA polymerase

4-mRNA copy is made until it reaches theTERMINATION (stop signal) sequence

5-mRNA strand leaves thru nuclear pores into cytoplasm to direct protein synthesis

6-5’ end of mRNA attaches to a ribosome in cytoplasm

TRANSCRIPTIONTEMPLATE vs NON-TEMPLATEONLY 3’-5’ strand serves as template

TRANSCRIPTIONhttp://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.htmlanimations

TRANSCRIPTION/ practice processing mRNA

Transcribe this DNA to mRNA

DNA- 5’GTACTACATGCTATGCAT3’

mRNA-3’CAUGAUGUACGAUACGUA5’

ADD cap 3’CAUGAUGUACGAUACGUA5’cap

-remove the introns “UGUA” and “AUAC”:

mRNA- 3’ CAUGAUGUACGAUACGUA 5’

-add poly-A tail onto the 3’ end 3’ CAUGACGGUA 5’Poly A

tailcap PROCESSED m RNA

THE CODEINSTRUCTIONS for PROTEIN synthesis

-mRNA is shorter than DNAintrons- sequences deleted, not in final mRNAexons- coding sequence remains in final mRNA

20 amino acids used to make proteins -each 3 base code is specific for an amino acid

codon- 3 base code in DNA or RNASTART codon- AUG-methionineSTOP codon- UAA, UAG, UGA

THE CODE

TRANSLATIONCODE is read -- TRANSLATED to make a PROTEIN

TRANSLATION1-tRNA acts as interpreters of mRNA codon2-tRNA folds into cloverleaf shape -activated by an enzyme -middle of tRNA is 3 base coding sequence- anticodon -each anticodon is complementary to codon on mRNA

TRANSLATION3-tRNAs add amino acids as move through

ribosome one codon at a time -3 base code determines protein to be made4-translation terminates when reach STOP codon

TRANSLATION

TRANSCRIPTION/TRANSLATION

PROTEIN SYNTHESIS

TRANSCRIPTION/TRANSLATIONhttp://www.youtube.com/watch?feature=player_embedded&v=NJxobgkPEAoFrom RNA to Protein Synthesis - YouTube

PROTEIN

PROTEIN STRUCTURE

PROTEIN