Post on 19-Jan-2018
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Making Proteins:Translation
Lecture #25Honors Biology
Ms. Day
REVIEW…Translation
mRNA polypeptide (protein)
Type of RNA Function Job Picture
mRNA (messenger RNA)
Brings message from DNA (DNA instructions) to
ribosome to make protein
tRNA (transfer RNA)
Transfers/moves amino acids to
ribosomes
rRNA (ribosomal RNA)
Makes up ribosomes along
with proteins
tRNAA cell translates mRNA message into
protein with help from transfer RNA (tRNA)Each carries a specific amino acid“t” shapeCarries amino acidsMatches codons to anticodons
RibosomesHelp bind tRNA anticodons
with mRNA codons during translation
Anticodon (tRNA) = codon (mRNA)
tRNA(with
anticodons)
mRNA(with
codons)
AMINO ACIDS
REVIEW…The Genetic Code
It’s a table used that TRANSLATES RNA nucleotides called CODONS (or mRNA “letters”) into one of the 20 amino acids3 letter mRNA “word” = 1 amino acid
There are 4 different RNA “letters” that can be used
A, U, C, and G
THE GENETIC
CODE
RibosomesThere are 2 ribosomal subunits
Constructed of proteins and ribosomal RNA or rRNA
Building a PolypeptideTranslation can be divided into 3 phasesInitiationElongationTermination
Initiation of Translationinitiation stage brings
togethermRNAtRNA bearing 1st amino acid
(“start”) called MET2 subunits of a ribosome come
together
Large ribosomal subunit
Initiator tRNA
mRNA
mRNA binding site Smallribosomalsubunit
Translation initiation complex
GDPGTP
Start codon
Met MetU A C
A U G
3
5
5
3
35 35
Elongation Amino acids are added one by one
to the preceding amino acidPeptide bonds are formed
Amino acid
Termination of TranslationWhen the ribosome reaches a stop codon on the
mRNAThere are 3 stop codons
UAA, UAG, and UGARelease factor (protein) binds to stop codon (NOT tRNA)
polypeptide released
Termination of TranslationRelease factor Free
polypeptide
Stop codon(UAG, UAA, or UGA)
5
3 35
35
Figure 17.13
TRANSCRIPTION
TRANSLATION
DNA
mRNA
Ribosome
Polypeptide
Polypeptide
Aminoacids
tRNA with amino acid attachedRibosome
tRNAAnticodon
mRNA
Trp
Phe Gly
A G C
A A A
C C G
U G G U U U G G C
Codons5 3
“EMPTY”tRNA
Polypeptide 3D Protein Primary Structure
Amino acids is a row (LINEAR) Secondary Structure
Amino Acids BEND and FOLD towards each other
Tertiary Structure Amino acids BIND to each other 3D shape made
Quartnary structure (only some) 2 or more polypeptides BIND to
each other
1 2
3 4
Translation (Protein Synthesis) Animation
http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#
https://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__how_translation_works.html
http://www.biostudio.com/demo_freeman_protein_synthesis.htm