dna transcription & protein translation. today’s objectives introduce protein synthesis...
Post on 13-Dec-2015
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3 Main Differences from DNA
1. RNA has one strand of nucleotides
2. RNA has ribose as it’s sugar
3. RNA has Uracil as a nitrogen base instead of thymine (U bonds with A)
Three Classes of RNA
Messenger RNA mRNA
Carries the “blueprint” for protein assembly to the ribosome
Transfer RNA
tRNA Brings the correct amino acid to the ribosome
and pairs up a mRNA code for that amino acid
Codon-A series of 3 bases that code for an amino acid Located on the mRNA strand
Anti-Codon-a triplet of nucleotides in transfer RNA that is complementary to the codon in messenger RNA which specifies the amino acid
Located on the tRNA molecule
DNA Transcription
DNA must be copied to messenger RNA (mRNA)
mRNA goes from nucleus to the ribosomes in cytoplasm
mRNA complements known as codons– Only 3 nucleotide “letters” long
Remember RNA has uracil (U) instead of thymine (T)!
Transcription – Step II
A C G T A T C G C G T A U G C A U A G C G C A U
Template DNA is Matched Up with Complementary mRNA Sequences
Transcription Reminders
The template strand is the DNA strand being copied
The rRNA strand is the same as the DNA strand except Us have replaced Ts
Protein Translation
Modified genetic code is “translated” into proteins
Codon code is specific, but redundant!– 20 amino acids– 64 triplet (codon) combinations
Using the Codon Table
learn how to use a codon table to translate mRNA into its associated amino acids
Let’s Play Bingo!!
tRNA structure
3-base code (triplet) is an “anticodon” Protein molecule Attached amino acid that is carried from
cytoplasm to ribosomes
Protein Synthesis
Start: Ribosome binds to mRNA at start codon (AUG)
Elongation: – tRNA complexes bind to mRNA codon by forming
complementary base pairs with the tRNA anticodon– The ribosome moves from codon to codon along the
mRNA. – Amino acids are added one by one
Release: release factor binds to the stop codon
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