Transcript Protein Synthesis - Norman Public Schools

Protein Synthesis
Prior Knowledge

Protein: Large complex molecule that is essential to all
life
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Synthesis: to build, put together
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Protein Synthesis: building of proteins
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Proteins are made from amino acids
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Sequence of nucleotides code for specific proteins
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Enzymes are proteins which control the chemical reactions
in a cell
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DNA contains the codes therefore controls the cells.
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Ribosome: Place where proteins are assembled.
RNA
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Ribonucleic Acid
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“the workers”
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Take instructions from the DNA and build the proteins one amino acid
at a time.
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Single Stands
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Sugar is Ribose
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Bases: Adenine, Uracil (pairs with Adenine), Guanine, Cytosine
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Three Types:
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mRNA
tRNA
rRNA
Types of RNA
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Messenger RNA (mRNA)
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Ribosomal RNA (rRNA)
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Brings the DNA’s instructions from the nucleus to the
cytoplasm to the ribosome.
Binds to mRNA and uses the instructions to assemble
amino acids.
Transfer RNA (tRNA)
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Brings amino acids to the ribosome to be assembled.
Transcription
First step in the Protein Synthesis method
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DNA Helicase unzips the DNA
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Free RNA nucleotides pair with complimentary bases.
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A to U; C to G
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One portion of DNA is copied.
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RNA nucleotides bond together and form *ONE mRNA
strand.
* Different in DNA replication…two new strands are formed in DNA
replication.
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mRNA strands leaves the nucleus and heads to the ribosomes.
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DNA strands reconnect.
Genetic Code
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mRNA contains a code using A’s, U’s, C’s, G’s.
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Complete instructions for building a protein
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Code must be converted into protein language
Genetic Code
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Codon: group of THREE nitrogenous bases code for ONE
amino acid.
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Ex: UUU codes for Phenylalanine to be placed into a protein.
Ex: UAA is a stop codon
Ex: AUG is a start codon
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64 combo’s are possible
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More than one codon can code for one amino acid
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UAU & UAC are both Tyrosine codons
One Codon only codes for 1 amino acid
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UAU only codes for Tyrosine
UCU only codes for Serine
Genetic Code
ALL ORGANISMS USE
SAME GENETIC CODE!!!
First Base in Codon: C
Second Base in Codon: A
Third Base in Codon: U
So…CAU codes for
His (Histidine)
What does UAG code for?
Stop
What does AGC
code for?
Serine
DNA Code:
mRN Strand
Protein
T A C /A C G /A T A/G T G /A T T
AUGUGCUAUCAC UAA
Start
Cystine Tyrosine
Histidine
Stop
Translation
Second Step in Protein Synthesis
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Occurs at the ribosomes
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Ribosome attaches to mRNA like a clothespin
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Sequence of bases is converted into sequence of
amino acids
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Use Genetic Code
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Ex: CAU to Histidine
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Ex: UAG to Stop etc…
tRNA brings needed amino acids to the ribosome to
build the protein.
Translation
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tRNA has two sides
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amino acid side
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Nitrogenous base side
Anticodon: 3 bases of tRNA
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on opposite end of amino
acid
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Pair up with mRNA bases
What is the anticodon for the following mRNA strand?
AUG
UAC
Translation
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Amino acids bond with each other
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Forms polypeptide bonds or PROTEINS!!
This Process continues until a STOP codon is
reached