Download protein synthesis

Biology
Unit 4B
Name: _______________________
GN#2: Protein Synthesis

Proteins are biomolecules that regulate cell processes.
o Examples: Enzymes, Transport Proteins, Hemoglobin
o Made of (Monomer) = Amino Acids assembled at a Ribosome

2 Steps to Make a Protein
o 1) DNA to mRNA  Transcription
o 2) mRNA to Protein  Translation
Transcription

DNA “rewritten” as mRNA….must be done because DNA is too large to leave the nucleus.
o Steps Involved
 1. Helicase enzymes unzip DNA by breaking hydrogen bonds between nitrogen bases
 2. RNA nucleotides are added to match the DNA template
 3. New mRNA detaches from the DNA template
 4. mRNA is edited to remove Introns (Junk DNA – don’t code for proteins) and leave
the Exons (Expressed DNA)
DNA
Intron


Pre-mRNA
mRNA
Exon
5. mRNA leaves the nucleus & travels to the ribosome
Practice the process of Transcription below
DNA
TAC GGA AGG TTT ACT
mRNA
Translation

mRNA used to determine Amino Acid sequence (Protein)
o Steps Involved
 6. mRNA attaches to ribosome
 7. Ribosome reads mRNA nucleotides in sets of 3
called a Codon
 8. A Start Codon (AUG) is found & amino acids are
delivered to ribosome by tRNA
 9. Amino acids are joined together with peptide bonds
until a Stop Codon (UGA, UAA, UAG) is found
 10. Assembled protein is released from ribosome,
folded & travels out into the cell to perform a specific
function
1
Genetic Code


Chart used to determine the amino acid written into the mRNA code.
Cross reference letters to determine the correct amino acid.
 Practice using
the genetic code to determine the correct amino acid sequence
DNA
TAC
GGA
AGG
TTT
ACT
mRNA
Amino Acid
2
You should be able to label the diagram above.
I
II
III
IV
V
What process is this?
Where does it happen?
3
4