Name___________________________
Date_________________
Period_____
Protein Synthesis
(A) GENES AND PROTEINS
 DNA contains information used to make proteins
 Proteins determine our genes
 All of the information contained in our genes is based on the sequence of
nucleotides in the DNA molecule.
(B) TYPES OF RNA
o RNA serves as a temporary copy of DNA and delivers the infomation
on how to make proteins to the ribosomes
o
mRNA: ______________________________________________
________________________________________________________
o
rRNA: _______________________________________________
________________________________________________________
o
tRNA: _______________________________________________
________________________________________________________
mRNA
tRNA
(C) PROTEIN SYNTHESIS
o
Protein Synthesis is ___________________________________
_______________________________________________.
It occurs in the ___________________________. (THINK: Where is the DNA?)
o
Protein Synthesis occurs in two steps:
 Transcription
 Translation
1-TRANSCRIPTION
o mRNA is made during transcription
o Why?
1)_________________________________________________________
2)___________________________________________________
o
Process: This process involves the use of enzymes, particularly
RNA Polymerase.
 A)________________________________________________

RNA Polymerase knows where to bind on the DNA due to
spots on the DNA called promoters, which act as start point
signals for transcription.

B)________________________________________________
________________________________________________

***Remember there is no thymine is RNA. So, uracil pairs
with adenine when making mRNA.***

C)________________________________________________
________________________________________________

D)________________________________________________
________________________________________________

E) mRNA leaves the nucleus and goes into the cytoplasm
2-RNA Editing: In eukaryotes Transcription is not done until the RNA is edited.
The RNA is made of 2 parts:
a. Introns (junk)
b. Exons (codes for the protein)
The introns must be removed so that the right protein is made!
The remaining exons are spliced together to make a single, mature mRNA.
(D) THE GENETIC CODE
o
The nucleotide sequence transcribed from DNA to a strand of mRNA is
a genetic message that has ALL the information needed to build a
protein.
o
The message is in a special language that uses nitrogenous bases as
the alphabet.
o
The amino acids that make up proteins are made from only four
nitrogenous bases.
o
The information on the DNA is read as CODONS.
o
Codon:
________________________________________________________________
____________________________________________
o
There is even a codon that tells the mRNA to start and another to stop
making the protein.
o
The genetic code is read using the following chart:
G-U-C: G- First position
U- Second position
C- Third position
Read the chart from the inside out!!
LET’S PRACTICE:
A-U-G _________________
C-U-A ________________ G-A-C ______________
G-G-U _________________
U-G-A ________________ A-A-C _______________