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Living Environment
Unit 5 Part 1: Is cancer in our genes?
Name: _______________________________________________________
Protein Synthesis
How are proteins synthesized?
DO NOW: Answer questions 1-4.
1. As an organism grows it often requires more copies of its DNA for new cells. Which of the following
processes is responsible for producing more DNA?
(1) Transpiration
(2) Replication
(3) Respiration
(4) Active Transport
2. Complete the DNA sequence below.
Strand 1
A T A T G G C C A
Strand 2
__________________
3. State the function of each organelle listed below:
 Nucleus: ____________________________________________________________________________
 Ribosome: ___________________________________________________________________________
4. Identify the building block of proteins. ________________________________________________________
Protein Synthesis
Step 1: Transcription
Step 2: Translation
The double stranded DNA code is used as a
template to create single stranded mRNA code.
The mRNA is a message that leaves the nucleus
and instructs the ribosome on how to make a
certain protein. mRNA is made up of nucleotides
like DNA but instead of having T’s it has U’s.
During translation the ribosome uses mRNA to
make a protein. Every 3 nucleotides in mRNA
(called a codon) is a code for a certain amino acid.
The ribosome “reads” the codons and puts the
corresponding amino acids together to make a
protein.
More about Transcription
During transcription DNA must be transcribed into a single stranded mRNA and sent to the ribosome. When
mRNA is made, base pairings change slightly…
THE SAME: T-A, C-G, C-G
DIFFERENT: A-U
Practice: Transcribe the DNA base sequences below into mRNA codons.
1. DNA Base Sequence
mRNA codon
T A T G G C A T T
_____ ______ ______
2. DNA Base Sequence
mRNA codon
A C T C T A A T G
_____ ______ ______
Think, Pair, Share: Why might it be better for the cell to make mRNA to send to the ribosome rather than
sending the DNA?
__________________________________________________________________________________________
__________________________________________________________________________________________
More about Translation
The second step in protein synthesis is called translation because the ribosome reads the mRNA codons and
“translates” the bases into amino acids, which is like a whole other language! To determine what amino acid
the mRNA codes for—simply look it up in the Universal Genetic Code chart!
Practice: Translate the mRNA codons into a chain of amino acids to make a protein!
mRNA codon - AUA-AGU-CAU-UUC-UGA
Amino Acids- ____ ____ ____ ____ ____
Compare & Contrast!
Process
Template
Replication
Product
Site
Purpose
Transcription
Translation
Practice Makes Perfect!!!!
With your partner:
1. Match the numbered stages with the correct lettered descriptions below
1. transcription ____
2. replication ____
3. translation ____
A) stage during which information coded in the base sequence of DNA is read to produce a strand of mRNA
B) process during which the genetic code in RNA is used to make proteins
C) process in which strands of DNA are separated and each is paired with nucleotides in order to form two
new strands of DNA
2. Fill in an mRNA codon that would code for each amino acid shown.
Amino acid:
GLU - PHE - TRP
mRNA codon: ______ ______ ______
3. Which three codons would code for a different amino acid sequence from that coded for by the mRNA base
sequence GGU-CGA-CUG
(1) GGU-AGA-CUG
(2) GGC-CGA-CUA
(3) GGU-CGU-CCG
(4) GGA-CGC-CUC
On your own:
1. Suppose you knew the makeup of specific proteins in a cell. How would you determine the particular DNA
code that coded for them? ____________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
2. Three structures are represented in the diagram below.
What is the relationship between these three structures?
(1) DNA is made up of proteins that are synthesized in the cell.
(2) Protein is composed of DNA that is stored in the cell.
(3) DNA controls the production of protein in the cell.
(4) The cell is composed only of DNA and protein.
3. Which of the following bases will not be present in a molecule of mRNA?
(1) Adenine
(2) Guanine (3) Uracil
(4) Thymine (5) Cytosine
4. What is the role of DNA molecules in the synthesis of proteins?
(1) They catalyze bond formation between amino acids.
(3) They supply energy for protein synthesis.
(2) They determine the sequence of amino acids in a protein (4) They transfer amino acids to the nucleus
5. The end result of the process of translation is the production of
(1)DNA
(2) Proteins
(3) RNA
(4) Inherited traits
6. The sequence of amino acids that makes up a protein is determined by the sequence of
(1) bases in DNA
(2) amino acids in DNA
(3) ribosomes in cytoplasm (4) glucose in the chloroplast
7. Base your answer to the question on the chart below, which represents a portion of the mRNA codon chart.
Complete the chart below with the mRNA codons and amino acids coded for by the DNA base sequence.
8. The sequence of bases below represents an entire strand of mRNA that is sent to the ribosome to construct
a protein. However, during translation, not every codon will result in an amino acid. In the spaces below,
write the first, second, and last amino acid that will appear in the protein.
CAU CGU AUG ACA AAU GAU UGA GCG
First AA ______
Second AA ______
Last AA _______
Name: _________________________________
Protein Synthesis
Homework Questions
1. The diagram below shows some steps in a cellular process. [2]
a. The section of DNA being used to make the strand of
mRNA is known as a
(1)
Carbohydrate
(3) Gene
(2)
Ribosome
(4) Chromosome
b. The process depicted is best described as
(1) Replication
(3) Translation
(2)Transcription
(4) Mutation
Turn over 
2. Some DNA, RNA, and amino acid information for three species of plants (A,B, and C) are shown below.
Using the information given, fill in the mRNA base sequence for species B and use the Universal Genetic Code
Chart in your notes, fill in the amino acid sequence for species C. [1]
Base your answers to questions 3-5 on the diagram below, which represents a sequence of events in a
biological process that occurs within human cells.
3. Molecule A contains the [1]
(1) starch necessary for ribosome synthesis in the cytoplasm
(2) organic substance that is broken down into molecules B, C, and D
(3) proteins that form the ribosome in the cytoplasm
(4) directions for the synthesis of molecules B, C, and D
4. Molecules B, C, and D are similar in that they are usually [1]
(1) composed of genetic information
(2) involved in the synthesis of antibiotics
(3) composed of amino acids
(4) involved in the diffusion of oxygen into the cell
5. Molecule A never leaves the nucleus. Instead, the cell uses a different molecule, molecule X to carry the
coded info contained in Molecule A to the ribosomes for processing. Molecule X is most likely: [1]
(1) DNA
(2) ATP
(3) mRNA
(4) DDT