Protein synthesis

1. PROTEIN SYNTHESIS
The Protein-making Process

2. Protein Synthesis (Gene Expression) Notes
Proteins (Review)
• Proteins make up all living materials

3. • Proteins are composed of amino acids – there are 20
different amino acids
• Different proteins are made by combining these 20
amino acids in different combinations

4. • Proteins are manufactured (made) by the ribosomes

5. •Function of proteins:
1. Help fight disease
2. Build new body tissue
3. Enzymes used for digestion and other chemical
reactions are proteins
(Enzymes speed up the rate of a reaction)
4. Component of all cell membranes

6. MAKING PROTEINS
Step 1:Transcription

7. Making a Protein—Transcription
•First Step: Copying of genetic information from DNA to
RNA called Transcription
Why? DNA has the genetic code for the protein that
needs to be made, but proteins are made by the
ribosomes—ribosomes are outside the nucleus in the
cytoplasm.
DNA is too large to leave the nucleus (double stranded),
but RNA can leave the nucleus (single stranded).

8. • Part of DNA temporarily unzips and is used as a
template to assemble complementary nucleotides
into messenger RNA (mRNA).

9. • mRNA then goes through the pores of the nucleus with
the DNA code and attaches to the ribosome.

10. MAKING PROTEINS
Step 2:Translation

11. Making a Protein—Translation
• Second Step: Decoding of mRNA into a protein is called
Translation.
• Transfer RNA (tRNA) carries amino acids from the
cytoplasm to the ribosome.

12. These amino acids come from the food we eat. Proteins
we eat are broken down into individual amino acids and
then simply rearranged into new proteins according to the
needs and directions of our DNA.

13. •A series of three adjacent bases
in an mRNA molecule codes for
a specific amino acid—called a
codon.
•Each tRNA has 3 nucleotides
that are complementary to the
codon in mRNA.
•Each tRNA codes for a different
amino acid.
Amino acid
Anticodon

14. • mRNA carrying the DNA instructions and tRNA carrying
amino acids meet in the ribosomes.

15. • Amino acids are joined together to make a protein.
Polypeptide = Protein

16. Individual Activity: Decoding
Directions:
1. Fill in the complementary DNA Strand using DNA
base pairing rules.
2. Fill in the correct mRNA bases by transcribing the
bottom DNA code.
3. Translate the mRNA codons to find the correct
amino acid using the Codon table.
4. Write in the amino acid and the correct anti-
codon the tRNA molecule.

18. AGG CGC GTC TCG ATC
DNA Parent Strand
DNA Complementary Strand
mRNA
tRNA
Amino acid

19. Use one of the codon charts on the next page to find the amino acid
sequence coded for by the following mRNA strands.
CAC/CCA/UGG/UGA
___________/___________/___________/____________
AUG/AAC/GAC/UAA
___________/___________/___________/____________

20. CAC/CCA/UGG/UGA
___________/___________/___________/____________
1
st
Base
2nd Base
3
rd
Base
Histidine` Proline Tryptophan Stop

21. AUG/AAC/GAC/UAA
___________/___________/___________/____________
Methionine Asparagine Aspartic Acid Stop

22. Protein Synthesis

23. AUG – is the start codon
Stop Codons
Stop codons tells the
ribosomes …
UGA – U Go Away
UAA – U Are Away
UAG – U Are Gone

26. The Dance of Translation
In the bustling cell, a dance takes place,
A wondrous process, a molecular embrace.
mRNA, the messenger, carries the code,
From DNA's nucleus, it begins to unfold.
G:

27. The Dance of Translation
The ribosomes, the stage where it all occurs,
Protein synthesis, a dance that never blurs.
mRNA arrives, with its instructions in tow,
Ready to create proteins, a vital show.
B:

28. The Dance of Translation
Initiation begins, the small subunit awaits,
mRNA moves, the large subunit mates.
AUG, the start codon, signals the start,
The ribosome is ready, playing its part.
G:

29. The Dance of Translation
Elongation commences, the ribosome moves,
Reading each codon, the dance it approves.
tRNA, the partner, brings amino acids near,
Matching codons with anticodons, crystal clear.
B:

30. The Dance of Translation
Peptide bonds form, a chain starts to grow,
Amino acids join, a protein begins to show.
The ribosome glides, along the mRNA strand,
Creating a masterpiece, as it takes a stand.
G:

31. The Dance of Translation
Termination arrives, a stop codon is found,
The dance comes to an end, with a graceful sound.
A release factor joins, the polypeptide is complete,
The ribosome releases, the protein is now concrete.
B:
Oh, the beauty of translation, this intricate dance,
mRNA to proteins, a molecular romance.
In the cell's grand theater, this process unfolds,
Creating the proteins that life truly holds.

32. The Dance of Translation
So let us marvel at this dance so grand,
The translation of mRNA, a masterpiece planned.
For in the world of cells, this dance is key,
Creating the proteins that make us truly be.
G:

33. Guide Questions:
1. What is the role of mRNA in the process described
in the poem?
2. What is the function of the ribosomes in protein
synthesis?
3. How does the process of initiation begin in the
poem?
4. What is the role of tRNA in the dance of
translation?
5. How does the poem describe the importance of
protein synthesis in living organisms?

34. Directions: Use the genetic code chart provided to translate
the following mRNA sequences into their corresponding
amino acid sequences. Write the amino acid sequence in the
space provided.
mRna sequence AUG UCG CAA UAA
Amino acid
sequence
mRna sequence UUU GGC ACU AGC
Amino acid
sequence
mRna sequence GCU AAA UGG UCU
Amino acid
sequence
mRna sequence UAC CCG AGU GAA
Amino acid
sequence