1. Introduction and Overview
PROTEIN SYNTHESIS
Introduction and Overview

2. How DNA directs how proteins are made
Protein Synthesis
How DNA directs how proteins are made

3. The variety of life on earth is due to different proteins.

4. Protein Synthesis
You are different from the people around you because your proteins are different.

5. Your hair, muscles fibres in your skin are all made of proteins.
Protein Synthesis
Your hair, muscles fibres in your skin are all made of proteins.

6. Protein Synthesis
If you have straight hair, your protein is slightly different to someone who has curly hair

7. Protein Synthesis Proteins are made up of units called amino acids
In our examples we will use a few amino acids to represent a protein
Proteins are much larger and have more that 50 amino acids

8. Protein Synthesis Proteins are made up of units called amino acids.
Amino acids join together to make proteins.

9. Protein Synthesis
Proteins differ from each other by the type (different shapes) and sequence (the order in which the shapes occur) of amino acids.
If this is the protein for straight hair
A single amino acid change results in curly hair

10. Protein Synthesis
The proteins are different because the DNA for curly and straight hair is different. There is a THREE letter DNA code (codon) for each amino acid. Eg. TGG codes for

11. Protein Synthesis AGC codes for a GGT codes for a
In this example: TAC codes for a AAA codes for a
The code for this amino acid sequence is :
What is the DNA code for this sequence?
TAC
AGC
GGT
AAA GGT GGT

12. Protein Synthesis: Overview of the Process
DNA
RNA
Protein C G T A G C A U
makes
makes

13. Protein Synthesis: A closer look
Firstly, part of the DNA is copied into messenger RNA (mRNA) This is called TRANSCRIPTION

14. Protein Synthesis: A closer look
The mRNA carries the message to make the protein to the cytoplasm and attaches to the ribosome

15. Protein Synthesis: A closer look
tRNA collects amino acids in the cytoplasm

16. Protein Synthesis: A closer look
TRANSLATION: tRNA brings amino acids to the ribosome which link and form proteins

17. Protein Synthesis
The Detailed Process

18. A piece of DNA that codes for a protein is copied into mRNA
TRANSCRIPTION
A piece of DNA that codes for a protein is copied into mRNA

19. Part of the DNA molecule is unzipped by an enzyme
TRANSCRIPTION
Part of the DNA molecule is unzipped by an enzyme

20. TRANSCRIPTION
DNA separates

21. A piece of DNA from one side is copied into mRNA
TRANSCRIPTION T A A U
A piece of DNA from one side is copied into mRNA C G A U A U A U A U G C C G G C G C T A

22. mRNA separates from DNA
TRANSCRIPTION
mRNA separates from DNA T A C G U A C A A A A U G C A G C G G T

23. T A C G A U G C

24. mRNA moves out of the nucleus to a ribosome in the cytoplasmG A U G C
ribosome

25. mRNA attaches to a ribosomeU G C A U G C

26. The ribosome encodes mRNA to form a new protein
TRANSLATION
The ribosome encodes mRNA to form a new protein

27. tRNA brings a specific amino acid which links mRNAU A C
tRNA A U G C
mRNA

28. Corresponding tRNA code (anticodon) mRNA three letter code (codon)
The tRNA with its specific amino links to mRNA according to its specific three letter code
Amino Acid U A C
tRNA A U G C
mRNA
Corresponding tRNA code (anticodon)
mRNA three letter code (codon)

29. tRNA brings in the next amino acid according to the next mRNA codon U A C A
tRNA brings in the next amino acid according to the next mRNA codon
tRNA moves into the cytoplasm to collect another amino acid
The ribosome moves along the mRNA molecule exposing the next codon U A C
The amino acids combine A U G C

30. tRNAs bring in another amino acids to extend the protein chainU G C
The process continues as the ribosome moves along mRNA exposing the next codon

31. tRNAs bring in another amino acids to extend the protein chainU A G C A U G C
The process continues as the ribosome moves along mRNA exposing the next codon

32. TERMINATION: Ribosome and mRNA separate NEW “Protein” is formedG U
NEW “Protein” is formed A U G C

33. In Summary … T A C G
DNA
makes A U G C
RNA
makes
Protein