1. PROTEIN SYNTHESIS

2. WHAT YOU NEED
TO MAKE PROTEINS
DNA = instructions to make the protein
Amino acids = parts that make up proteins
RNA = “workers” to help assemble the “parts”

3. Amino acids are the building blocks (monomers) of proteins
PROTEIN SYNTHESIS
Amino acids are the building blocks (monomers) of proteins
The sequence of nucleotides in each gene contains information for how to assemble a chain of amino acids that make up a single protein
***(one gene, one protein)***

4. Nucleic Acids DNA RNA Double-stranded Sugar = deoxyribose Thymine = T
Single-stranded
Sugar = ribose
Uracil = U

5. RNA Messenger RNA (mRNA) 2. Ribosomal RNA (rRNA)
Take info from DNA in nucleus to cytoplasm (factory floor)
2. Ribosomal RNA (rRNA)
Assemble amino acids in correct order
3. Transfer RNA (tRNA)
Transports amino acids to the ribosome to be assembled into protein

6. 1. TRANSCRIPTION: DNA  mRNA PROTEIN SYNTHESIS
In the nucleus, enzymes make an RNA copy of part of a DNA strand (similar to DNA replication)
DNA  mRNA

7. 1. TRANSCRIPTION: FROM DNA to mRNA
PROTEIN SYNTHESIS
1. TRANSCRIPTION: FROM DNA to mRNA
RNA is like DNA except
A pairs with U, not T
THERE IS NO T IN RNA!
For example:
DNA: C T C A G G A T
mRNA: G A G U C C U A
Now do your example:

8. 1.TRANSCRIPTION: DNA  mRNA PROTEIN SYNTHESIS DNA: ATC CGA ATG GTA
mRNA: UAG GCU UAC CAU
DNA  mRNA
Once mRNA has copied a strand of DNA, it now LEAVES THE NUCLEUS and moves to the RIBOSOME where the protein will be made!

9. Quick Review Transcription What is happening? Where in the cell?
Which types of nucleic acids are involved, DNA, RNA, or both?
What is the purpose of producing an RNA copy of the code in DNA?
What part of the cell produces proteins?

10. 2. TRANSLATION: from mRNA to Protein
PROTEIN SYNTHESIS
2. TRANSLATION:
Takes place at ribosomes so proteins can be made
from mRNA to Protein

11. PROTEIN SYNTHESIS 20 amino acids mRNA has only 4 bases (A, U, C, G)
Message is read 3 nucleotides of mRNA at a time
CODON = 3 mRNA nucleotides
Examples:
U-U-U A-G-C U-G-C

12. PROTEIN SYNTHESIS A gene codes for a A codon codes for an PROTEIN
AMINO ACID

13. PROTEIN SYNTHESIS
Not all codons code for amino acids
Key Codons:
AUG = start codon
UAA = stop codon

14. 2. TRANSLATION: from mRNA to Protein
PROTEIN SYNTHESIS
2. TRANSLATION: from mRNA to Protein
Takes place at ribosomes in cytoplasm
tRNA brings amino acids through cytoplasm to ribosomes
Each tRNA attaches to only one type of amino acid
Anticodon (tRNA) pairs with codon (mRNA)

15. CODON
tRNA

16. TRANSLATION: from mRNA to Protein
PROTEIN SYNTHESIS
TRANSLATION: from mRNA to Protein
Amino acids are joined by peptide bonds
Chain of amino acids is formed until ribosome reaches a stop codon on the mRNA strand
When the amino acid chain is released from ribosome and assumes its 3-D shape, it becomes a protein!

17. Summary of Protein Synthesis
DNA in nucleus has instructions
Message from DNA goes to ribosome
Proteins are assembled on the ribosome according to the directions from the DNA
Transcription = taking message from nucleus to ribosome
Translation = using message directions to assemble proteins

18. Now watch and think – don’t write

30. TRANSLATION: from mRNA to Protein
PROTEIN SYNTHESIS
TRANSLATION: from mRNA to Protein
About those amino acids:
Which amino acid goes with which mRNA codon?
Example:
U-G-U
SEE CODON CHART
Now you try it…

36. TRANSLATION: from mRNA to Protein
PROTEIN SYNTHESIS
TRANSLATION: from mRNA to Protein
Now you try it
CODONS (p. 292)
mRNA amino acid
UCC
GCG
GGA
CUU
serine
alanine
glycine
leucine

38. Gene Regulation All cells of an organism have the same DNA.
What type of cell develops depends on which genes get turned on or off.
This is why a multicellular organism is able to differentiate into many types of cells. For example: skin cells, muscle cells, bone cells.

39. Gene Regulation
Cells respond to their environment by producing different types and amounts of protein.
Examples:
1. You get cut and your skin cells need to make proteins to repair your skin.
2. Cancer may result when your cells make too many cells (protein).
3. Diabetes may result if your pancreatic cells don’t make enough insulin (protein).