1. Protein Synthesis: Translation
Explain the basic processes of transcription and translation, and how they result in the expression of genes
EQ: Why are the sequence of nucleotides in DNA so important?

2. Protein Synthesis: building proteins (from our genes)
Last class we used
Transcription to turn
DNA RNA.
Today, we are going use
Translation to turn
RNA Protein.

3. The Players – Who is involved in protein synthesis?
DNA: Deoxyribose Nucleic Acid, Genetic Code to Life
mRNA: Copy of the message of the DNA, carries information in DNA out of the nucleus to make proteins.
rRNA: Located on the ribosome. Reads the mRNA instructions.
tRNA: Brings amino acids to mRNA in the ribosomes to create polypeptide chain.
Amino Acids: Monomers of proteins.
Polypeptide Chain: Polymer of proteins.

4. STEP 1: Transcription (DNA  RNA)
What happens?
mRNA is made (copied from DNA).
Where?
Occurs in the nucleus.
How?
The DNA strand is the template
RNA Bases are matched up
Why?
CG ; GC
To get the genetic information out of the nucleus
T A
A U (Instead of T)
mRNA leaves the nucleus

5. Practice with Transcription: Complete on LEFT
Let’s practice transcription! I’ll give you one strand of DNA, and you complete the complementary strand of RNA. (Remember, in RNA replace A with U).
DNA strand: ATT AGG CCG GAT TAG CCT ATT
RNA strand: UAA UCC k l

6. Practice with Transcription
Let’s practice transcription! I’ll give you one strand of DNA, and you complete the complementary strand of RNA. (Remember, in RNA replace A with U).
DNA strand: ATT AGG CCG GAT TAG CCT ATT
RNA strand:UAA UCC GGC CUA AUC GGA UAA

7. What does it mean to translate something?
DNA is a Common Language:
Almost all organisms share the same genetic code

8. Translation (Translating the RNA  Proteins)
What?
Turns mRNA into Protein.
Where?
Occurs in the ribosome in the cytoplasm of the cell.
How?
mRNA is read (decoded) in groups of 3 nucleotides called codons.
Codons are used to translate the message in mRNA to amino acids.
Amino acids bond together to make protein

9. Who is involved in translation?
Messenger RNA (mRNA)  carries the message or instructions
ribosome (rRNA) reads the message
transfer RNA (tRNA) Transport/transfer the amino acid
The product  amino acid (polypeptide chain)
ribosome
mRNA U C A G aa
tRNA G U aa
tRNA U A C aa
tRNA G A
tRNA aa A G U

10. Codons – The Code of Life
mRNA has the instructions, the instructions are CODONS.
A Codon is…
3 Nucleotides (one codon)
1 codon = 1 Amino Acid
An amino acid can have more than 1 codon code for it
Ribosomes “read” the mRNA codons and the tRNA retrieves the appropriate amino acid.
Some codons are special…
Start Codon: Signals the start of translation… (AUG)
Stop Codon: Signals the end of translation… (UGA, UAA, UAG)

11. We can use a codon chart to decode RNA.
2nd Nucleotide
1st Nucleotide
3rd Nucleotide

12. Check for Understanding: AUG, GGU, AND CAA,
You Try:
I NEED VOLUNTEERS!
Start codon
AUG
methionine
Stop codons
UGA, UAA, UAG

13. Different look, same idea
Use this chart to
Decode the following:
ACC
- Tht
CUC
- Leu
GAA
- Glu
UGA
- Stop

14. Protein Synthesis: All together now!
TACGCACATTTACGTACGCGG
DNA
codon
AUGCGUGUAAAUGCAUGCGCC
mRNA
ribosome
AUGCGUGUAAAUGCAUGCGCC
mRNA ?
Met Arg Val Asn Ala Cys Ala
protein aa
How do we know which amino acid it codes for ?

15. The Genetic Code – universal!
DNA is a code for building proteins but cannot leave the nucleus so Transcribed to mRNA
mRNA is decode (translated) into amino acids in the ribosomes
3 Nucleotides = 1 Codon = 1 Amino Acid
Proteins are the physical expression of our genes (DNA)
They are responsible for the visible variety of life found on Earth.
Proteins synthesis is the SAME for all living organisms.
Strong evidence for a single origin in evolutionary theory.

16. How DNA makes proteins 4. Translation 2. Transcription 1. DNA 3. RNA

17. Practice with Protein Synthesis
Let’s practice transcription! I’ll give you one strand of DNA, and you complete the complementary strand of RNA. (Remember, in RNA replace A with U).
DNA strand: TAC GCA TTA TCG ATA ATC
mRNA strand:
Amnio Acid chain:
AUG CGU AAU AGC UAU UAG
Met - arg - asp - ser – tyr- stop

18. Protein Synthesis: Let’s bring it all together!
DNA Replication: (not part of P.S.)
DNA copies itself.
Transcription:
mRNA is made from DNA in the nucleus.
Translation:
mRNA (from the nucleus) goes to the ribosome in the cytoplasm.
rRNA reads the mRNA code (from the start codon)
tRNA transfers the correct amino acid until the stop codon is reached. The chain of amino acids builds a protein.

19. Translation Practice Let’s practice translation!
(Remember, 3 nucleotides=1 amino acid)
C- level 2 voice
H – ask three before me, then raise your hand
A – Complete the translation practice worksheet with your group (15 min)
M- Remain seated with your pod (butt on the stool)
P- complete your own copy of the practice sheet
Success

20. Translation Exit: 1. mRNA strand:
DNA template: TAC GGG AAG CTT GTC ATT
1. mRNA strand:
2. amino acid chain:
2. Use the terms to describe
protein synthesis: (underline each word)
Amino acid
Nucleus
Translation
Transcription
Ribosome
codon
DNA/RNA
Protein