2. Central Dogma of Genetics
Protein Synthesis
The process of reading the instructions in the DNA to make a protein.
Central Dogma of Genetics
DNA = instructions and is in the nucleus and can’t leave
But proteins are made in ribosomes
So protein synthesis takes 2 steps:
transcription
translation
DNA
RNA
protein

3. Remember Proteins??
Proteins are the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes such as:
Function as catalysts
Transport and store other molecules such as oxygen
Provide mechanical support and immune protection
Generate movement
Transmit nerve impulses
Control growth and differentiation.
#proteinsmatter

4. Three Essential Types of RNA
mRNA (messenger): copies instructions in DNA and carries these to the ribosomes in the cytoplasm
tRNA (transfer): carries amino acids to the ribosome and mRNA
rRNA (ribosomal): composes the ribosome

5. TRANSCRIPTION Purpose: Carry the code/instructions out of the nucleus
(Remember: DNA never leaves the nucleus, and proteins are made in the cytoplasm by ribosomes.)
Location: Nucleus
Starts with: DNA
Ends with: mRNA

6. (Remember: RNA has uracil instead of thymine, so A binds with U)
TRANSCRIPTION
Process:
RNA Polymerase binds to the DNA promoter where transcription is to begin and unzips the gene that needs to be copied. (looks for “TATA box” as a signal)
RNA Polymerase uses complementary base-pairing rules to match RNA nucleotides with the exposed DNA nucleotides
(Remember: RNA has uracil instead of thymine, so A binds with U)
Release the completed mRNA molecule
DNA zips back up and the mRNA leave the nucleus and enters the cytoplasm

7. Transcription: DNA is copied into a complementary strand of mRNA RNA is made in the 5’-3’ direction The DNA template read in the 3’-5’ direction 3’ 5’ 3’ 5’ 5’ 3’ 5’ 3’ 3’ 5’
DNA
mRNA
DNA
mRNA
DNA

8. Transcription – Try it! 3’ TACGCTAGTACGATT 5’ 5’ AUGCGAUCAUGCUAA 3’
DNA sequence (template):
3’ TACGCTAGTACGATT 5’
mRNA sequence:
5’ AUGCGAUCAUGCUAA 3’

9. Translation Vocabulary
Genetic Code: code of instructions for how to make proteins
Codon: a set of 3 nucleotides on the mRNA
mRNA
(messenger)
Amino acid –monomer (building block) for making proteins, held together by peptide bonds
Anticodon: “complementary” 3 nucleotides on tRNA
tRNA
(transfer)

10. TRANSLATION
Purpose: Read/follow the instructions carried on the mRNA to make a protein Location: Cytoplasm / Ribosome Starts with: mRNA Ends with: Protein

11. TRANSLATION
Process:
mRNA attaches to the small subunit of the ribosome
Ribosome reads the mRNA codons (3 mRNA nucleotides – like a triplet) ALWAYS in the 5’ to 3’ direction; starting at codon AUG.
tRNA (transfer RNA) molecules act like taxis to pick up and drop off the amino acids that match with the current codon being read off the mRNA.
tRNA’s continue to drop off amino acids, and the ribosome binds the amino acids together with peptide bonds
When the “stop codon” is reached, the ribosome releases the completed protein.

12. Translation: interpreting the RNA message into a protein.

13. The Genetic Code Resources I love:
Translation Animation:
Protein Synthesis Interactive:
Translation Animation:

14. Transcription and Translation: Try it!
DNA sequence (template):
3’ TACGCTAGTACGATT 5’
mRNA sequence:
5’ AUGCGAUCAUGCUAA 3’
Codons:
AUG CGA UCA UGC UAA
Amino Acids:
Met – Arg – Ser – Cys – stop