1. DNA, RNA,
and Proteins
By Liz LaRosa

2. DNA and Protein Synthesis
DNA contains the genetic information to
make amino acids
Amino acids combine to make proteins
These proteins determine the physical traits
of an organism and control cellular functions.
Proteins do everything,
and DNA gets all the
credit!
Think of them as tiny minions
who do all the work

3. DNA and Protein Synthesis

4. DNA and Protein Synthesis
Codon: three bases code for a specific protein:
ex: AAA = Lysine
The codons code for 20 amino acids
Just like the alphabet has 26 letters to make all
the words we know, the 20 amino acids make
all the different proteins found in living
organisms
The codons are the template for protein synthesis,
which takes place on the ribosomes (rRNA) in the
cytoplasm

5. Name the Amino Acid: UAU CCG AGU Tyrosine GCA Proline Serine Alanine
DNA and Protein Synthesis – Codons and amino acids
Name the Amino Acid:
UAU
CCG
AGU
GCA
Tyrosine
Proline
Serine
Alanine

6. But… How does the information get from the DNA to the cytoplasm?
DNA and Protein Synthesis
But… How does the information get from the DNA to the cytoplasm?
mRNA

7. Messenger RNA (mRNA) carries the DNA message out
into the cytoplasm where protein synthesis takes place.

8. DNA and Protein Synthesis - Transcription
1) DNA unzips
2) mRNA (messenger ribonucleic acid) copies info from DNA using base pairings
RNA is different from DNA
Single stranded, not double stranded
Instead of deoxyribose, it has ribose
instead of Thymine, it uses Uracil
3) Carries the genetic code from the nucleus to the
ribosome in the cytoplasm

9. DNA and Protein Synthesis - Translation
rRNA (ribosomal RNA) attaches to mRNA and starts reading the codons
tRNA (transfer RNA) – carries amino acids and attaches them to the growing protein chain
When protein production is complete, the ribosome releases the protein chain

11. DNA and Protein Synthesis - Summary

12. DNA G A T T A C A C U A A U G U mRNA
DNA and Protein Synthesis
Practice making mRNA using the DNA template
DNA
G A T T A C A
C U A A U G U
mRNA

13. mRNA CUA AUG UGC DNA and Protein Synthesis
Amino acids are linked together in the same
order as the codons , creating a protein chain
Just like linking letters to make words, linking
amino acids makes proteins
mRNA
CUA AUG UGC
Leucine methionine
Amino Acid
Amino Acid
Amino Acid

14. Translation
Translation begins when a ribosome attaches to an mRNA molecule in the cytoplasm.
As the ribosome reads each codon of mRNA, it directs tRNA to bring the specified amino acid into the ribosome.
One at a time, the ribosome then attaches each amino acid to the growing chain.

15. Translation Each tRNA molecule carries just one kind of amino acid.
In addition, each tRNA molecule has three unpaired bases, collectively called the anticodon—which is complementary to one mRNA codon.
The tRNA molecule for methionine has the anticodon UAC, which pairs with the methionine codon, AUG.

16. Translation
The ribosome has a second binding site for a tRNA molecule for the next codon.
If that next codon is UUC, a tRNA molecule with an AAG anticodon brings the amino acid phenylalanine into the ribosome.

17. Translation
The ribosome helps form a peptide bond between the first and second amino acids—methionine and phenylalanine.
At the same time, the bond holding the first tRNA molecule to its amino acid is broken.

18. Translation
That tRNA then moves into a third binding site, from which it exits the ribosome.
The ribosome then moves to the third codon, where tRNA brings it the amino acid specified by the third codon.

19. Translation
The polypeptide chain continues to grow until the ribosome reaches a “stop” codon on the mRNA molecule.
When the ribosome reaches a stop codon, it releases both the newly formed polypeptide and the mRNA molecule, completing the process of translation.

22. Mutations are any changes that take place in DNA:
DNA and Mutations
Mutations are any changes that take place in DNA:
Can be spontaneous or caused by mutagens
ex: Chemicals, high temperatures, UV light,
radiation
Can change the genetic code, and be replicated
when forming new body cells.
In sex cells, can be passed on to offspring.
Mutations can be neutral, beneficial, or harmful
ex: Blue eyes – a mutation that occurred 6-10,000 years ago, can be traced back to one ancestor
what kind of mutation is that?

23. DNA and Mutations – Lets looks at different mutations
THE DOG BIT THE CAT

24. Substitution - Replace just one letter: THE DOG BIT THE CAR
DNA and Mutations - Substitution
THE DOG BIT THE CAT
Substitution - Replace just one letter:
THE DOG BIT THE CAR

25. Deletion: Delete just one letter (T): THE DOG BIT HEC AT
DNA and Mutations - Deletion
THE DOG BIT THE CAT
Deletion: Delete just one letter (T):
THE DOG BIT HEC AT

26. Insertion - Add just one letter (E): THE DOE GBI TTH ECA T
DNA and Mutations-Insertions
THE DOG BIT THE CAT
Insertion - Add just one letter (E):
THE DOE GBI TTH ECA T
Cells have “proof reading” proteins that constantly check the DNA and fix errors, so most are corrected