1. Protein Synthesis

2. The Process
In order to make proteins (which are used to express traits) a number of steps must be followed:
1) DNA is used as a blueprint to make RNA.
2) RNA then directs the making of proteins.

3. The Process 1) 2)

4. Things to Know Beforehand
i) DNA and RNA work together to create all of our proteins.
ii) DNA and RNA are not the same thing.
iii) There are 3 different types of RNA

5. DNA vs. RNA Deoxyribose Sugars Double Stranded Nucleus only
Bases: A, C, G, T
DNA
Ribose Sugars
Single Strand
Nucleus & Cytoplasm
Bases: A, C, G, U
mRNA, tRNA, rRNA

6. messenger (mRNA) R R R R

7. transfer (tRNA)

8. ribosomal (rRNA)
LARGE RIBOSOME
SMALL RIBOSOME

9. The Process in General
In order to use DNA to make proteins there are 2 stages that are needed:
Transcription – DNA is rewritten into RNA.
Translation – the 3 types of RNA work together to assemble amino acids into proteins.

10. A) DNA to RNA

11. B) 3 RNA’s make Proteins
tRNA
rRNA
mRNA

12. Terms to Know
Genetic Code – every single set of three nucleotides in DNA/RNA correspond to a particular amino acid.
Codon – a set of three nucleotides.
There are 64 possible combinations of three letter nucleotides (AAA, AAG, AAC, AAU, AGA, etc.) but only 20 amino acids.

13. A) DNA to RNA (Transcription)
Four Steps: (similar to DNA Replication)
RNA Polymerase binds to the “start” codon of DNA.
RNA Polymerase unwinds and separates the two strands of DNA*.
*This is just like what DNA Helicase did.

14. DNA to RNA (Transcription)
RNA Polymerase adds and links new nucleotides together and continues until a “stop” codon is reached**.
(Base pairing is C–G and A–U)
The newly created mRNA strand leaves the nucleus and the DNA rejoins back together.
**This is just like what DNA Polymerase did.

16. Animations Replication (DNA to DNA): Transcription (DNA to RNA):
Transcription (DNA to RNA):

17. Replication vs. Transcription
DNA Helicase & DNA Polymerase are used
DNA nucleotides linked
2 DNA molecules made
Both (2) DNA strands act as templates
Only RNA Polymerase is used
RNA nucleotides linked
1 RNA molecule made
Only 1 strand of DNA acts as a template

18. The Genetic Code Many different mRNA’s are made during transcription.
Each mRNA has instructions for a different type of protein.
The instructions are written in sets of three nucleotides called codons.

19. The Genetic Code Each codon stands for a specific amino acid.
When enough amino acids are connected together they form a protein.

20. Breaking the Code
In 1961, Marshall Nirumburg broke the code of the first codon, he saw that UUU made the amino acid phenylalanine.
Soon after the rest of the codons were deciphered as well.
Key Codons Include:
AUG = methionine = “start”
UGA, UAA, UAG = “stop”

21. Breaking the Code
Page 209

22. B) RNA to Protein (Translation)
Translation requires the use of different types of RNA:
a) messenger RNA (mRNA)
b) transfer RNA (tRNA)
c) ribosomal (rRNA)
Translation occurs in ribosomes, which are made of two parts called the large and small subunits.

24. RNA to Protein (Translation)
tRNA
rRNA
mRNA

25. RNA to Protein (Translation)

26. RNA to Protein (Translation)

27. RNA to Protein (Translation)
The Seven Steps:
The ribosome subunits, the mRNA and the tRNA all bind together at the “P-site.”
A second tRNA binds to the “A-site.”
The amino acids on the top of the tRNA’s form a peptide bond when close together.

28. B) RNA to Protein (Translation)
The tRNA at the “P-site” breaks away, but leaves its amino acid behind.
The tRNA at the “A-site” moves to the “P-site” and a new tRNA enters the “A-site.”
Steps 3-5 repeat.

29. B) RNA to Protein (Translation)
Translation ends when a “stop” codon is reached, then all parts break up.
* All of the amino acids that were joined stay together to become a protein.
** Proteins are used to express all genes.

30. Protein Synthesis

31. Mutations
Gene mutations result from changes in a single gene. Chromosomal mutations involve changes whole chromosomes.

32. Gene Mutation
Point Mutation – Affect one nucleotide thus occurring at a single point on the gene. Usually one nucleotide is substituted for another nucleotide.
Frameshift Mutation – Inserting an extra nucleotide or deleting a nucleotide causes the entire code to “shift”. More severe consequences

33. Gene Mutation

34. Chromosomal Mutations
Deletion – Part of a chromosome is deleted
Duplication – part of a chromosome is duplicated
Inversion – chromosome twists and inverts the code.
Translocation – Genetic information is traded between nonhomologous chromosomes.

35. Chromosomal Mutations

36. Any Questions?
“If your work is becoming uninteresting so are you. Work is an inanimate thing and can be made lively and interesting only by injecting yourself into it.”
--Dale Carnegie