1. Protein Synthesis

2. Where is DNA found. What organelle makes proteins
Where is DNA found? What organelle makes proteins? Where are these organelles found? How does the information from DNA get to those organelles?

3. Protein Synthesis Overview
The information in DNA is used to make proteins. These proteins are used for a variety of purposes within the body. (do you remember why our body needs protein?)

4. However there is a problem. The DNA never leaves the nucleus
However there is a problem. The DNA never leaves the nucleus. But the ribosomes, (remember? they make proteins) are in the cytoplasm. How can the information get from the nucleus to the ribosomes in the cytoplasm?
The solution is that the cell makes a temporary copy of the DNA. The temporary copy is called RNA.

5. RNA RNA stands for ribonucleic acid
Found in both the nucleus and cytoplasm
Role: create a temporary copy of the instructions in DNA to send to the ribosome

6. RNA Structure Single stranded Like DNA, RNA is made of nucleotides
RNA nucleotides consist of:
1. Phosphate (acid)
2. Ribose (sugar)
3. Nitrogenous base

7. Nitrogen Bases 1. Adenine (A) 2. Uracil (U) – replaces thymine
3. Cytosine (C)
4. Guanine (G)

8. 3 Types of RNA
1. mRNA rRNA tRNA

9. Messenger RNA
(mRNA)
Acts as a messenger, carries a copy of the directions from the DNA in the nucleus to the ribosome in the cytoplasm

10. 2. Ribosomal RNA (rRNA)
Part of the ribosome
The ribosome is made up of proteins plus rRNA.

11. 3. Transfer RNA (tRNA) Remember:
Ribosomes make proteins, which are made of amino acids
tRNA brings those amino acids to the ribosome to be assembled into the correct order
Anti-codon

13. Draw DNA & RNA with their 4 bases in your notebook.

14. DNA and RNA
Similarities
Differences
Differences

15. The Central Dogma of Biology

16. 2 Steps: 1. Transcription 2. Translation Protein Synthesis
Stated Clearly Video
2 Steps:
1. Transcription
2. Translation

18. Step 1: Transcription
Transcription is the first step in protein synthesis.
Purpose: to make RNA, a copy of the information in DNA.
Location: in the nucleus.
To get started you need:
DNA
Free RNA nucleotides
RNA polymerase

20. Step 1: Initiation
RNA polymerase attaches to a promoter region of DNA
Promoter= specific sequence of DNA

21. Step 2: Elongation
RNA polymerase opens the DNA helix. It makes a little bubble. One strand will act as a template.
RNA polymerase moves down the DNA molecule attaching complementary RNA nucleotides as it goes.

22. Step 2: Elongation
Everything is the same as DNA replication except:
The DNA A pairs with RNA U

23. Match the DNA bases to the RNA basesG C
RNA

24. Step 3: Termination
Transcription stops when RNA polymerase reaches the terminator region of DNA.
Terminator signals
end of the gene.

25. RNA polymerase then detaches from the DNA
Step 3: Termination
RNA polymerase then detaches from the DNA
mRNA sent out of nucleus to cytoplasm after mRNA editing
Stated Clearly Video
Transcription Video
Animation

26. Summarize Transcription in your notebooks (bullet points)
Check your summary with a partner when finished.

28. mRNA Editing
Occurs directly after Transcription
Aka RNA splicing- essentially cutting and pasting of the mRNA
DNA & RNA contain portions called introns and exons

29. mRNA Editing
EXONS: pieces of DNA that are expressed- used to make proteins these are kept in mRNA
INTRONS: Not used to make proteins: Removed from mRNA

30. mRNA Editing
Finally:
A cap and a tail are added to the ends of the mRNA
Purpose:
Facilitates export out of nucleus
Protects from attack by enzymes
Helps ribosomes bind to it

31. Answer these questions in your notebook:
What are introns and exons?
Introns are pieces of DNA that do not code for proteins. Exons code for proteins
Are introns or exons important for protein synthesis?
Exons are necessary for protein synthesis- exons give us instructions to make proteins
Why do we edit the mRNA after copying DNA?
We edit out the introns because we only want the parts of the DNA that tell us how to make proteins. For protein synthesis, the introns are useless.

33. Step 2: Translation Location: In ribosomes in the cytoplasm
Purpose: To make proteins
How It Works:
The mRNA (copy of the DNA info) created in the nucleus moves to the ribosome in the cytoplasm
Ribosome reads the mRNA which tells the ribosome which amino acids to put together to make a protein

34. How do we read mRNA?:
mRNA contains codons- every 3 bases on mRNA = 1 codon
These codons code for (give instructions for) a certain amino acid
There are multiple codons for 1 amino acid
tRNA reads these codons and carries the necessary amino acid to the ribosome

35. Translation- Step 1. Initiation
2 ribosomal subunits attach to the mRNA
There is a START codon on mRNA which tells the ribosome to start bringing amino acids to it.

36. Translation Mechanism
MET
This process continues until a stop codon is reached, at which point the mRNA strand, tRNA units, and rRNA subunits all are released.
MET
ISO
PRO A U G C
tRNA
U A U
tRNA
U A C
tRNA
U A C
tRNA
U A U
tRNA
G G G
Start Codon (Methionine)
Large Ribosomal Subunit (rRNA)
E Site
A Site
P Site
mRNA A U G C
Small Ribosomal Subunit (rRNA)

37. Step 2: Elongation mRNA= has codon
A. Codon recognition occurs
mRNA= has codon
tRNa = has anti-codon which matches the mRNA codon
tRNA with anti-codon that matches the mRNA START codon attaches to ribosome, bringing an amino acid with it
Another tRNA attaches to ribosome

38. Step 2: Elongation B. Peptide Bond Formation
Ribosome forms a peptide bond between the amino acids from tRNA to start a chain
Old tRNA leaves ribosome while new one attaches- continues until STOP codon reached

41. Step 3: Termination STOP codon is reached
STOP codon tells tRNA to stop binding to ribosome
Ribosome pulls away from mRNA
Translation complete- ending with a complete protein
Translation Animation

42. Post-Translation . . .
The new protein is released. The string of amino acids fold- up into the shape of the protein. Protein sent to Golgi for packaging and shipping

43. Summarize Translation in your notebooks (bullet points)
Check your summary with a partner when finished.

48. Practice Creating Proteins
Using the chart on your guide, find the amino acid sequence created from the following strands of DNA:

49. Genetic Mutations Mutation = Changes in the DNA sequence
Mutagenesis – the production of mutations
Mutagen – something that causes mutations
A physical or chemical agent such as x-rays, high-energy radiation, chemicals
Spontaneous – occur during replication or other similar processes
Genetic mutations

50. Gene Mutation

51. Two types of Mutations Point mutation (results from substitutions)
Gene mutations – within a single gene
Point mutation (results from substitutions)
Ex: TAC changes to AAC
Genetic disorder ex: Sickle cell anemia, Cystic Fibrosis
Silent mutation – diff codon, but same amino acid
Frameshift mutation (results from insertions/deletions)
Ex: insert a T after first T so TAC – GCC changes to TTA – CGC - C