1. Protein Synthesis (Gene Expression) Notes
DNA RNA Protein Trait
Protein Synthesis (Gene Expression) Notes
Proteins (Review)
Proteins make up all living materials

2. Proteins are composed of amino acids – there are 20 different amino acids
Different proteins are made by combining these 20 amino acids in different combinations

3. Proteins are manufactured (made) by the ribosomes

4. Function of proteins: Help fight disease Build new body tissue
Enzymes used for digestion and other chemical reactions are proteins
(Enzymes speed up the rate of a reaction)
Component of all cell membranes
Answer the first 4 questions on your protein synthesis flow chart.

5. Genes Genes are the instruction manuals for our bodies.
They are the directions for building all the proteins that make our body function.
Genes are made of DNA.

6. Gene Expression
Not all genes are active or expressed at the same time.
Why: Because the cell would produce molecules it did NOT need – waste of energy and raw materials

7. Gene expression (protein synthesis) is when the
Gene expression (protein synthesis) is when the product of a gene, or a specific protein is being produced by a cell.
some genes are – rarely expressed – adrenaline
some genes are – constantly expressed – hair growth, blood pressure
some genes are expressed sometimes and turned off others – estrogen.

8. Making a Protein—Transcription
First Step: Copying of genetic information from DNA to RNA called Transcription
Why? DNA has the genetic code for the protein that needs to be made, but proteins are made by the ribosomes—ribosomes are outside the nucleus in the cytoplasm.
DNA is too large to leave the nucleus (double stranded), but RNA can leave the nucleus (single stranded).

9. Nucleus

10. Part of DNA temporarily unzips and is used as a template to assemble complementary nucleotides into messenger RNA (mRNA).

11. Nucleus
mRNA
DNA
DNA A U A T U A G C C

12. mRNA then goes through the pores of the nucleus with the DNA code and attaches to the ribosome.

13. Nucleus
Original DNA
mRNA
Ribosome

14. Making a Protein—Translation
Second Step: Decoding of mRNA into a protein is called Translation.
Transfer RNA (tRNA) carries amino acids from the cytoplasm to the ribosome.

15. These amino acids come from the food we eat
These amino acids come from the food we eat. Proteins we eat are broken down into individual amino acids and then simply rearranged into new proteins according to the needs and directions of our DNA.

16. A series of three adjacent bases in an mRNA molecule codes for a specific amino acid—called a codon.
A triplet of nucleotides in tRNA that is complementary to the codon in mRNA—called an anticodon.
Each tRNA codes for a different amino acid.
Amino acid
Anticodon

17. mRNA carrying the DNA instructions and tRNA carrying amino acids meet in the ribosomes.

18. Amino acids are joined together to make a protein.
Polypeptide = Protein

19. CAC/CCA/UGG/UGA AUG/AAC/GAC/UAA
Use one of the codon charts on the next page to find the amino acid sequence coded for by the following mRNA strands.
CAC/CCA/UGG/UGA
___________/___________/___________/____________
AUG/AAC/GAC/UAA

20. ___________/___________/___________/____________ Histidine Proline
CAC/CCA/UGG/UGA
___________/___________/___________/____________
Histidine
Proline
Tryptophan
Stop
1st Base
2nd Base
3rd Base

21. AUG/AAC/GAC/UAA
___________/___________/___________/____________
Methionine
Asparagine
Aspartic Acid
Stop

22. Protein Synthesis

24. Movie about translation at bottom of webpage
Movie about translation at bottom of webpage. Click on hyperlink in picture above.

25. VIDEO – yea…its pretty AWESOME!

26. MUTATIONS
A sequence of a gene can be changed in several ways. These changes or mutations can cause no effect to the individual (They could code for the exact same protein even with the new base) OR they can cause large effects to the individual .

27. Point Mutation  SUBSTITUTION
3 examples of gene mutations that happen at a certain point (called point mutations):
1. __substitution___ a mutation in which 1 nucleotide
is exchanged for another.

28. Mutation -- INSERTION
2. __insertion___ a mutation in which 1 or more _extra nucleotides is added to DNA. G C

29. 3. __deletion___ a mutation in which 1 nucleotide
Mutation - Deletion
3. __deletion___ a mutation in which 1 nucleotide
is taken out or deleted. G

30. Gene Mutation Example
Table 1: Single-Base Mutation Associated with Sickle-Cell Anemia
Sequence for Wild-Type Hemoglobin
ATG
GTG
CAC
CTG
ACT
CCT
GAG
AAG
TCT
GCC
GTT
Start
Val
His
Leu
Thr
Pro
Glu
Lys
Ser
Ala
Sequence for Mutant (Sickle-Cell) Hemoglobin