1. What is it? When is it done? What is copied?
DNA Replication
What is it?
When is it done?
What is copied?

2. Two New, Identical DNA Strands Result from Replication
Replication is called semiconservative because each new double helix is composed of an old (parental) strand and a new (daughter) strand.

3. PROTEIN SYNTHESIS

4. Protein Synthesis
After replication and cell division, each new cell has its own DNA
Now, how do those cells use that DNA to make proteins?
How do you go from DNA (nucleic acid) to protein (amino acid)?

5. Overview of Protein Synthesis
Copy (mRNA) is made of gene
mRNA sent out of nucleus
Ribosomes use mRNA as instructions to make a protein

6. Protein Synthesis Two phases: DNA Transcription mRNA Translation

7. Transcription

8. Transcription In nucleus DNA the template for mRNA
RNA polymerase makes the mRNA

9. Only one DNA strand is used Just a portion of the DNA is copied (one gene) copy is called mRNA

10. DNA RNA RNA Differs from DNA T (thymine) U (uracil) Deoxyribose sugar
Double stranded
Single stranded
T (thymine)
U (uracil)

11. Question:
What would be the complementary RNA strand for the following DNA sequence?
DNA 5’-GCGTATG-3’

12. Answer:
DNA 5’-GCGTATG-3’
RNA 3’-CGCAUAC-5’

13. Translation
mRNA protein

14. Translation
mRNA
ribosome
Ribosome reads the mRNA and makes protein

15. mRNA leaves nucleus
ribosome attaches to mRNA
ribosome reads the bases in groups of 3 (codon)
AUG
CUG
codon

16. The ribosome uses the code to make the protein How
The ribosome uses the code to make the protein How? How do you go from nucleic acid to amino acid?

17. tRNA Carries amino acids to ribosomeU A C
Amino acid
Carries amino acids to ribosome
Has anticodons that are complementary to mRNA codons

18. A A
UAC
AUG
CUG

21. Genetic Code DNA contains a triplet code
Every three bases on DNA stands for ONE amino acid
Codon: Each group of 3 bases on mRNA
The fact that the genetic code is about universal in living things suggests that the code dates back to the first organisms on earth and that all living things are related.

22. r

23. Gene Mutations Chromosome Mutations

24. What happens when there is a mistake during replication?
What could go wrong when the DNA is being replicated?

25. Gene Mutations Point Mutations A. Substitution Frame shift Mutations
Insertion
Deletion

26. Point Mutations – substitution
One WRONG BASE is used
Original The fat cat ate the wee rat.
Mutation The fat hat ate the wee rat

27. Examples of Point Mutations
Sickle Cell Anemia

28. Examples of Point Mutations
Tay Sachs Hemophilia B

29. Frame Shift Mutations A Insertion AAT AGG CAG GTT
Deletion AAT AGG CAG GTT

30. Frame Shift Mutations A Insertion AAT AGG CAG GTT
becomes AAT AAG GCA GGT …
Deletion AAT AGG CAG GTT
becomes AAA GGC AGG …

31. Frame Shift Original The fat cat ate the wee rat.
Insertion The fat caa tet hew eer at.

32. Example of Frame Shift Mutation:
Huntington’s Disease

33. Chromosome Mutations 1. Inversions 2. Duplications 3. Deletions
4. Translocations

35. Incorrect Chromosome Number – from nondisjunction during meiosis
Trisomy 21 causes Down’s Syndrome