1. Chapter 12 and 13
Nucleic Acids, Protein Synthesis and Mutations Central Dogma DNA RNA Protein

2. Identifying the substance of Genes
Influential Scientists:
Griffith - Experimented with mice and bacteria that cause pneumonia and demonstrated TRANSFORMATION.
- Concluded that some FACTOR (gene) was responsible for the change.
Avery - Followed up on Griffith’s experiment; wanted to know which molecule was important for transformation.
He then extracted the 4 macromolecules from these heat killed cells, all of which were considered to be possible candidates for the carriers of genetic information.
Treated each mixture with enzymes that destroyed the macromolecule and transformation still occurred.
He concluded that DNA is the source of genetic information.

3. Figure 12–2 Griffith’s Experiment
Section 12-1
Heat-killed, disease-causing bacteria (smooth colonies)
Harmless bacteria (rough colonies)
Control (no growth)
Harmless bacteria (rough colonies)
Heat-killed, disease-causing bacteria (smooth colonies)
Disease-causing bacteria (smooth colonies)
Dies of pneumonia
Dies of pneumonia
Lives
Lives
Live, disease-causing bacteria (smooth colonies)

4. DNA Influential Scientists continued: Hershey and Chase-
Studied viruses – non-living particles that can infect living cells.
Looked at bacteriophages – a virus that infects bacteria.
Supported the conclusion that genes were made of DNA. DNA is the source of genetic information
Bacteriophage with phosphorus-32 in DNA
Phage infects bacterium
Radioactivity inside bacterium
Bacteriophage with sulfur-35 in protein coat
Phage infects bacterium
No radioactivity inside bacterium

5. Where is DNA found? Inside the nucleus DNA is coiled into Chromosomes

6. Components of DNA Nucleotide (monomer) Deoxyribose sugar
Phosphate group
Nitrogen-containing base
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Purines
Pyrimidines

7. Components of DNA
The structure or shape of DNA = Double Helix = 2 strands
Watson and Crick (1953) – tried to assemble the structure.
Rosalind Franklin (1952) – used a technique known as x-ray diffraction to create a picture.
The x shape indicated DNA is twisted (helix) around two strands.

8. DNA with Nucleotides Components of DNA Complementary Base Pairing
A↔T, G ↔C (Chargaff’s rule)
Connected by covalent hydrogen bonds
DNA with
Nucleotides

9. DNA Replication (duplication)
Takes place in the nucleus (during the S phase)
Result: 2 exact copies original DNA
DNA Polymerase
Helicase
Replication fork

10. DNA Replication (duplication)
1. Helicase unzips the double helix by breaking the hydrogen bonds forming a replication fork.
2. DNA polymerase adds the complimentary base pairs to each separated strand.
DNA Polymerase also “proofreads” each new strand.
Helicase
DNA Polymerase
Replication fork

11. DNA Replication, Accuracy & Repair
Original: A-T-T-C-C-G
Complement: TAAGGC
Original: GCTAAG
Complement:
Original: CTACCA
Original
Strand A: GACCTA
Strand B:
DNA polymerase proofreads & repairs1error/1Billion

12. Components of RNA Nucleotide Ribose Sugar Phosphate Group
Nitrogen Base
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U): not T
Single Strand
3 Types:
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)

13. How to make RNA Step 1 = Transcription: DNA RNA Takes place in the nucleus
DNA unwinds.
RNA Polymerase binds to DNA promoter site (begin gene)
3. Add complementary RNA nucleotides (U↔A)
Gene Begins
RNA Polymerase

14. Transcription Continued
4. DNA termination sequence signals gene end
5. RNA Polymerase releases DNA & RNA
RNA Polymerase
RNA Strand
DNA Rewinds

15. Transcription DNA makes RNA

16. 3 Types of RNA 1. 3.
Carries instructions from DNA to assemble amino acids into protein.
Carries the amino acids to the mRNA at the ribosome. 2.
The site where proteins get assembled from mRNA.

17. How to make Protein = Translation
Involves the decoding of mRNA and assembling a protein
Proteins = polymers = macromolecule
Monomer of protein = amino acid
Polypeptides = sequence of amino acids
Genetic code is read 3 letters at a time.
Codon: every 3 base pairs in mRNA = an amino acid
START Codon: starts translation- 1 codon only  AUG
STOP Codon: stops translation- 3 codons  UAA, UAG, UGA
Universal Codon -Amino Acid Code: p. 367

18. mRNA Codon & Codon Chart
AUG =
Methionine or
start codon
AAC = _________
Amino Acids

20. How to make Protein = Translation
tRNA
In cytosol
Binds specific amino acid to
mRNA
Anticodon:
complement to mRNA
codons

21. Translation: mRNA Protein
mRNA leaves nucleus
Ribosome attaches to mRNA
start codon
mRNA codon pairs with tRNA
anticodon delivering amino acid.
Peptide bond forms between
amino acids

22. Translation: mRNA Protein
mRNA stop codon signals
end of translation. The ribosome
releases the newly formed
polypeptide.
mRNA released &
polypeptide complete

23. Translation Diagram Polypeptide Chain Peptide Bond Nucleus Amino Acid
tRNA
Anticodon
Codon
mRNA
Ribosome

24. Overview DNA RNA Protein
Transcription
Translation

25. Mutations 2 categories of mutations
Mutations – are heritable changes in genetic info.
Occurs in only 2 types of cells
Sex-cell (germ-cell) mutations: gametes affect offspring
Somatic mutations: body cells  affect individual
2 categories of mutations
Gene mutations  produce change in a single gene
Chromosomal mutations  produce change in a whole chromosome.

26. Gene Mutations A.K.A. Point Mutations (3 types)
Substitution 1 nitrogen base gets substituted by another nitrogen base; this results in a new codon
Sickle Cell Anemia: substitute A for T

27. Gene Mutations (con’t)
Deletion
Nucleotide deletions & insertions
One base is inserted or removed from
the sequence.
- Causes Frame-shift mutations
Changes amino acid sequence
Insertion
Deletion

28. Chromosomal Mutations (5 types)
Deletion: lose portion 
Duplication: gain extra portion
Inversion: segment reverses
Translocation: transfer segment to non-homologous
Nondisjunction: gamete gets extra or less chromosome (Down Syndrome- Trisomy 21)

29. Chromosome Mutations Diagrams

30. Genetic Traits & Disorders
Disorders due to nondisjunction
Nondisjunction: gametes have 1 more or less chromosome (pairs don’t segregate)
Monosomy: 45 chromosomes
Turner’s syndrome: XO
Trisomy: 47 chromosomes
Down Syndrome: trisomy-21
Kleinfelter’s syndrome: XXY
Patau syndrome: trisomy-13
Edward’s syndrome: trisomy-18