1. DNA Unit

2. Structure of DNA
- shape is a double helix
- a long polymer made of smaller units (monomers) called nucleotides

3. Structure of DNA (cont)
- 4 different types of nucleotides
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)

4. Structure of DNA (cont)
- held together by hydrogen bonds
- pairing rules:
A binds with T
G binds with C

5. Discovery of DNA
model of shape proposed by Watson and Crick
Discovery made 1953
- won Nobel Prize in 1962

6. Discovery of DNA (cont)
- Rosalind Franklin produced X ray photographs of DNA
- helped Watson and Crick develop their model
- Did NOT win Nobel Prize for her work

7. = the process of copying DNA - happens in the nucleus
Replication
= the process of copying DNA
- happens in the nucleus
- DNA polymerases = enzymes that bond new nucleotides together
TEM 500,000x

8. Replication

9. Replication

10. Replication

11. Replication (cont)
- result is two identical strands of DNA
- process has a proofreading system to correct errors

12. Replication (cont) - example: ATAGCTAGCTTC TATCGATCGAAG ATAGCTAGCTTC

13. Transcription
= process of copying information from DNA to mRNA (messenger RNA)
- happens in the nucleus
- RNA polymerases = enzymes that bond nucleotides to a mRNA strand

14. Transcription (cont) - one side of the DNA (the template) is used
- new rule: uracil (U) replaces thymine (T)
- U binds with A (but only in RNA)

15. Transcription

16. Transcription

17. Transcription

18. Transcription (cont) Transcription (mRNA) ATAGCTAGCTTC TATCGATCGAAG
- example:
(template)
Transcription
(mRNA)
ATAGCTAGCTTC
TATCGATCGAAG
ATAGCTAGCTTC
UAUCGAUCGAAG

19. = the process that converts info in mRNA into proteins
Translation
= the process that converts info in mRNA into proteins
- done by ribosomes in the cytoplasm
- codon = 3 nucleotides together
- each represents an amino acid
Codon
Codon

20. Translation (cont)
- example:
(mRNA)
Translation
UAUCGAUCGAAG

21. Translation (cont) UAU CGA UCG AAG Amino Acid Sequence = a protein
Chart
- example (cont):
mRNA strand broken into codons
Amino Acid Sequence = a protein
UAU CGA UCG AAG

23. Translation (cont) Amino Acid Sequence = a protein UAU CGA UCG AAG
Chart
- example (cont):
mRNA strand broken into codons
Amino Acid Sequence = a protein
UAU CGA UCG AAG
Tyrosine
Serine
Arginine
Lysine

24. Central Dogma
= the flow of information from DNA to RNA to proteins
- involves the three main processes: replication
transcription
translation

25. Mutations
= a change in an organism’s DNA
- they can be neutral (do nothing), harmful, or beneficial
- a mutation may or may not effect the organism
- depends on number of genes involved and location of mutation

26. Mutation Examples - Neutral
mRNA sequence is AAG
Codes for Amino Acid
mRNA sequence changes to AAA
Mutation did not affect the end outcome of what amino acid is produced
Lysine
Lysine
Chart

27. Mutation Examples - Beneficial
Coronary Heart Disease
Mutation
Normal
Blockage of the Coronary Artery supplying blood to the heart
Mutation helps protect people from blocked arteries

28. Mutations (cont)
- mutations in body cells (SOMATIC) affect only the organism itself and are not passed to offspring

29. Mutations (cont)
- mutations in sex cells- GAMETES (egg and sperm) may be passed to offspring
- most of the time this is bad, but not always
- another source of genetic variation in organisms

30. - Mutagens = agents in the environment that can cause a change in DNA
Mutations (cont)
- Mutagens = agents in the environment that can cause a change in DNA
- ex: UV Light, industrial chemicals
Rachel Carson – one of the first ecologist to warn against the widespread use of pesticides and other potential mutagens and toxins in her book Silent Spring in Her book helped launch the environmental movement.