1. MOLECULAR GENETICS

2. what is DNA?
23 and me

3. History (1): The transforming principle

4. History (2): Hershey & Chase Experiment

5. Central Dogma of Molecular Biology
DNA  RNA  protein

7. DNA contains all the genetic information about an organism.
Regions on DNA that code for specific attributes are called genes.
3) In order for the information within a gene to be useful, it has to be translated into proteins.

8. The end proteins determine individual traits!

9. What makes good genetic material?
Stable source of information
Ability to replicate accurately
Capable of change

10. Watson and Crick “Discovered” the structure of DNA in 1953
Used the knowledge of many other scientists to determine the structure
Awarded the Nobel prize in 1962 for DNA’s structure*

11. Why care?
- genes are segments of DNA responsible for the production of a functional protein.
- genes are responsible for your traits! Ex. widow’s peak, skin tone, etc
Environment can be a factor in traits as well*
- Every person has two copies of each gene, one inherited from each parent.

12. Genes
Genes are units of heredity that are passed on from parent to offspring.
Genes give specific instructions for one characteristic.
One gene = one polypeptide (not really…)

13. Genome
*the complete genetic makeup of an organism, its total DNA sequence*

14. C value = total amount of DNA in the haploid (1N) genome
Varies widely from species to species and shows no relationship to structural or organizational complexity.
Examples C value (bp)
 ,502
T ,900
HIV ,750
E. Coli ,639,221
Lilium formosanum 36,000,000,000
Zea mays 5,000,000,000
Amoeba proteus 290,000,000,000
Drosophila melanogaster ,000,000
Mus musculus 3,454,200,000
Canis familiaris 3,355,500,000
Equus caballus 3,311,000,000
Homo sapiens 3,400,000,000

15. Problem:
Measured linearly, the Escherichia coli genome (4.6 Mb) would be 1,000
times longer than the E. coli cell.
The human genome (3.4 Gb) would be 2.3 m long if stretched linearly.
*this stuff needs to get organized!

16. Organization of DNA 1.a) Supercoiling
DNA double helix is twisted in space about its own axis, a process is controlled by topoisomerases
occurs in circular and linear DNA molecules
b) Looped domains

17. Different levels of organization
1. Prokaryotic chromosomes
- most contain one double-stranded circular DNA chromosome
- others consist of one or more chromosomes
and are either circular or linear
- arranged in arranged in a dense clump (nucleoid)

18. 2. Viral chromosomes TMV T2 bacteriophage
single or double-stranded DNA or RNA
circular or linear
surrounded by proteins
TMV T bacteriophage

19. 3. Eukaryotic chromosomes
because we have A LOT of DNA in each cell it needs to be packaged in a specific way

20. Chromosomes are compact molecules of DNA
A human set of chromosomes contains 23 pairs
23rd pair are your sex chromosomes
Karyotype

21. Where are your genes?

22. Eukaryotic chromosome structure
Chromatin:
- non-condensed complex of DNA and chromosomal proteins, about twice as much protein as DNA
Two major types of proteins
Histones
abundant, basic proteins with a positive charge that bind to DNA
evolutionarily conserved
2. Non-histones
- all the other proteins associated with DNA
- differ markedly in type and structure

23. Packing of DNA into chromosomes
Level 1
Winding of DNA around histones to create a nucleosome structure.
Level 2
Nucleosomes connected by strands of linker DNA like beads on a string.
Level 3
Packaging of nucleosomes into 30-nm chromatin fiber.
Level 4
Formation of looped domains.