1. Diving into the gene pool: Chromosomes, genes and DNA
DNA is the stuff that genes are made of
DNA contains 4 letters: A, T, G, C
All genes are made of DNA, but not all DNA is in genes!

2. Diving into the gene pool: Chromosomes, genes and DNA
The entire DNA content of an organism is the genome.
The DNA is partitioned and packaged into structures called chromosomes. Humans have 46 chromosomes (23 pairs).

3. Diving into the gene pool: Chromosomes, genes and DNA
gene A
gene C
gene B
Genes are information carriers! They encode the instructions to make a protein. Proteins carry out the actual work of the cells.

4. Diving into the gene pool: From Genes to Proteins
DNA contains four letters: A T G C
Within a gene, these four letters are grouped into three letter “words”. Each word codes for an amino acid (the units that make up proteins). The combination of three letter words codes for the sequence of a protein.
DNA
ATG - CAT - AAA
Methionine - Histidine - Lysine
Protein

5. Diving into the gene pool: The Central Dogma
DNA
RNA
Protein
Why a middle man?

6. Diving into the gene pool: The Central Dogma
gene A
DNA
RNA
Protein
* In every cell
* Only turned “on”
where needed!
* Protein is made in the
cells where it functions –
not everywhere!

7. The Genome: What all is in there?
6 billion ‘letters’:
2-5 % protein coding genes
25% non protein coding genes
50%+ repeated sequences
Protein coding genes
Human: ,000-25,000
Mouse: ,000
Fly: ,000
Yeast: ,100
Mustard weed: 25,700

8. The Genome: What all is in there?
Nature 409:

9. The Genome: What all is in there?
Humans share…
….99% of chimp genes
….90% of mouse genes
….61% of fly genes
….43% of worm genes
….46% of yeast genes
* So what makes us different? *
more proteins/gene: ~22,000 genes but ~34,000 proteins
Expansion of gene families
The ways proteins interact and talk to one another

10. The Genome: What all is in there?
Regulatory sequences
gene A
general “on” signal
turn me off
in the brain
turn me on high
in the heart!
general “off” signal

11. The Genome: What all is in there?
Non-protein-coding RNA’s
some RNA’s are active and can function in the cell on their own
some RNA’s are incorporated into protein complexes to function
* The main functions of non-coding RNA’s are in protein production and regulation of gene expression

12. The Genome: What all is in there?
Repeat sequences
What is typically known as ‘junk DNA’
Why there? What does it do?
Repeated sequences shape the genome
Can increase the size of the genome
Often involved in chromosome translocations
Are sometimes responsible for human disease
Repeated sequences can be useful for understanding genome evolution, for tracking disease genes, and for forensic science (genetic fingerprinting)

13. The Genome: What all is in there?
Variation
Single Nucleotide Polymorphisms (SNPs)
~1 SNP per letters = 3 million differences between two genomes; we are still 99.9% the same!

14. The Genome: What all is in there?
Variation
Most SNP variation is outside genes
Within a gene, a SNP can have one of two effects
AAG
Lysine
AAA
Lysine
AAC
Asparagine

15. The Genome: What all is in there?
Variation: the ApoE example
ApoE gene contains 2 SNP’s = 3 alleles
Protein letter:
E2 Cysteine Cysteine
E3 Cysteine Arginine
E4 Arginine Arginine
E4/E4 genotype: greater chance for developing Alzeheimer’s
E2/E2 genotype: “protected” from getting Alzeheimer’s

16. Navagating the Genome
UCSC Genome browser: genome.ucsc.edu/cgi-bin/hgGateway
Ensemble Genome browser:
Online Mendelian Inheritance in Man:
(OMIM)