Define genome
-the complete set of genetic material encoded in a cell or virus
-does NOT include DNA from organelles (ie. mitochondria)
-Human genome =23 chromosomes
22 autosomes, 2 sex
Intronic and intergenetic regions
-can contain regulatory sequences (ie. enhancers)
The gene unit
- regulatory regions (UTRs, promoters)
- Introns
- Exons
functional DNA
- improves an organisms fitness
- the functional components are highly conserved (sequence-wise)
- contains coding and non-coding DNA
non-functional DNA
-has no known biological contributions
coding DNA
-codes for a specific protein
non-coding DNA
does NOT code for a protein
What percentage of the genome codes for proteins?
1.5%
When considering all components of the gene unit, protein coding genes make up approximately what percentage of the human genome?
approx 33% (1/3)
Homolog
- two genes with a demonstrable sequence similarity
- implies evolutionary relationship
- independent of functional relationship
Orthologs
- 2 genes in a different species with a clear sequence and functional relationship
- derived from the gene in a common ancestor
Paralogs
- related genes within the same species
- ie. gene families
Chromosome structure
P-arm -shorter arm of the chromosome Q-arm -longer arm of the chromosome Centromere
Single nucleotide polymorphism (SNPs)
-genomic base pair change that helps distinguish species from each other or one subset of individuals in a population
Large genomic rearrangements
-large alterations within the DNA sequence in chromosomes
Inversions:
-inversion of a large segment of DNA
Fusions:
-rearrangement of chromosomal DNA by deletion, duplication, insertion or transposition
Human vs. Chimp genome
- SNPs=1%
- approx 5 million short insertions/deletions a few BP each
- approx 40-45million BP difference total, approx 4% total difference between human and chimp genomes
Outgroups
- compare SNPs for two different species (ie. Human, chimp)
- determine outgroup that diverged prior to the two species common ancestor (ie. orangutan) by comparing the SNPs from the three species
Components that make up a genome
- coding sequences for RNA and protein mlc
- signals for chromatin condensation/chromatin remodelling
- Signals for initiation of replication and chromosomal integrity
- Control signals for on/off, levels of expression
- Start and stop sites for transcription
- Processing signals for primary transcripts
- Control signals for dynamic access at right time and place
- Identifiers for coding sequences that must be coordinately or sequentially expressed
