PowerPoint for BI 520-01 Spring 2013

1. Lecture 1
What is it to be alive?
©

4. Lecture 1

8. Lecture 1

9. Chapter 1

10. Lecture 1

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12. Lecture 1
Prokaryotic Gene
Promoter Protein Coding Sequence Terminator
Intron ~20 bp
Eukaryotic Gene
Exon 1 Exon 2 Exon 3
Promoter
Intron ~2kb Intron>5kb Intron~5kb

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15. So, who’s wrong?
Both!

16. Lecture 1
One of the most profound technological
accomplishments in human history is the
sequencing of the human genome…

17. Lecture 1
One of the major differences between prokaryotes and
eukaryotes in the size/complexity of their genomes.

18. Lecture 1

19. Lecture 1

21. Mutation – a change in the nucleotide sequence of the genetic
material of an organism – is the underlying force of evolution.
•Mistakes during replication
•Chemical Changes in the nucleic acids
•UV – dimerization
•Spontaneous decomposition – base changes
•Chemical/physical changes at the chromosome level
•Radiation (X-ray/Gamma) – double-strand breaks
•Sexual reproduction (polyploidy)

22. Lecture 1
More than 200
gene families are
common to all life.
Most of these
“orthologous
genes” are
essential.

23. Lecture 1
But how do they do this when
most mutations tend to mess
things up more than they
improve them?

24. They must find a way to
break free from the
oppression of natural
selection

25. Lecture 1
Duplication events Retroviruses
Horizontal Gene Transfer - genes can be
transferred between organisms both in the
laboratory, and in nature.

26. hCYP3A Locus
Chromosome-7 ~80% Homology
40 Kb 4 Kb 5 Kb
P2 P1
3A43 3A4 3A7 3A5
43cDNA 4cDNA 7cDNA 5cDNA
All have roughly 90% homology in the first 1000 bp of their
promoters.
Finta & Zaphiropoulos, 2000 Gellner et al., 2001

27. Irreducible complexity

28. Lecture 1
Eukaryotes often have pseudogenes,
duplicated genes that have accrued
mutations that render them inactive, in
their genomes.
Mutated regulatory elements, frame
shifts, addition/loss of stop codons,
lost splice sites, deleterious mutations,
etc.

30. Lecture 1

31. Conoidea based on 12S Ribosomal RNA

32. Lecture 1
We make assumptions when we do this…
•Evolution is real - members of a group share a common
evolutionary history, and are "closely related," more so to
members of the same group than to other organisms.
•Bifurcation - new kinds of organisms may arise when existing
species or populations divide into exactly two groups.
•Organisms change over time – closely-related groups are
share synapomorphies, unique features not present in more
distant ancestors
And even more when we use gene sequences…
•Mutations are a “one-way” street
•We can assign a “value” for every base-pair mutated
•“horizontal gene transfer” has not occurred among the
orthologues.

33. Lecture 1
The identification and characterization of gene
orthologues helps us in ever expanding ways:
1. Enhanced discovery
• By finding regions that are highly conserved, primers can
be designed to discover orthologues from new species
2. Accelerated science
• We can compare gene sequences and hint at their
function, expression patterns, etc.
3. More powerful experiments
• We can plan methods to genetically engineer just about
anything
4. GAAATAACA and Pharmacogenomics
• We can peer into our own genomes and predict certain
diseases and the success of many treatments