Evolution and Azt Essays

Submitted By Jamelmell
Words: 629
Pages: 3

Evolution

The central theory of biology
Most influential on all aspect of biological research
“Nothing makes sense in biology except in the light of evolution” T. Dobzhanski (1900-1975)

Main Concepts

Natural Selection
Movement of Alleles in pops. And between generations
Tree thinking
Trade-offs

“Evolution in Five Stories”

HIV – an evolutionary case studies
The evolution of sex
The 'Dover trial’
What makes mammals mammals?
Human evolution

Peppered Moth

Genetics of Industrial Melanism
How are black and white phenotype inherited?
One gene/locus:
Wild-type  white;
Mutant  dark (dominant)
Similar: Human brown/blue eyes:
Wild-type  brown
Mutant  blue (recessive)

January 21, 2014

Are peppered moth/eye color typical examples for diversity – and selection acting on it?
Can you think of other traits with similar inheritance/diversity?
Skin color, Widows peak, Attached or unattached earlobes, chin
Or traits that differ in diversity, genetics?
Hair color, height
What kind of trait are you thinking of, in the context of selection?
Broad traits
Is the peppered moth a good example to teach/explain evolution?
Quantitative Genetics
Many loci  greater distribution
Heritability
The environment has a great impact
Response to Selection
Quantitative Selection Lab
Wisconsin Fast Plants
6 weeks generation time, 2-3 weeks to flowers

HIV – A Case Study for Evolutionary Thinking

Two distinct epidemics
Homosexual men in North America and Western Europe
Heterosexual men and women in South Africa and Southeastern Asia

January 28, 2014

HIV
Retrovirus
Change RNA to DNA (has to come from the virus)
Virus uses own enzyme to insert itself into the host DNA
RNA  DNA transcriptase (reverse transcriptase)
Host-specific to macro-phages, T-cells
AIDS: Acquired Immune Deficiency Syndrome
Treatment with AZT
AZT: Nucleotide analog
Reverse transcriptase mistakes AZT for Thymidine
Terminates transcription
No viral reproduction
Worked very well for some time
Reverse transcriptase: 50% of DNA-transcripts contain mutations
Mutations in gene fro reverse transcriptase
Some do not mistake AZT for thymidine
Replicate in presence of AZT
New, AZT- resistant strain for HIV
Four steps were involved:
Mutations in reverse transcriptase gene
Mutation result in variability among virions
Some virions survive better in presence of AZT than others
Mutations are passed on to offspring
Result
Genetic composition of HIV population changed over time
Evolution by natural selection
When did mutations occur relative to AZT treatment?
Mutations happen spontaneously and randomly
Selections acts on existing variability
Definition of Evolution
Change of the genetic composition of a population over time
Change of allele-frequencies in a population between generations
Natural Selection
Darwin’s 4 postulates of Natural Selection…