BIOL 2040 Lecture Notes - Lecture 2: Virus, Common Descent, Meiosis
27 Apr 2018
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Lecture 2 - Intro to Evolution (end)
January 14, 2018
5:12 PM
Selection does not create variation
Virulence to T-cells
• CCR5 co-receptor
o After the initial infection, virions that have CCR5 co-receptors are attacked first
o As infection progresses, there are less and less CCR5-virions
• CXCR4 co-receptor
o More of these virions exist now, after most of the CCR5-virions are being destroyed
o Virions with this receptor gains an advantage - because they are now more common
o These virions are disfavored because their speed of reproduction is slower, compared to the
CCR5-virion
o This is the virion that drives down the T-cell count, and essentially kills the host
CCR5 favored first, then after they're gone, the CXCR4 is favored. They achieved selection, because
they are the favored virion at the end, though they eventually kill off the host, wiping themselves out.
"Theory"
• A scheme or system of ideas or statements held as an explanation or account of a group of facts or
phenomena
• A hypothesis that has been confirmed or established by observation or experiment, and is
propounded or accepted as accounting for the known facts
Evolution is:
• A process that occurs whenever the conditions are met
o Variation, inheritance and selection
o Common ancestry with different environments
• A fundamental principle of biology
• A process that can be studied scientifically
o Hypothesis can be tested against evidence
• Unguided
o Variation occurs at random
o Variation occurs before selection
o No foresight, planning, or purpose
Evolution is NOT:
• A force that determines our actions
• A moral prescription for our actions (a moral code)
• An explanation of "meaning" or "purpose" to life
• A philosophy, an ideology
Analogy to physics and ethics: a guy is drowning, and someone sees, and wants to save them. It is
obvious that they would rather throw the life raft than an anchor.
• Understanding a process does not dictate our actions
• Understanding the process is knowledge that can be applied to get a desired outcome
find more resources at oneclass.com
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Document Summary
Ccr5-virion: this is the virion that drives down the t-cell count, and essentially kills the host. Ccr5 favored first, then after they"re gone, the cxcr4 is favored. They achieved selection, because they are the favored virion at the end, though they eventually kill off the host, wiping themselves out. Evolution is not: a force that determines our actions, a moral prescription for our actions (a moral code, an explanation of meaning or purpose to life, a philosophy, an ideology. Analogy to physics and ethics: a guy is drowning, and someone sees, and wants to save them. Things to know from 1st year genetics (things expected to be remembered) Independent assortment: aa x aa --> aa, aa x aa --> 1aa:2aa:1aa. Intro to population genetics: hardy weinberg equilibrium: by yule, punnett, g. h. hardy, wilhelm weinberg, gene pool: all individuals in a generation. If 60% are a, and 40% are a, for alleles, the frequency would be 0. 6 and 0. 4: ex.
