Wednesday, October 30, 2013

Reading Assessment: Chapter 6 Survival of Sickest


First vaccine
cowpox
resistant to smallpox

make other people resistant by putting it on teenage boys
-worked

how vaccination works
begins with harmless version of virus 
-bodies will recgonize but not enough to cause seriou disease
-immune system produces antibodies that defnd against virus
-then if we are exposed to harmful version, our bodes are prepared to fight

different antibodies to fight off different attacks

First cell
-genetic instruction to mnufacture proteins to build human being
instructions carried out by nucleotides
-nucleotides= dna base pair
-genes  organized in 23 pairs
every pair except 23rd (sex chromosome) is a matched pair
-chromosome carries the same instructions 
-always have dominant gene over recessive

germ cells-cells that combine to provide offspring

3% dna is meant for building
97% isnt active in building

97% portion of genome plays role in evolution 
-called noncoding DNA
-made up of jumping genes
-related to viruses

mitochondria= produce energy to run cells
-live in all cells
-own heritable DNA

evolution shaped by integration and adaptation of viruses

Theory
genetic chnages product of accidental mutations (rearrange DNA)
-mutations happen when there is an error
-mutations happen when organism exposed to radiation or powerful chemicals
-sun cause mutation
sunspot peaks- energy leaked through magnetic field
occurred during massive flu outbreaks
-antigenic drift- mutation occurs in the DNA of a virus
-random mutation= advantage on its carrier, better chance to live
one species advantage could be anothers disadvantage (ie. virus to humans)

theory wrong: evolution favor a mutation that helps an organism discover adaptations to help survive

single genes have capacity to produce different proteins at once
shuffle/reshuffle to produce array of proteins

complexity- combining parts of one gene with another

not instructions anymore, scientists learn genes are an intricate network of info

McClintock
corn plants experiment
when they were stressed: DNA moving from one place to another (inserting themselves)
-affected nearby genes- turned them on and off

method:
  1. relocated to specific parts of genome
  2. mutations triggered by outside influences (environment)

discovered “jumping genes” (transposons)
-suggested evolution could be faster than imagine
-mutations aren’t just random

Remain in an active gene after inserted and make a difference

Example: jumping gene one one line of fruit flies turned them into superhero fruit flies
-resist starvation 
-withstand high temp
-life expectancy that was 35% longer

genome gambles on mutation

Cairns 
E coli- digestive workhorse in humans 
*cannot digest lactose
-starvation is a big threat to bacteria

experiment: deprived E coli of any food except lactose
  • bacteria developed mutations that allowed them to lose their lactose intolerance
idea: bacteria targets specific area of their genome where mutations could be an advantage to them



argument idea:
hypermutation- mutation on steroids
helped bacteria produce mutations 100 times faster
-suggests genome has ability to order mutations on demand

Weismann barrier

germ plasma theory- divides the body’s cells into groups
every cell (except germ cell) is a somatic cell

theory: info in somatic cell is never passed on to germ cells
but: some viruses may be able to penetrate the barrier and carry DNA fro somatic to germ cells 

germ line mutations- mutations result in a different gene in egg or sperm that produces new trait in offspring

cancer- uncontrolled cell growth caused by mutation in the gene that is supposed to control the growth of cancerous cells

jumping genes help humans in two ways (diversity):
  1. very active in brain development 
  2. immune system 

Antibodies 
b-cells- building blocks for antibodies

V(D)J recombination: b-cells seek out instructions for antibody in their DNA, snip away line of instruction for other antibodies and sew rest together
(unlike jumping genes because leaves a little loop) 

once antibodies are developed, you always have them 
-immune to future infections 

Viruses
cannot produce on its own
hijack hosts cellular machinery

retrovirus-offspring born with virus permanently in DNA

HERVs-permanent place in DNA


two different types of jumping genes:
DNA transposons- cut and paste
retrotransposons- copy and paste

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