Chapter 10: Biochemistry of the Genome

Chapter 10: Biochemistry of the Genome

\ Hammerling's Experiment

  • Experimented with the eukaryotic alga Acetabilaria

  • Cuts the cap and looks at the foot

  • A new cap regenerates

  • Then he removes the foot

  • There are no new foot that's regenerated

  • Concluded that the nucleus was housed in the foot

Next step

  • The next goal was to show the nucleus was what determined the morphology of the cell
  • Add more

Beadle and Tatum

  • Worked with Neurospora crassa

  • Minimal media: not every organism can grow on there

  • Only wild-type (natural)

  • Building blocks present, but not amino acids

  • Complete media: allows even the worst thing(organism) to grow

  • Has everything and more for an organism to grow

  • Has all the amino acids

  • The first step before minimal media

  • Hypothesis 

  • Each one of the enzymes is controlled by one gene

  • Trying to find out how many genes it takes to make it an enzyme

Griffith’s transformation experiment

  • Worked with 2 strains of streptococcus pneumoniae

  • Takes the smooth string(which is dead)

  • Mouse lives

  • Takes rough strain(alive) and smooth strain

  • Mouse dies

  • Takes smooth string (from the previous mouse)

  • Mouse dies

Avery Et

  • Determined that transformation occurred in absence of RNA and protein but not DNA
  • Concluded that DNA was the material that was passed (hereditary component)

Hershey and Chase 

  • Used Radio active phosphorus and sulfur in the bacteria to track it
  • Phosphorus was with DNA and sulfur was with protein
  • Finally established that DNA is the hereditary material

\ DNA

  • Nucleotides are the building blocks of DNA

  • 3 parts to DNA

  • Phosphate group

  • 5 carbon sugar

  • Nitrogenous base

  • DNA strands are antiparallel

  • 5’ prime to 3’ and 3’ to 5’

  • A=T, G=C

  • double helix

  • Always written as 5’ to 3’

  • Heat can split the DNA (PCR)

RNA

  • Have uracil in RNA, not in DNA

  • Single-stranded

  • 3 types of RNA

  • Messenger RNA (mRNA)

  • Photocopy of genetic information

  • Ribosomal RNA (rRNA)

  • Makes up ribosome (60% wt)

  • Transfer RNA (tRNA)

  • Carries correct amino acids to the ribosome to build protein chains

\ Compare and contrast the 4 methods bacteria use to achieve genetic diversity

  • Conjugation

  • Transfer of DNA through direct contact using conjugation pilus

  • Transduction

  • Mechanism of horizontal gene transfer in bacteria in which genes are transferred through viral infection

  • Transformation

  • Mechanism of horizontal gene transfer in which naked environmental DNA is taken up by a bacterial cell

  • Transposition

  • Process whereby DNA independently excises from one location in a DNA molecule and integrates elsewhere

Other stuff

Mendel and his Pea Plants 

  • demonstrate independent and consistent transfer of traits

  • Why peas?

  • They self-fertilized and were inbred enough to produce what was called true-breeding plants

  • To fully understand how traits were passed on, the plants needed to breed true to their parents

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