BioSec 2012: Cheryl

Chapter 1: Light and Life

• Light
  • source of information and energy
  • Defined as EM radiation
  • Wave of photons
  • Can be absorbed by pigments and then used
  • Colour = light that is not absorbed by pigment
• Electrons become excited when absorbed by light which in turn then becomes potential energy (photosynthesis)
• Photoreceptor
  • light-sensing system
  • made up of pigment molecule bound to protein
  • eye = organ of animals to sense light
• Problem:
  • most light driven processes can only process a certain part of the EM spectrum
  • source of energy…too much can cause deadly effects
  • pigment melanin in our skin absorbs UV (high energy and can be damaging)
• Circadian rhythms (body clock) the daily cycle of most living organisms have evolved to adapt to the change in light (night and day…plant use photosynthesis during the day and night break glucose)
• Some animals prefer the dark (nocturnal animals like moths)
• Some animals have ancestors that had functional eyes but are not blind (blind mole rat)
• bioluminescent: organisms that use chemical energy to make their own light to attract a mate, camouflage, attract prey or communicate

Chapter 2: origins of Life

• life defined by seven characteristics:

1. Display order

   high ordered structures

2. Harness and utilize energy: getting and using chemical energy to power the organism’s activities
3. Reproduce: ability to reproduce their own kind
4. Respond to stimuli: ability to respond environmental stimuli
5. Exhibit homeostasis: ability to control an organism’s internal environment within the limits to sustain life
6. Growth and development: consistent growth and development (DNA inheritance)
7. Evolve: adapt to environments over many generations to have better reproducibility and survival of the species.

• Cell theory

1. All living organisms are composed of cells
2. Cells are the functional units of life
3. New cells come only from preexisting cells (division)

• Eukaryotic Cells