Unit 1

• Characteristics of Life

  • Requires ATP
  • Adapts and evolves
  • Responds to stimuli
  • Displays heredity
  • Reproduces
  • Made of cells
  • Maintains homeostasis
• ATP (Adenosine Triphosphate)

  • Used for energy in cells
  • Breakdown of bond between 2nd and 3rd phosphate provides energy
• Made of cells

  • All living things are composed of organized units
• Require energy

  • All living things obtain and use energy to facilitate basic life processes.
  • Unit of energy is ATP.
• Reproduce

  • All living things have the ability to reproduce themselves, or their cells, through asexual or sexual means.
• Display heredity

  • All living things contain and exhibit genetic information received from parents.
• Adapt and evolve

  • All living things, and populations of living things have the mechanism to become better suited to new environments
• Response to stimuli

  • All living things can change their processes, state, or activities as a result of exposure to a phenomenon
• Maintain homeostasis

  • All living things have the ability to preserve a constant, consistent internal balance when faced with different conditions.
• Homeostasis is how an organism mantains their internal environment.
• Homeostasis maintains optimal cellular function.
• The hypothalamus is important for homeostatic function.
• Dynamic equilibrium is a condition that stays stable within functioning limits.
• Negative feedback mechanisms are mechanisms used to maintain homeostasis by counterbalancing changes.
• Sensors

  • Detect variation from the set point
  • Send signals to the control center
• Control Center

  • Interprets input from sensors
  • Directs output in effectors
• Effectors

  • Enact action to change conditions
  • Muscle or gland
• Plasma membrane

  • A thin flexible boundary between a cell and it's environment that allows nutrients into the cell and waste / other products to leave
• Selective permeability

  • Allows some substances to pass through while keeps others out
• Phospholipid bilayer

  • 2 layers of phospholipids arranged tail to tail
• Fluid mosaic membrane model

  • The structure of the plasma membrane as a mosaic of components that gives the membrane a fluid character.
• Membrane cholesterol

  • Maintains stability and regulates membrane structure
  • Prevents freezing and melting
• The activities of a living cell depend on the ability of it's membrane to:

  • Transport raw materials in
  • Transport products + waste out
  • Prevent unwanted matter in
  • Prevent needed matter out
• The membrane is responsible for maintaining cell homeostasis.

  The complex nature of the membrane allows it to be selectively permeable.
• Extracellular Environment

  • The liquid that surrounds cells is the solvent for chemicals transported accross the membrane.
• Passive Transport

  • Movement of molecules across a cell membrane without the expenditure of energy.
  • No ATP is used.
  • Examples include diffusion, osmosis, and facilitated diffusion
• Diffusion

  • The movement of molecules down a concentration gradient.
  • From areas of high concentration to low concentration across the membrane
  • Random movement
• Factors that affect movement across the cell membrane:

  • Temperature
  • Surface area
  • Polarity
  • Molecule size
  • Concentration gradient
• Proteins can freely move in the phospholipid bilayer.
• Homeostasis is how an organism manrains their internal environment stable.
• The phospholipid bilayer allows cells to live in a watery environment.
• Transport Proteins

  • Proteins that span the phospholipid bilayer
  • Moves substances, waste
• Concentration Gradient

  • The difference in concentration of a substance between two sides of a membrane
• Osmosis

  • Diffusion of water through a semipermeable membrane
• Isotonic

  • Cell and solution have the same solute concentration
  • Moves at the same rate in and out
• Hypertonic Solution

  • The solution is more concentrated than the cell
  • Water exits the cell via osmosis
• Hypotonic Solution

  • The solution is less concentrated than the cell
  • Water enters the cell via osmosis
• Cell membrane properties:

  • Fluid
  • Flexible
  • Self sealing
  • Semipermeable
• Blood pH: How acidic/basic blood is
• Passive transport requires no energy, while active transport uses ATP