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Characteristics of Life:

Homeostasis: maintenance of internal stability, body responds to internal and external changes

Metabolism:  combinations of all the chemical reactions that occur in an organism.

Life Functions
Respiration  the   ability to convert food into energy
Regulation  the   ability to maintain a stable internal environment (maintain homeostasis)
Reproduction  the   ability to produce more of their own kind (not needed for the individual   organism to survive)
Growth  the   ability to increase in size
Excrete  the   ability to remove metabolic wastes (Carbon Dioxide, Water & Urea)
Nutrition  the   ability to obtain and process food (Autotrophic or Heterotrophic)
Transport  the   ability to move materials into, out of and throughout an organism
Synthesis  the   ability to manufacture materials not able to be gotten from the environment


Cell Structure

A. Cell Theory states the following:

  1. All living things are composed of cells.
  2. Cells are the basic unit of structure and function in living things.
  3. New cells are produced from existing cells.

Cytoplasm- liquid in cell

Nucleus- contains genetic information (Protein Synthesis)

Vacuoles- stores food, wastes

Mitochondria- cell energy, respiration, ATP

Chloroplast- photosynthesis (plant cell only)


Cell wall- plant cell only, provides structure to the cell

Cell membrane- controls what enters and leaves the cell

Cell membrane consists of;

  1. Double layer of lipids (phospholipids)
  2. Proteins imbedded in lipids
  3. Carbohydrates chains project from proteins.

Carbohydrates part of membranehelps with cell communication.  Lipid part of membrane allows small molecules to pass through easily.  For examples; water carbon dioxide, and oxygen.  Protein portion of cell membrane allows glucose and amino acids into and out of the cell.

Types of Transport
1.   Passive Transport
–      Movement of material without energy
–      Molecules move from high concentration to low concentration.
–      Types of passive: diffusion & osmosis

Diffusion– spread of molecules from higher to lower concentration.  (small molecules: CO2, O2)
Osmosis – diffusion of water through a membrane.

 2.  Active Transport
–      Movement of materials that requires energy (ATP)
–      Only move through proteins
–      Moves from low concentration to high concentration.
–      Types of active: endocytosis (pinocytosis, phagocytosis), and exocytosis



Photosynthesis takes place in the chloroplast of plant cells and makes food for the cell.  This process produces both oxygen and gluse as show in the diagram.  The formula of photosynthesisis as follows:  cabron dioxide + water –> glucose + oxygen.  The glucose will be used as food for the plant and the oxygen is released into the atmosphere.

Respiration on the other hand occurs in the mitochondria of both autotrophic and heterotrophic cells.  This formula is the reverse of the earlier mentioned photsynthesis formula.  Respiration formula:  oxygen + glucose –> carbon dioxide +ATP