Levels of Organization
• Atom Level
• Tissue Level
• Ecosystem Level
• Molecule Level
• Individual Level
• Organelle Level
• Organ System Level
• Cell Level
• Community Level
• Population Level
• Organ Level
• Atom Level
• Molecule Level
• Organelle Level
• Cell Level
• Tissue Level
• Organ Level
• Organ System Level
• Individual Level
• Population Level
• Community Level
• Ecosystem Level
MoleculeCombinations of atoms
that are bonded together
AtomThe fundamental unit of
all matter
Organelle A subcellular membrane-
bound compartment
Cell
Tissue
Organ
The basic unit of life
Group of similar cells that
perform a common function
Two or more different tissues
that perform a common
function
PopulationAll individuals of the
same species that
occupy a given area
Organ
System
Individual
Group of related organs that
have a common function
A single organism
Community
Ecosystem
All the species in an
ecosystem that can
interact
A community and its
physical environment
The Ingredients of Life• Elements- substances composed of only one type of atom.
– 94 naturally occurring.
– Carbon, Nitrogen, Hydrogen, and Oxygen account for 90% of the elements in living things.
Eukaryotic vs. Prokaryotic Cells
Feature Eukaryotic ProkaryoticOrganisms Animals, plants Bacteria, Archaea
Size 10-100 µm 1-10 µm
Organelles Yes No
DNA form Coiled, linear Circular
DNA location Nucleus Cytoplasm
Internal membranes Yes No
Cytoskeleton Yes No
Cell Theory
• CELL THEORY- proposed in 1839 by Schleiden
and Schwann.
1. All living things are composed of cells.
2. The cell is the basic unit of life.
3. New cells arise only from preexisting cells.
4. Cells contain hereditary information which is passed
from cell to cell during cell division.
5. All cells are similar in chemical composition.
6. All of the energy flow of life occurs within cells.
Invention of the Microscope
• Invented circa 1595 AD by
Zacharias Janssen (1580-
1638), a spectacle maker
from Holland.
4 Types of Microscopes Used to Study Cells
• Dissecting microscope- 4-50X.– Light is passed through or reflected on a specimen.
– Focus with a set of glass lenses.
• Compound light microscope- 1,000X.– Light is passed through a specimen.
– Focus with a set of glass lenses.
• Transmission electron microscope- 50,000X.– Electrons are passed through a specimen.
– Focus with a set of magnetic lenses.
• Scanning electron microscope- 10,000X.– Electrons are scanned over the surface of a specimen that has
been coated with a metal.
– No Focus, produces a three-dimensional image collected from electrons that are emitted from the metal.
Diffusion
• Diffusion- the
spontaneous tendency of
a substance (solute or
solvent) to move from a
more concentrated to a
less concentrated area.
– T or F. Diffusion results in
the uniform distribution of a
substance.
Osmosis
• Osmosis- the diffusion of water through a selectively permeable membrane from a region of higher concentration to a region of lower concentration.
When referring to two solutions that are separated
by a selectively permeable membrane:
• Isotonic solutions have the same
concentration of solute as the cell.
• Hypotonic solutions have lower solute
concentrations than the cell.
• Hypertonic solutions have higher solute
concentration than the cell.