Levels of Cellular Organization
BY MS. ETHRIDGE, MS. MILSTEAD, MS.
MYERS, MS. PALERMO
Objectives
 Define cell organization.
 Illustrate levels of cell organization.
 Differentiate types of cell organization within the
body.
Key Terms
 Cell: The smallest organized unit of a living
organism.
 Organelle: A structure inside the cell that helps it
survive.
 Protoplasm: All the living material found in a cell
capable of carrying on all the life processes.
Why is Cellular Organization Important?
 Living organisms need to do things in order to
survive.
 Different parts of the body take care of chores to
keep itself running.
 All parts work together in harmony to keep the
animal alive.
Atom
 The most basic unit of matter.
 Essentially the building blocks of everything in the universe.
 Can be neutral, negative, or positively charged
 A group of atoms is called a molecule
Molecule
 A group of two or more atoms held together with a
neutrally charged covalent bond.


May consist of like atoms (O2) or several different atoms (H2O)
Too small to be seen with the naked eye
Cell
 Basic structural and functional unit of all living
organisms.



Smallest classified living thing.
“The Building Block of Life”
Can be single celled or multicellular
 Two types: Prokaryotic and Eukaryotic
 Prokaryotic are usually independent
 Eukaryotic are inside multicellular organisms
Tissue
 A group of cells (not necessarily identical) that
perform the same function.

Four types of animal tissue: Connective, Muscle, Nervous, and
Epithelial
Connective Tissue
 Fibrous, nonliving material
 Gives shape to organs and holds them in place.
 Examples: Blood and Bone
Muscle Tissue
 Most active tissue
 Contractile: has the ability to contract and expand
 Produces force and movement
 Separated into three different categories:
 Visceral/Smooth: inner lining of organs
 Skeletal: Attaches to bones to create movement
 Cardiac: Found in the heart used to pump blood throughout
the body
Nervous Tissue
 Transmits communication throughout the body.
 Two Types:
Central Nervous System: Forms the brain and spinal cord
 Peripheral Nervous System: Cranial Nerves and Spinal Nerves as
well as the motor neurons

Epithelial Tissue
 Covers organ surfaces
 Provides barrier between exterior and interior of organism
 Can specialize in secretion and absorption
 Protection from microorganisms, injury, and fluid loss
Organ
 A group of tissues joined together to serve a common
function.

Classified into two types:
Parenchyma: Main tissue, unique for the specific organ Ex.
Myocardium in the heart
 Sporadic: Stroma, Include nerves, blood, and connective tissues

Organ System
 Also called a biological system or body system
 Two or more organs working together to perform a specific
task
 Ex. Muscle and Skeletal create Musculoskeletal System
 Eleven major organ systems in animals:

Circulatory, Digestive, Endocrine, Excretory, Immune,
Integumentary, Muscular, Muscular, Nervous, Reproductive,
Respiratory, Skeletal
Organism
 A contiguous living system such as an animal or
plant. It is a complex system that has the ability to
reproduce and sustain life.
Review
 Define cell organization.
 Illustrate levels of cell organization.
 Differentiate types of cell organization within the
body.