Cell Specialization Notes
Chelsea Thinks Of Several Organisms – use this sentence to help your remember the order
1. In single-celled organisms, like bacteria, the single cell does ALL the jobs needed to keep the
organism alive.
2. In multi-celled organisms, cells do ONE specific task or job for the organism.
a. In multi-celled organisms there is a division of labor, the work of keeping the organism alive is
divided between the different parts of the body.
b. Each cell has one specific job to do and all cells work together to keep the living thing healthy
and alive.
3. The order of specialized parts in a living thing is called the levels of organization.
4. There are 5 basic levels or organization – starting with the smallest and simplest (cells) and going to
the largest and most complex (organism) and each level of organization works with every other level.
5. CELL – LEVEL 1
a. Cells are the basic unit of structure and function of all living things.
c. Examples: red blood cell, animal cell, plant cell, heart cell, leaf cell, stem cell, sperm cell
6. TISSUE – LEVEL 2
a. Tissues are groups of cells joined together that are similar in structure and function.
b. Each tissue cell must carry on ALL the functions and activities needed to keep the cell alive.
c. Tissues also perform one or more specific jobs.
d. Examples: blood, nerve, skin, muscle tissue, heart tissue, bone tissue, brain tissue, leaf tissue,
stem tissue, root tissue, lung tissue, etc
e. Blood is the only liquid tissue in the human body.
7. ORGAN – LEVEL 3
a. Organs are groups of different tissues that work together. They control an organ system.
b. Examples: heart (circulatory system), lungs (respiratory system), brain (nervous system),
bone (skeletal system), muscle (muscular system), skin (skin system), kidney & bladder
(excretory system), stomach (digestive system), ovaries or testes (reproductive system), root,
leaf, stem for plants
c. Heart is made up of 3 tissues working together – muscle tissues, blood, and nerve tissues
8. ORGAN SYSTEMS – LEVEL 4
a. Organs systems (also called systems) are groups of organs working together to do a certain job
or function.
b. Organ systems vary in number and complexity from one kind of living things to another
c. Examples: skeletal (supports & protects body), muscular (controls movement), skin (protects
outside of body), digestive (breaks down food), circulatory (moves blood through body),
respiratory (controls breathing), excretory (gets rid of waste), endocrine (makes chemicals),
nervous (controls senses and thinking), reproductive (makes babies), flower (in plant – makes
seed or baby plants)
9. ORGANISM – LEVEL 5
a. An entire living thing that carries out ALL the basic life functions is an organism.
b. Examples: buttercup, deer, dolphin, maple tree, grass, human, single-celled bacterium, amoeba
c. Organisms are a combination of organ systems – each system doing its own job and working
wither all the other organ systems to keep the organism alive.