Download 7.3 From Cell To Organism

7.3 From Cell To Organism
I. Diversity in Cells
A. Prokaryotic Cells
1. Always unicellular
2. Limited in size
3. Lack nucleus & membrane bound organelles
4. Vary in cell wall composition & ability to move
a. many have a flagella
b. flagella – long thread-like structure that
rotate quickly to move an organism
c. pili – short, thick outgrowths that
allow attachment to surfaces or other cells
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B. Eukaryotic Cells
1. Vary in size
2. Can be unicellular or multicellular
3. Examples – plant & animal cells
a. Both have same organelles
b. Plant cells also have chloroplasts,
a large central vacuole, & a cell
wall
4. Can become specialized in function
a. examples – muscle cells,
nerve cells, skin cells, etc.
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II. Levels of Organization
A. Tissues
1. A distinct group of cells that have similar
structures & functions
a. ex- muscle tissue
B. Organs
1. A specialized structure with a specific
function made up of many different tissues
a. ex – the heart - made up of muscle, nerve,
& other tissues
C. Organ System
1. Various organs that carry out a major
body function
a. ex- circulatory system – carries blood
throughout the body
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III. body types
A. More than half the biomass on Earth is
composed of unicellular organisms
B. Cell Groups
1. Colonial organisms
a. cells that live as a connected group but do
not depend on each other for survival
i. ex.- coral reefs
C.. Multicellularity
1. Only occurs in eukaryotes
2. Includes some protists, most fungi, & all
plants & animals
3. Begin as only one cell & divide
4. Undergo differentiation – the process by
which specialized functions are created
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