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Unit 4

Chapter Overview
During this unit, students investigate homeostasis and the movement of molecules in relation to the cell. This unit provides a knowledge base crucial for subsequent units.  Cellular processes are generally addressed during this unit
when comparing and contrasting prokaryotes and eukaryotes.  The cellular processes involved in transport of molecules are explicitly addressed in depth in this unit.

Main Ideas
***All living organisms are composed of prokaryotic or eukaryotic cells, which contain structures that carry out specialized functions.
***Different substances move across the cell membrane by diffusion, osmosis, active transport, endocytosis and exocytosis to maintain homeostasis.

***Students may think in terms of only two kinds of cells- plant and animal, rather than knowing that there are many types of prokaryotic and eukaryotic cells.
***Students may think all cells look exactly the same or that animal cells always have a circular shape and plant cells always have a rectangular shape, rather than knowing that there is diversity in cell structure and that this structure is closely related to the cell’s function.


Prokaryotic – small, unicellular, no nucleus or other membrane bound organelles

Eukaryotic – large cell with a nucleus and other membrane bound organelles

Homeostasis – balance, stays the same even if outside conditions change

Diffusion – particles move from high concentration to low concentration

Osmosis – water moves from high water concentration to low water concentration across a selectively permeable membrane

Active Transport – particles are pumped from low concentration to a higher concentration

Specialized Cell – cell that is a special shape so it can do a specific job

Atom – smallest unit of an element

Molecule – two or more atoms that are held together by chemical bonds

Organelles – parts of a cell

Cell – smallest unit of life, basic unit of structure and function in living things

Tissue – a group of similar cells that work together to do a job

Organ – a group of different tissues that work together to do a job

Organ System – a group of different organs that work together to do a job 

Organism – a living thing, can be made of many organ systems working together OR one cell

Other Valuable Resources

Amoeba Sisters: Pro/Eukaryotes

Cell Structures

Crash Course: Organelles

Amoeba Sisters: Cellular Transport

Crash Course: Cellular Transport