Unit 3
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.
Misconceptions
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.
Vocabulary
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
Notes
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