CHAPTER 3 GUIDE: Cell Structure and Function
LEARNING OBJECTIVES
What structural features are shared by all cells?
Cell membrane (plasma membrane) – phospholipid bilayer +
proteins, forms a boundary
Cytoplasm – aqueous interior
DNA – hereditary information
Ribosomes – make proteins
What are the key differences between prokaryotic and
eukaryotic cells?
Prokaryotic cells:
Small, simple, no nucleus, DNA floats in the nucleoid region, and
Few or no membrane-bound organelles
Example: Bacteria, archaea
Eukaryotic cells:
Larger complex, DNA in the nucleus, and Many membrane-bound
organelles
Example: Animals, plants, fungi, algae
How do solutes and water cross membranes?
Simple diffusion – small, nonpolar molecules (O₂, CO₂) move
freely
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Facilitated diffusion – large/polar/charged molecules cross with
the help of transport proteins (no energy)
Osmosis – water moves across the membrane from low solute →
high solute concentration
Active transport – solutes pumped against a gradient using ATP
and transport proteins
Bulk transport – vesicles move huge molecules
What determines the direction of movement of solutes and
water in different situations?
Concentration gradient (high → low)
Tonicity of solution compared to the cell:
Hypotonic → cell swells/bursts (more water enters)
Hypertonic → cell shrinks (water leaves)
Isotonic → no net movement
How do antibiotics target bacteria?
They target features unique to bacterial cells, thereby killing
bacteria but not human cells.
What are some key eukaryotic organelles and their function?
Nucleus – houses DNA, the control center
Endoplasmic Reticulum (Rough ER) – protein synthesis
(ribosomes attached)
Smooth ER – lipid synthesis
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CHAPTER 3 GUIDE Cell Structure and Function.pdfCHAPTER 3 GUIDE Cell Structure and Function.pdf 2026/2027
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