Understanding Cell Transport: Osmosis, Diffusion, and Membrane Dynamics
This lesson covers essential concepts of cell transport mechanisms, including osmosis, diffusion, and active transport. We will review homework, emphasizing the importance of proteins in various transport roles, including enzymatic and receptor functions. Students will also learn about the specialized functions of organelles like lysosomes, mitochondria, and chloroplasts. The session prepares students for a quiz on Monday and a mini-test on Wednesday, focusing on key processes like facilitated diffusion and bulk transport through endocytosis and exocytosis.
Understanding Cell Transport: Osmosis, Diffusion, and Membrane Dynamics
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Presentation Transcript
Agenda • Have HW out for stamping • Current Event • Go over HW • Osmosis/Diffusion • End/HW: Osmosis/Diffusion Wksht • Quiz Monday Mini-Test Wednesday
2 • Grease is hydrophobic H O H H O H H O H H O H
5. • Small Non-polar > Small polar > Large polar > ion
6/7 • Proteins: • Transport, reception, anchors, enzymes, etc. • Carbs: • Tags/markers/identification
8. • Specialization. Each organelle/cell is unique in what it contains and highly specialized
9. • Lysosome – holds in digestive enzymes, protein channels for taking in things to digest • Mitochondria – ATP synthase, channels for NAD+, ADP, Glucose/Pyruvate etc. • Chloroplast – Chlorophyll, ATP synthase, NADP+, ADP, etc. • Nucleus – lets few things in except for some messengers, lets RNA out • White blood cell – proteins and carbs for recognizing foreign cells
10. Walls Membranes Phospholipids Filters • Carbs (cellulose etc.) • Structures
Osmosis, Diffusion, Active Transport and Bulk Transport CELL TRANSPORT
Diffusion • Things spread out • Move from more concentrated to less concentrated
Passive Transport • Things diffuse across the membrane • If they are able to cross
Facilitated Diffusion • Transport proteins allow polar molecules and ions to travel down concentration gradient • No usage of energy! • Aquaporins – special protein channels for water Peter Agre won the 2003 Nobel Prize for the discovery of aquaporins!
Active Transport • Some transport proteins pump molecules against their concentration gradient • Requires energy (ATP)
Bulk Transport • Many molecules are too large to pass through the membrane • i.e. proteins • They enter the cell through endocytosis and exocytosis
Endocytosis • The cell intakes large molecules by forming new vesicles • Small area of membrane sinks inward, forming a pocket which eventually pinches off
Exocytosis • Vesicle fuses with plasma membrane, expelling contents from the cell • Vesicle membrane becomes part of plasma membrane
Osmosis • Special case of water diffusing • Wherever a solution is less concentrated with solutes, it is more concentrated with water
