Histo Lecture 3
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Definition of Diffusion
Movement along concentration graident (high to low conc.); no ATP required
Direct passage through membrane
Utilizes membrane protein for import
Requires energy; typically moving against concentration gradient
2 Types of Active Transport
Primary and Secondary
What materials can pass directly through phospholipid bilayer?
Lipid soluble molecules
e.g. Oxygen, carbon dioxide, alcohol
Some water soluble molecules (water, proteins, some ions) pass through the cell membrane using ______ ______ pores
Name 3 of the 6 factors that can influence Simple Diffusion
- -Amount of substance availability
- -Lipid solubility of diffusing substance
- -Number and size of membrane opening (channels)
- -Velocity of kinetic motion of molecules (greater temp = faster diffusion)
- -Molecular weight - smaller particles move faster
- -Distance- shorter distance = faster diffusion
Nickname for Facilitated Diffusion
Carrier mediated diffusion
Facilitated Diffusion requires interaction with what type of protein?
How do carrier proteins move molecules through the membrane?
- -No energy required
- -Conformational change in protein causes molecule to move through membrane
- -Molecule must be moving along concentration gradient
- Net movement of water along its concentration gradient
- (Requires semi-permeable membrane!)
Driving force for osmosis across a membrane
Osmotic pressure behavior in solute concentrations
- -Directly related to solute concentrations of two fluids in compartments
- -Water tends to move from low to high solute concentration
Force that water transmits via its weight or via its flow through a vessel.
Tends to eualize with osmotic pressure to prevent too much loss/gain of water from cells/tissues
What is Active Transport?
Transport of substances across cell membrane which require energy expenditure
Types of molecules carried in Active Transport
Ions and large molecules (sugars & proteins)
Primary Active Transport
Direct utilization of ATP as energy source
Secondary Active Transport
Energy comes from stored energy of ionic concentration gradient between intra/extracellular environments
Both Primary and secondary active transport utilize what type of protein?
Sodium Potassium Pumps
-Important for maintaing voltage across the cell membrane
Both molecules required for binding to protein must be present for transport to occur
- Molecules are transported in opposite directions across the cell membrane.
- -Sodium potassium pump
Passage of material into a cell moving through cell membrane
3 Types of Endocytosis
- -Receptor Mediated Endocytosis
Uptake of particular material
Only "recognized" particles are engulfed
Uptake of soluble molecules (water)
Non-specific engulfment of molecules
Receptor Mediated Endocytosis
Uptake of specific molecules using specific membrane proteins (clathrins)
Secreting proteins made by cell
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