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Jiang_Hui(Vivian)_Block 5_MM3 (Plasma Membrane (Parts of Membrane…
Jiang_Hui(Vivian)_Block 5_MM3
Plasma Membrane
Parts of Membrane
Membrane Proteins
Peripheral protein: loosely bound to the surface of the membrane or the revealed part of integral proteins
Integral protein: transmembrane proteins that span the membrane
Channel protein: opens up passage ways for molecules to go through
Carrier protein: opens up to deliver molecules but only one side is open at a time. Unlike channel protein that opens to both sides of the membrane.
Phospholipid Bilayer
Amphipathic Molecule: phospholipid
Cholesterol: membrane structure
Glycoprotein: They can act as receptors and aid membrane structure
Glycolipid: Aid membrane structure and cell-to-cell recognition
Protein Channel: allows molecules through
Cytoskeleton Filament: membrane structure
Types of Transport Through Plasma Membrane
Passive Transport
Types of Passive Transport
Facilitated Diffusion
Non specific transporter: opens up and allows molecules to go through
Specific Transporter: opens up to allow particle to go through
Simple Diffusion: molecules go directly through the membrane; particles move from high to low particle concentration
molecules: hydrophobic substances and small uncharged polar molecules
Osmosis: movement of water from low to high particle concentration
Aquaporin: channel/intergral protein for water
Effects of Osmosis on Cells (like animal cell)
In Isotonic Solution: The cell will remain normal
In Hypertonic Solution: the cell will shrivel
In Hypotonic Solution: the cell will burst
Effects of Osmosis On Plant Cells
In Isotonic solution: flaccid
In Hypotonic solution: turgid (strong & best form)
In Hypertonic solution: plasmolyzed
Doesn't require energy (ATP)
Active Transport
Types of Active Transport
Bulk Transport: Endocytosis:
Pinocytosis: The membrane engulfs liquid and pinches a small part of itself to form a vesicle to bring inside the cell
Receptor- mediated endocytosis: The molecule outside the cell binds to a receptor on the outside of the membrane. The receptors move inward to form a pit with clathrin protein coated around. That piece of membrane is a vesicle that carries the molecule inside.
Phagocytosis: The membrane engulfs the food and pinches a small part of itself to form into a food vacuole to bring inside the cell
Pumps
Major electrogenic pump for animal cells
Sodium-potassium pump: pumps 3 sodium ions (positive) out and takes 2 potassium ions (positive) in
Main electrogenic pump for plants, fungi, and bacteria
Proton pump: transports hydrogen ions of positive charge to the extracellular side
Bulk Transport: Exocytosis: Molecules inside the vacuole is released outside of the cell and the vacuole becomes part of the membrane.
Requires energy (ATP)
Membrane Fluidity with Different Types of Lipid
The membrane is still fluid at lower temperature if it has a lot of phospholipids with unsaturated hydrocarbon chain (doubled bonds/kinks)
At low temperatures, if the membrane contains a lot of saturated hydrocarbon tails, it will become even less fluid. This is due to the phospholipids packing tightly.
Selective Permeability: only allows certain molecules to go through
Amphipathic: has both a hydrophobic and hydrophilic region
Membrane Fluidity With Cholesterol
The membrane's fluidity is reduced when cholesterol is in the membrane at moderate/warm temperature.
Cholesterol hinders solidification of phospholipids at low temperatures.