Cell Transport
Cell Transport
-Cellular processes-anything that happens inside a cell to help it stay alive
-Equallibrium-
-Homeostasis- allows cells to change to changing conditions
CELL MEMBRANE IS KEY STRUCTURE THAT HELPS MAINTAIN HOMEOSTASIS
Phospholipid Bilayer
Aka the cell membrane- regulates what goes in and outside of the cell
-phosolipids make up cell membranes. They form a double layer and act as a barrier
-the head is polar making it hydrophilic or water-loving
-the fatty acid tails are non polar making then hydrophobic or water-hating
Cell Membrane Components
-Carrier proteins provide a path for large molecules to pass through the cell membrane
-CONCENTRATION GRADIENT: the amount of particles per space
-The difference in molecule numbers between two areas
EX: This is a high to low concentration
Cell Membrane Permeability
-Permiability means how easy something can go through it
-The cell membrane is semi permeable because it only lets certain things to go through
Review:
Cell Membrane: controls what goes in and out to maintain homeostasis
Determined by:
-the concentration gradient= amount of molecules
-cell membrane permeability= what can go through
Types Of Cellular Transport
-PASSIVE TRANSPORT: Requires NO energy
-ACTIVE TRANSPORT: Requires energy
Passive Transport (this section goes from here to osmosis)
-Moving molecules through a cell membrane without using energy
-molecules naturally go from high to low concentrations (following the concentration gradient)
-ALWAYS MOVES FROM HIGH TO LOW CONCENTRATION
Simple Diffusion/Justafusion
-Simply going through the cell membrane. HIGH TO LOW CONCENTRATION
-The molecules will move across the membrane until there is the same number on each side (equilibrium)
MOLECULES THAT USE DIFFUSION:
-Gases (oxygen, carbon dioxide)
-Lipid-soluble molecules (small fats)
-Steriod Hormones (estrogen and testosterone)
Facilitated Diffusion
-Going through the cell membrane using a protein.
-Facilitate =guide HIGH TO LOW like a gate
MOLECULES THAT USE FACILITATED DIFFUSION:
-Ions (charged molecules)
-Large Molecules (glucose)
-Polar Molecules (don't mix with hydrophobic tails of membrane)
Osmosis
-Moving WATER across a semi-permeable barrier (like the cell membrane)
OCEAN WATER: Hypertonicity:
-More molecules (solutes) outside the cell
-Water will move out of the cell
SALINE IV: Isotonic:
-Molecules (solutes) are the same in and out of the cell
-water moves in both directions equally
PURE WATER:Hypotonicity:
-less molecules (solutes) outside the cell.
-water will move into the cell
Active Transport
-Moving molecules across the cell membrane using energy (ATP)
ATP stands for adenosine triphosphate
-Molecules move LOW TO HIGH concentration (against the concentration gradient)
Sodium-Potassium Pump
The membrane protein uses ATP energy to:
-move 3 sodium ions (Na+) out of the cell
-Moce 2 potassium ions (K-) into the cell.
Bulk Transport (Active Transport Example)
Endocytosis:
-Cell takes in large molecules with its entire cell membrane
(-endo= In)
-Phagocytosis (“Cell Eating”)- (fay-go)- type of endocytosis
-Pinocytosis (“Cell Drinking)-type of endocytosis
Exocytosis:
-Cell releases a LARGE molecule using the cell membrane
-exo= exit
-used to get rid of waste and large molecules
Cell Transport Review:
Homeostasis
• Cell keeps conditions stable.
Transport
• Moving stuff in/out of the cell.
Passive Transport (no energy):
• Diffusion - molecules move high → low.
• Osmosis - water moves.
• Facilitated Diffusion-needs a helper protein
Tonicity (water balance):
• Hypertonic - water out, cell shrinks
• Hypotonic - water in, cell explodes
• Isotonic - balanced.
Active Transport (needs energy = ATP):
• Pump - moves molecules low → high.
• Endocytosis - big things in.
• Exocytosis - big things out.