Ions and minerals Flashcards
What is diffusion?
The net random movement of molecules from a region of high concentration to low concentration. Multicellular organisms evolve circulatory system to provide cells within their diffusion range.
What cellular structure behaves as a diffusion barrier?
Cell membrane
Which molecules can pass through the phospholipid bilayer?
Lipid soluble (Non-polar) molecules can diffuse passively with minimal resistance in comparison to water soluble (Polar molecules); phospholipid bilayer consist of hydrophobic tails repelling polar molecules.
What is osmosis?
Osmosis concerns the net movement of water across a partially permeable membrane from a region of high water potential (Hypotonic), to a region with low water potential (hypertonic).
Within isotonic solutions there is no net movement of water.
What is paracellular transport?
Molecules can pass the epithelial layer through tight junctions, and lateral intercellular spaces.
What is transcellular transport?
Transcellular transport: Transport of solutes through a cell.
What are the three membrane transport mechanisms?
Simple diffusion
Facilitated transport
Active transport
What are channel proteins?
Form aqueous pores enabling specific solute to pass cross the membrane
Faster method of transportation than carrier proteins
Channel proteins are linked with an internal hydrophilic surface in order to shield solutes from the hydrophobic fatty acid tails
What are carrier proteins?
Binds to solute and undergo conformational change to transport solute across the phospholipid bilayer into intracellular cytoplasmic space.
What are the three types of gated ion channels?
Voltage gated
Ligand gated
Mechanically gated
What is a uniporter?
A uniporter is an integral membrane protein that transports a single type of substrate species across a cell membrane
What are symporters?
Symporters are secondary active transporters that move two substances in the same direction. Example: Sodium-glucose symporter passively diffuses into the cell, resulting in the cooperative movement of glucose into the cell (Glucose has higher intracellular concentrations), as energy is supplied through passive sodium transport.
Secondary active
What is an anti-porter?
Sodium-hydrogen anti porter users energy from inward movement of sodium to move hydrogen ions extracellular (Used to maintain internal pH)
What are the two main examples of coupled transport?
Antiporters
Sympoters
What are the three main transport mechanisms?
Primary ative transporter
Secondary active transport
Facilitated transport
What is primary active transport?
Linked directly to cellular metabolism (Uses ATP to power the transporter of substrates)
What is secondary active transport?
Derives energy from the concentration gradient of another substance that is actively transported
What is facilitated transport?
Enhances the rate of a substance can flow its concentration gradient, there is a tendency to equilibrate the substance across membrane
What are the two main examples of secondary active co transporters?
SGLT-1 co transporter (Monosaccaride absorption)
HCO3/Cl- counter transporter
How are glucose and galactose molecules absorbed within enterocytes?
Secondary active transport, through SGLT-1 on enterocyte apical membrane and electrochemical gradient
What is SGLT-1?
Has the ability to transport glucose against concentration gradient, therefore effective when extracellular luminal concentrations are comparatively less than that in enterocytes
What type of transport enables fructose absorption into enterocytes?
Facilitated diffusion
Which carrier protein is involved in the fructose absorption on the apical membrane of enterocytes?
GLUT-5 glucose co-transporters
Which transporters are involved in the exist of carbohydrates from enterocytes?
GLUT-2
