lecture 8 Flashcards
What is Passive Transport, and what requirements does it have to get something into or out of a cell? Does it take energy?
Passive transport: diffusion across a biological membrane. Movement is down its concentration gradient.
does not require the cell to expend any energy and involves a substance diffusing down its concentration gradient across a membrane.
what is the difference between Passive Transport and Osmosis?
Passive Transport start with different solutes on opposite sides of a lipid bilayer and both molecules move freely across its bilayer. The solutes diffuse across the membrane until equilibrium is established. Solutes will continue to move back and forth across the membrane at equal rates
Osmosis is the diffusion of the solvent, not the solute. It passes through a selectively permeable membrane.
Be familiar with the mechanism of the GLUT-1 protein
A carrier protein, part of facilitated diffusion.
Glucose transporter.
Opens from different directions depending on how much glucose there is. Open top if there is more glucose outside the cell, open bottom if more glucose inside cell.
Glut 1 protein is very specific to glucose- The R group of the proteins have oxygens and amino groups (spaced just perfectly for glucose) that will hydrogen bond to glucose’s hydroxyl groups.
two main types of Channel proteins
Channel Proteins: free pass through protein
Carrier Proteins: open and close gates
Active Transport – how does active transport differ from Passive transport, in conditions and energy requirements?
Active transport involves IONS and large molecules
requires energy- moves molecules against their gradient.
chemical gradient (difference in solute)
electrochemical too (difference in charges).
electrochem gradients don’t just happen, they are created.
sodium potassium pump
High sodium outside of cell and low inside of cell
Low potassium outside cell and high inside is high
3 Sodium ions from inside the cell move into the carrier protein (pump). Pump is activated when phosphate groups enter. As three sodium leaves, two potassium goes in
when ATP turns into ADP. ATP drops off one of its phosphates groups to pump
symport and hat type of transport is NA+/ glucose
Symport: A protein that transports two substances in the SAME direction
Na+/glucose symport is secondary active transport aka cotransport. See below
Where does the energy come from to power Secondary Active Transport?
usees stored energy from electrochemical gradient of one molecules (from primary transportation) to drive the active transport of another molecule.
Is Na+ the only ion that can be used for secondary active transport?
no, H+ preferred in plants
What sorts of life forms use these different ions for energy gradients?
How does that support the idea that Mitochondria and Chloroplasts are endosymbionts?
Under conditions of High Glucose Concentration in the gut (right after a meal)
Under conditions of Low Glucose Concentration in the gut (between meals)
