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Transport Material
Bio 2 Lecture 4
| Question | Answer |
|---|---|
| What is passive transport? How does the substance move? | Passive transport is a substance moving through to plasma membrane. The substance moves down the concentration gradient, meaning from High to Low. No energy required |
| What is active transport? How does the substance move? | Active transport is a substance moving through the plasma membrane. The substance goes up the concentration gradient (so moves against concentration gradient), meaning from Low to High. It requires a carrier protein and energy. |
| What are the 3 types of passive transport? | Passive diffusion, Facilitated diffusion and osmosis |
| What are the specificities of passive diffusion? Energy? Concentration gradient? | Substances move via simple diffusion (H--»L), though the lipid bilayer (aka PM), no energy is required, and only small non polar molecules can go past the lipid bilayer easily |
| Movement is a response to what? | To a concentration gradient, passive would be H--»L and active would be L--»H |
| Is a carrier protein required in passive diffusion? | No, small non-polar molecules go through the lipd bilayer easily.However, other bigger molecules need help. |
| What are the specificities of facilitated diffusion? Energy? Concentration gradient? | Facilitated diffusion is passive transport (so H to L), but the substances move through a pore/carrier protein. It still requires no energy. |
| What are the 2 transport proteins in facilitated diffusion? | There's channel/pore protein and there's carrier proteins. |
| What are Channel/pore proteins? | They permit only specific solutes to pass through, like water, hydrophilic solutes and some ions |
| What are protein carriers? | They help transport through PM, they change their shape to bind to a specific molecule to move it accross the PM like glucose or sodium (Na+) |
| What is osmosis? | It's the movement of water accross the selectively permeable PM, from High to Low concentration of WATER. |
| In osmosis, water moves through what? Why? | Through aquaporin channels in response to the solute conditions on 2 sides of a membrane |
| Water moves in response to.. | a solute concentration |
| In what direction does water move? | Towards the region containing high solutes |
| What is tonicity related to? | To solute concentrations |
| How to evaluate whether something is hypertonic, hypotonic or isotonic? | Hypertonic solutions: More solutes and less solvents Hypotonic solutions: Less solutes and more solvent Isotonic: Equal solute and solvent |
| Situation: You have low salt outside the cell and water is high, so where does the water move? | It moves inside the cell where the salt is high and the water is low |
| What is hypotonic and hypertonic? | Hypo=High water Hyper=Low water |
| Situation: If [solute] is high outside the cell, the solution outside the cell is [..]tonic compared to inside. What about the inside of the cell? | Hypertonic :D, the outside is hypotonic :_ ) |
| What is the process of osmoregulation? | Maintaining salt and water balance accross membranes within the body! |
| Explain the steps of osmoregulation | 1.Extrusion: water ejected from cell through contractile vacuoles (Paramecium, amoeba) 2.Isosmotic regulation: involves keeping cells isotonic with their environment. Salts are balanced (Some salt-water fish) 3. Plant cells use tugor pressure (next Q:) |
| What is tugor pressure (osmoregulation)? | Plant cells use turgor pressure to push the cell membrane against the cell wall and keep the cell rigid, thus blocking entry of too much water. |
| What impacts the passive transport rate? | Environmental factors like temperature, solute concentration and saturation |
| If you increase the temperature, the diffusion rate.. | increases (goes faster) |
| Does active transport need energy? What are the other specificities of this kind of transport? | It requires ATP energy. Also, it's specific and can saturate. It needs carrier proteins |
| What are the types of cotransport (carriers)in active transport? | 1) Uniporters: Move a single type of protein 2) Symporters: Move 2 different molecules in the same direction 3) Antiporters: Move 2 different molecules in opposite direction |
| What is the Sodium-Potassium (Na+, K+) pump? | It's the use of an antiporter to move 3 Na+ out of the cell and 2 K+ into the cell |
| What is used to change the shape of the carrier protein in the Sodium-Potassium (Na+, K+) pump? | ATP energy (aka transferring a phosphate group directly to a carrier protein) |
| In the Sodium-Potassium (Na+, K+) pump, how is the affinity changed? | The terminal phosphate group will bind to the protein, which changes the shape of the protein, which will change the affinity (changes the preference) to either K+ or Na+ |
| What are the steps of the sodium-potassium pump? (Refer to slides for more detail 30) | 1) Carrier in membrane binds to sodium in the cell 2)ATP phosphorylates binds with bound Na+ 3)phosphorylation causes a shape change, which reduces affinity with Na+ (Na diffuses out) 4) New shape has affinity with K+. K+ outside cell binds 5) Next Q |
| What are the steps of the sodium-potassium pump? suite step 5 and 6 | 5)ATP phosphorylates detaches (dephosphorylation of protein) 6)Dephosphorylation causes another shape change (back to shape 1), K+ is no longer the affinity so it diffuses inside the cell, and the cycle repeats |
| What is a cotransport? How does it work? BTW [gradient]= concentration gradient! | Coupled transport of chemical substance accross a cell membrane. Energy released from the “flow” of a molecule moving down a gradient, can provide energy to actively transport a dif. molecule, which is moving through the membrane against a [gradient.] |
| Explain the Glucose-Na+ symporter cotransport | As they go in the same direction, glucose uses the energy from Na+ moving IN the cell by diffusion going down a concentration gradient (H to L). Glucose moves accross the membrane against a concentration gradient |
| Which one is antiporter and which is symporter: Na+/K+ pump and glucose/Na+ pump? | Na+/K+ pump is antiporter bc 2 molecules are transported in opposite direction. Glucose/Na+ pump is symporter bc 2 molecules same direction. |
| What is bulk transport? | It's when larger substances or large packages of small molecules are transported through the cell membrane |
| How can bulk transport be achieved? | By endocytosis (Movement of bulk substances into the cell) and exocytosis (Movement of bulk materials out of the cell) |
| When does endocytosis occur? | When the plasma membrane envelops food particles and/or liquids to bring them into the cell. |
| What are the 3 sub-division of endocytosis? | 1) Phagocytosis (cell takes in particulated matter) 2) Pinocytosis (cell takes in fluid only) 3) Receptor-mediated endocytosis (specific molecules are taken in after they bind to a receptor) |
| When does exocytosis occur? How does it happen? | When material is discharged from the cell (such as waste). Vesicles in the cytoplasm fuse with the cell membrane and release their contents to the exterior of the cell |
| What are the steps to the exocytosis process? | 1) Vesicle approaches PM 2) Vesicle fuses with PM 3) Content is released |
| How is exocytosis used in plants and animals? | Plants: Export cell wall material Animals: Secretes hormones, neurostransmitters, digestive enzymes |
| How many types of transports is there en gros? | Passive, active and bulk transport (do concept map!) |
| Identidy three mechanisms used to regulate water in living organisms. | Extrusion (Protists), isosmotic regulation (fish) and turgor pressure (plants) |
Created by:
Malayka
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