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Description
Flashcards by polina wright, updated more than 1 year ago
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Created by polina wright
about 5 years ago
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| Question | Answer |
| What kind of permeability does the plasma membrane have? | Selective |
| What substances does selective permeability allow to pass (vs) does not allow to pass | pass- small polar or non polar molecules (hydrocarbons, hydrophilic molecules) (co2 and o2) Cant Pass- ions and large polar molecules due to the hydrophobic core |
| What is the fluid and mosaic part of the fluid mosaic model? | fluid- membrane held together by weak interactions mosaic- phospholipids, proteins, and carbs |
| Functions of the plasma membrane | 1. physical isolation between internal cellular and external environments 2. regulation of nutrient and waste exchange 3. sensing changes in the environment or receiving communication signals from other parts of body 4. connecting to other cells and giving tissues a stable structure |
| what was the sandwich model, what was the problem, and who created it | sandwich model was a bilayer between 2 protein layers, problem was the protein layers (davson/danielli) |
| what did the freeze fracture method reveal | the structure of the membranes interior |
| Phospholipid bilayer | amphipatic hydrophilic head//hydrophobic tail |
| What does cholesterol do for membrane fluidity | resists changes by limiting fluidity at high temps and hinders close packing at low temps |
| what do phospholipids look like in low temps | have unsaturated tails, the kink prevents close packing |
| what are the types of membrane proteins | integral and peripheral |
| integral proteins | 1.embedded in membrane 2.determined by freeze fracture 3.transmembrane w/ hydrophilic heads or tails and hydrophobic middles |
| peripheral proteins | extracellular or cytoplasmic sides of membrane NOT embedded Held in place by cytoskeleton or ECM provides stronger framework |
| membrane proteins functions | 1.transport 2.enzymatic activity 3.signal transduction 4.cell-cell recognition 5.intercellular joining 6.attachment to cytoskeleton and extracellular matrix (ECM) |
| Carbohydrate functions | cell-cell recognition forming of tissues embryonic development |
| Example of carbs in plasma membrane | glycolipid and glycoprotein |
| Passive transport | No energy (atp) needed diffusion down concentration gradient high to low concentration |
| example of passive transport | hydrocarbons; co2, 02, h2o |
| define osmosis | diffusion of h2o |
| define tonicity | concentration of solute aka the solution |
| hypotonic what does it mean what will happen with water what will happen to cell | hypo-less (water will enter) and cell can burst |
| isotonic what does it mean what will happen to water what till happen to cell | same water stays same cell stays normal |
| hypertonic what does it mean what will happen to water what will happen to cell | more water will leave cell will shrivel as if you've had too much salt |
| facilitated diffusion | proteins help hydrophilic substances cross in 2 ways |
| What is way 1 of facilitated diffusion | provide hydrophilic channel |
| what is way 2 of facilitated diffusion | loosely bind/carry molecules across |
| example of facilitated diffusion | ions, polar molecules h20, glucose |
| define aquaporin | channel protein that allows passage of h20 |
| what type of protein is glucose transport protein | carrier protein |
| Active transport | requires energy (atp) proteins transport substances against concentration gradient low concentration to high concentration |
| examples of active transport | Na+//K+ pump H+ pump |
| what does H+ designate in (H+ pump) | proton |
| function of electrogenic pumps | generate voltage across membrane (2 types) |
| type 1 | Na+ // K+ pump pump Na+ out and K+ into cell Ex. nerve transmission |
| type 2 | proton pump push protons across membrane ex. mitochondria and atp production |
| contransport | membrane protein enables "downhill" diffusion of one solute to drive "uphill" transport of other |
| example of cotransport | sucrose H+ cotransporter (sugar-loading in plants) |
| compare and contrast passive vs active transport | passive- little/no energy...high to low concentration...down concentration gradient...ex. diffusion, osmosis, facilitated diffusion Active- requires energy...low to high concentration...against gradient...ex. pumps, endo and eco cytosis |
| osmoregulation | 1. controls solute and water balance 2. contractile vacuole- "bilge pump" forces out fresh water as it enters by osmosis 3. ex. paramecium caudatan- freshwater protist |
| bulk transport | a lot of stuff entering cell "transport of proteins, polysaccharides, and long molecules" |
| 2 types of bulk transport | endocytosis- take in macromolecules, form new vesicles exocytosis- vesicles fuse with cell membrane, and expel contents |
| types of endocytosis | 1.phagocytosis- cell eating 2. pinocytosis- cell drinking 3. receptor-mediated; ligands bind to specific receptors on cell surface |
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