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81 Cards in this Set
- Front
- Back
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All cells and organelles are surrounded by what?
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Membranes
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Membranes function to...
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Separate compartments
Control molecular traffic in and out |
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Membranes are selectively permeable. What does that mean?
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Some substances can cross easily and others cannot get across.
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What is the term when some substances can cross easily and others cannot get across?
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Selectively permeable.
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Which ends of the phospholipid bilayer are attracted to each other?
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Fatty acid ends
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What composes the two parts of the membrane?
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Phospholipid bilayer
Proteins embedded in the phospholipid bilayer |
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What must a protein have to remain embedded in the phospholipid bilayer?
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A hydrophobic region
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What would happen if a protein did not have a hydrophobic area?
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It would pop out of the phospholipid bilayer.
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The membrane is _____.
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Fluid
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Where are the proteins located in the phospholipid bilayer?
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The "float" freely in the lipids
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Which directions can the phospholipids move within the bilayer?
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In all directions.
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How often do the phospholipids make lateral movements within the bilayer?
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~10^7 times per second
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How often do the phospholipids make vertical movements within the bilayer?
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~once per month
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The fluidity of the membrane is impacted by what?
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Level of saturation of the fatty acid tails
Temperature |
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Which fatty acid makes the membrane less fluid?
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Saturated fatty acids
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Which fatty acid makes the membrane more fluid?
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Unsaturated fatty acids
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What does colder temperatures do to the fluidity of a membrane?
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Makes it less fluid
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What does warmer temperatures do to the fluidity of a membrane?
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Makes it more fluid
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A membrane that is too fluid or hot is what?
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Too leaky
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What can happen if a membrane is to rigid or cold?
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Damage can occur
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Hydrocarbon tails with kinks causes what kind of membrane?
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Fluid membrane
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Hydrocarbon tails without kinks causes what kind of membrane?
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Viscous membrane
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What can help keep membranes fluid by "breaking up" the lipids, particularly at low temperatures.
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The steroid cholesterol
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How can cholesterol help a membrane?
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by "breaking up" the lipids and helping keep the membrane fluid.
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The proteins in the membrane are either ____ or ____.
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peripheral or integral
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What is a peripheral protein?
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A protein anchored to a phospholipid and moves with it in one layer
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What is an integral protein?
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It can go from one side of the membrane to the other.
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What type of protein cannot cross the bilayer?
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A peripheral protein
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Which protein goes from one side of the membrane to the other?
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An integral protein
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What are the various functions of membrane proteins?
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Transporters
Enzymes Cell surface receptors Cell surface identity markers Cell-to-cell adhesion proteins Attachments to the cytoskeleton |
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Where are membrane proteins and lipids synthesized?
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In the ER and Golgi
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What is diffusion?
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The movement of molecules from a high concentration to a low concentration.
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What type of molecules can diffuse directly across the lipid bilayer?
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Apolar molecules like O2, CO2, hydrocarbons
Small, uncharged polar molecules H2O |
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How do large polar molecules and ions get across the membrane?
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They use transport proteins
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What type of molecules must use transport proteins to cross the membrane?
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Large polar molecules and ions
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What type of transport requires no energy?
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Passive
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What is the passive transport of water across a membrane?
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Osmosis
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Water will always travel to where there is more _____ and less ____.
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solutes, water
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Osmosis is always _____.
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Diffusion
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The direction of osmosis is determined only by a difference in total ____ concentration.
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Solute
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What is happening when two solutions have equal solutes?
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There is still movement but no net osmosis.
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Two solutions on either side of a membrane can have three possible names in regards to osmosis, what are they and what are their characteristics?
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Hypertonic- solution has more solutes
Hypotonic- solution has less solutes Isotonic- solution has the same number of solutes as the solution on the other side of the membrane |
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What does hypertonic mean?
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The solution has more solutes.
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What does hypotonic mean?
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The solution has less solutes.
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What does isotonic mean?
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The solution has the same number of solutes as the solution on the other side of the membrane.
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What type of solution has more solutes?
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Hypertonic
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What type of solution has less solutes?
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Hypotonic
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What type of solution has the same number of solutes as the solution on the other side of the membrane?
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Isotonic
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What is the best type of solution to kill a plant cell and why?
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Hypertonic, because water move from high concentration in the cell to lower concentration causing the cell body to shrink away from the cell wall.
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What is the best type of solution to kill a animal cell and why?
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Hypotonic, because water will move from high concentration outside the cell to a lower concentration in the cell causing it to swell and burst.
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For a molecule to cross the membrane, it has to either:
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Directly cross through the lipids
Cross through a protein |
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What kind of transport can happen with or without a protein?
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Passive transport
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In passive transport, molecules travel from ____ to ____ concentration.
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High to low
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In passive transportation, the molecule moves three different ways, what are they?
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Spontaneously via Simple diffusion
Channel protein mediated Carrier protein mediated. |
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What kind of transport requires a protein to facilitate movement?
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Active transport
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What kind of transport can go against the concentration gradient?
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Active transport
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What are the two types of facilitated diffusion in passive transport?
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Channel
Carrier |
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Which proteins allow fast transport through the membrane?
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Channel
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What is one example of a channel protein that allows water to move in and out of the cell when they are open.
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Aquaporins
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When going from a low concentration gradient to a high concentration gradient, ____ transport is needed.
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Active
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What causes a carrier protein to change shape?
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When the specific molecule binds to the protein, it changes shape and allows the molecule through.
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What energy is usually supplied for active transport?
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ATP
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What does a proton pump do?
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It moves protons outside of the cell against their concentration gradient.
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The proton pump moves protons from the _____ to the _____.
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inside to the outside
cytoplasm to the extracellular fluid |
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What are the three type of carrier proteins in active transport.
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Uniporters
Symporters Antiporters |
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What do uniporters do?
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Move one molecule at a time
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What do symporters do?
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Move two molecules in the same direction
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What do antiporters do?
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Move two molecules in opposite directions
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What happens in the Sodium-Potasium pump.
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It uses an antiporter to move 3 Na+ out of the cell and 2 K+ into the cell.
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The sodium potasium pump moves 2 K+ ____ the cell and 3 Na+ ____ the cell.
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into, out of
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The sodium potasium pump moves 3 Na+ ____ the cell and 2 K+ ____ the cell.
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out of, into
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Bulk transport of substances is accomplished by _____ and ____. What does each do.
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Endocytosis- movement of substances into the cell
Exocytosis- movement of substances out of the cell |
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What are the three types of endocytosis?
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Phagocytosis
Pinocytosis Receptor-mediated endocytosis |
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What is phagocytosis?
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When the cell takes in particular matter.
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What is pinocytosis?
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When the cell takes in only fluid
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What is receptor-mediated endocytosis?
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Specific molecules are taken in after they bind to a receptor
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What type of movement occurs when the cell takes in particular matter?
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Phagocytosis
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What type of movement occurs when the cell takes in only fluid?
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Pinocytosis
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What type of movement occurs when specific molecules are taken in after they bind to a receptor?
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Receptor-mediated endocytosis
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In what type of solution is a plant cell the happiest?
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Hypotonic
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In what type of solution is an animal cell the happiest?
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Isotonic
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