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30 Cards in this Set
- Front
- Back
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Define osmosis.
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the net movement of water molecules from a dilute solution (high water potential) to a more concentrated solution (low water potential) across a partially permeable memebrane
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Define diffusion.
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the net movement of particles from an area of high concentration to an area of low concentration
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What is a turgid cell?
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A cell that contains as much water as possible.
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What happens to a plant cell that loses too much water?
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it pulls away from the cell wall and is plasmolysed
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What happens to an animal cell that loses too much water?
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it shrivels and is crenated
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By what two processes can substances enter and leave the cell?
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Endocytosis and exocytosis
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Define hydrophilic.
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Attracted to water
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Define hydrophobic.
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Repulsion from water
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Describe the structure of a phospholipid.
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hydrophilic polar head and a non-polar hydrophobic tail
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Describe the structure of a phospholipid bilayer.
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presents the hydrophilic heads to water based solutions either side
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What does the fluid mosaic model refer to? |
-the ability of phospholipids and proteins to move around relative to each other -the various shapes and sizes of the molecules in a membrane |
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What crosses the entire bilayer?
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Transmembrane or intrinsic proteins
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True or false. Carrier and channel proteins are intrinsic. |
True
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How do channel proteins work?
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They form a passageway/pore
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How do carrier proteins work?
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they change shape to move substances across the membrane
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What is an antigen?
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a foreign body that stimulates an immune response and the production of antibodies
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Give three ways in which glycoproteins are useful: |
-stabilizing the membrane -cell signaling -form surface antigens (along with glycolipids) |
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What is the function of cholesterol?
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maintains fluidity in the plasma membrane
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How does an increase in temperature effect the plasma membrane?
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increases fluidity and makes it more permeable
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What happens if the plasma membrane reaches 40 degrees C?
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proteins denature, causing irreversible disruption to the membrane
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Define cell signaling.
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the release of chemicals from one cell and the detection of the chemical by other cells that have the correct receptors leading to a change in the cell as a result
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Complete the sentence. Messenger molecules must be a ________________ to their correct ________. |
complementary shape receptor |
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What is a target cell? |
A cell that responds to a particular message
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What three things can messengers cause?
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-release of second messenger inside cell -opening/closing of a protein channel -activation of an enzyme |
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Complete the sentence: Drugs such as __________ interfere with __________. |
antihistamine cell signaling |
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What is facilitated diffusion?
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using channel proteins or carrier proteins to allow polar molecules, ion or larger molecules to diffuse across the plasma membrane
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Which is the odd one out? -Diffusion -Osmosis -Active Transport -Facilitated Diffusion |
Active transport it requires energy as it goes against the concentration gradient |
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What is active transport?
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using carrier proteins to transport particles across the plasma membrane against their concentration gradient using energy for ATP
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Give two examples of endocytosis.
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Phagocytosis and pinocytosis
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Define invagination.
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folding inwards to form a pocket
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