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31 Cards in this Set
- Front
- Back
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What is a cell membrane? |
- Double lipid molecule layer - Phospholipid bilayer - Fluid Mosaic |
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What is the use of sugars on the outside of the surface? |
To identify the type of cell. - glycoprotein (recognition protein) |
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What IS hydrophilic? |
Dissolves in water |
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What is hydrophobic? |
Does not dissolve in water |
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Define phospholipid bilayer |
Non-polar layer which makes it difficult for water soluble materials to pass through. |
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Functions of protein in the cell membrane? |
- Channel protein - Carrier protein - Cell recognition protein - Receptor protein - enzymatic protein |
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Define channel protein. |
Allows particular molecule or ion to cross plasma membrane freely. |
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Define carrier protein. |
Selectively interacts with specific molecule or ion so that it can can cross the plasma membrane. |
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Define Cell recognition protein. |
Recognize and identify molecules or ions and the type of cell. |
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Define receptor protein. |
Shaped in a way that a specific molecule can bind to it. |
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Define enzymatic protein. |
Catalyzes a specific reaction. |
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What is cystic fibrosis ? |
A inherited disorder caused by a faulty chloride channel; thick mucus collects and airways and in pancreatic and liver ducts |
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How do molecules cross the plasma membrane? |
- Diffusion - Osmosis - Active transport - Facilitated transport - Endocytosis - Exocytosis |
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Define diffusion. |
Movement of molecules from a higher to a lower concentration until they are distributed equally. |
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Define osmosis |
The diffusion of water into and out of cells moving from high concentration to low concentration. |
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What is the rate of diffusion affected by? |
- size and shape of molecules - temperature - concentration gradient ( high when there is a large difference in concentration between two molecules) - medium (gas = fast, liquid = slow) |
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What is a solute? |
The particles dissolved in the solvent. |
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Define hypertonic. |
Solutions that have a high concentration of solute (= low water) = cell shrinks ( crenation) |
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Define hypotonic |
Solutions that have a lower concentration of solute (= high water) = cell shrinks |
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Define isotonic or isosmotic. |
Two solutions separated by the membrane are of equal water and solute concentration. Water moves in and out at the same rate. |
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Define active transport |
Protein carriers use energy to move molecules from low concentration to high. (Eg. Sugar is absorbed by the gut by the cells lining the digestive track) |
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Define Facilitated transport |
Passage of molecules from high concentration to low concentration across the cell membrane even though they are lipid insoluble (helped across by proteins carriers) (eg. Glucose and amino acids) |
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Define Endocytosis. |
- Cells suck in fluids or large particles - requires energy and the formation of vacuoles |
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What are two types of endocytosis? |
- Pinocytosis - "cell drinking" (molecules = disaccharide) - phagocytosis - "cell eating" (when material is large = bacteria/ worn out red blood cell) |
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Define exocytosis |
- reverse of endocytosis - A vesicle fuses with the cell membrane and discharges its content (waste product) |
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What is dynamic equilibrium |
Leaving and entering the cell at the same rate |
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What are two major problems if a large organism is made of one large cell? |
1. Diffusion will not work well as it works very well over short distances and is very slow for long distances.
2. More chemical reactions occur as volume increases more rapidly. (More food and oxygen needed and more waste is made). Surface area can't keep up |
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Define turgor pressure. |
Internal pressure that adds to to the strength of a cell and builds up when water moves by osmosis in the cell. (Plants) |
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Define plasmolysis. |
Shrinking of the cell due to loss of water. (Plants) |
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Define lysis. |
Water enters the cell which may burst due to osmotic pressure in a hypotonic environment. (Animals) |
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Define crenation |
Cell shrivels up and dies in a hypertonic environment because water leaves. (Animals) |
