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85 Cards in this Set
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Plasma Membrane |
- Common to all Cells - Separates the internal cytoplasm from the external environment of the cell - Selectively permeable - Not everything crosses - Allows sometimes incompatible chemical reactions to occur simultaneously - Fluid mosaic model accounts for the structure |
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Phospholipid Bilayer |
- External and cytoplasmic surfaces lined with hydrophilic polar heads - Non-polar, hydrophobic fatty acid tails sandwiched in between |
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- Lipid Component: Phospholipid Bilayer - Protein Molecules: Peripheral or Integral - Cholesterol: Also a lipid amongst the proteins in the phospholipid bilayer |
3 Components of the Plasma Membrane |
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Peripheral Proteins |
Proteins Found in the inner membrane surface |
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Integral proteins |
Proteins that are partially or wholly embedded (Transmembrane) in the membrane |
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Cholesterol (In Plasma Membrane) |
Lipid that affects fluidity in plasma membrane |
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Carbohydrate Chains |
- Makes the membrane assymmetrical - Exist only on the outside of the plasma membrane - Contribute to cell's "fingerprint", play a role in cellular identification - Thus important in tissue transplantation and blood transfusions - One with proteins: Glycoproteins - One with Lipids: Glycolipids |
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Glycoproteins |
Proteins with attached carbohydrate chains |
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Glycolipids |
Lipids with attached carbohydrate chains |
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Channel Proteins Carrier Proteins Cell Recognition Proteins Junction Proteins Enzymatic Proteins Receptor Proteins CCCJER |
Types of Membrane Proteins (6) |
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Channel Proteins |
- Allow passage of molecules through membrane via a channel in the protein - Allows a particular molecule or ion to cross the plasma membrane freely Ex: Cystic fibrosis has faulty chloride channels |
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Carrier Proteins |
- Combine with the substance to be transported - Assist passage of ions and polar molecules through membrane - Selectively interacts with a specific molecule or ion so that it can cross the plasma membrane Ex: Inability of some persons to use energy for sodium-potassium transport has been suggested as the cause of their obesity |
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Cell Recognition Proteins |
- Glycoproteins - Help the body recognize foreign substances Ex: MHC (major histocompatibility) glycoproteins are different for each protein, so organ transplants are difficult to achieve, attacked by white blood cells responsible for immunity |
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Receptor Proteins |
- Bind with specific molecules - Allow a cell to respond to signals from other cells Ex: Pygmies are short, not because they do not produce enough growth hormone, but because their growth hormone receptors on plasma membrane are faulty and cannot interact with growth hormone |
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Enzymatic Proteins |
- Carry out metabolic reactions directly - Catalyzes a specific reaction Ex: Adenylate cyclase is involved in ATP metabolism Ex: Cholera bacteria release a toxin that interferes with the proper functioning of adenylate cyclase; sodium and water leave intestinal cells, and the individual may die from severe diarrhea |
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Junction Proteins |
- Membrane proteins that attach adjacent cells Ex: Tight junctions join cells so that tissue can fulfill function; without this cooperation between cells, an animal embryo would have no nervous system |
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Cystic Fibrosis |
An inherited disorder, is caused by a faulty chloride channel protein, a thick mucus collects in airways and in pancreatic and liver ducts |
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Carrier Protein Deficiency |
Inability of some persons to use energy for sodium potassium (Na+-K+) transport has been suggested as a cause of their obesity. Example of a deficiency in what kind of protein? |
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Cell Recognition Protein |
The MHC (major incompatibility complex) glycoproteins are different for each person, so organ transplants are difficult to achieve. Cells with foreign MHC glycoproteins are attacked by white blood cells responsible for immunity. Example of a deficiency in what kind of protein? |
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Receptor Protein |
Pygmies are short, not because they do not produce enough growth hormone, but because their plasma membrane growth hormone receptors are faulty and cannot interact with growth hormone. Example of a deficiency in what kind of protein? |
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Enzymatic Protein |
Example of a deficiency in what kind of protein? The membrane protein ADENYLATE CYCLASE is involved in ATP metabolism. Cholera bacteria release a toxin that interferes with the proper functioning of adenylate cyclase; sodium (Na+) and water leave intestinal cells, and the individual may die from severe diarrhea. |
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Junction Proteins |
Tight junctions join cells so that a tissue can fulfill a function, as when a tissue pinches off the neural tube during development. Without this cooperation between cells, an animal embryo would have no nervous system. Example of what kind of protein? |
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Signaling Molecules |
- Serve as chemical messengers, allowing cells to communicate with one another - Cell Receptors bind to specific ones, causing cascade of events that elicits a cellular response |
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Signal Transduction Pathway |
This is an example of what? Pancreas released the hormone insulin, which transports to blood vessels in the liver, this causes the storage of glucose as glycogen. |
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Diabetes |
Failure to store glucose as glycogen causes a medical condition called _______ |
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Cell Signaling |
1. Receptor: Binds to a signaling molecule, becomes activated and initiates a transduction pathway 2. Transduction Pathway: Series of relay proteins that ends when a protein is activated 3. Response: Targeted protein(s) bring about a cellular response This process describes what? |
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Structural protein Cytoplasm |
When the cellular response is an Altered shape or movement of cell, what type is the targeted protein? This occurs where? |
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Enzyme Protein Cytoplasm |
When the cellular response is anAltered metabolism or cellular function, what type is the targeted protein? This occurs in the? |
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Gene Regulatory Protein Nucleus |
When the cellular response is Altered gene expression and the types and amount of proteins produced, what type is the targeted protein? This occurs in the? |
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Selectively permeable (Plasma Membrane) |
- Allows some substances to move across the membrane - Inhibits passage of other molecules such as polar molecules - Small, non-charged molecules (CO2, O2, glycerol, alcohol) freely cross the membrane by passing through the phospholipid bilayer by following their concentration gradient |
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Aquaporins |
Specialized proteins that speed up water transport across the membrane |
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Bulk Transport |
- Way large particles enter or exit the cell - Macromolecules are transported into or out of the cell by vesicles - 2 Types |
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Diffusion (Passive Transport) Facilitated Diffusion (Passive Transport) Osmosis (Passive Transport) Na+/K+ Pump (Active Transport) Endocytosis (Active Transport) Exocytosis (Active Transport) |
Passage of Molecules into and out of Cell (6) |
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Solution |
Consists of solvent (liquid) and solute (dissolved solid) |
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Diffusion |
- Net movement of molecules down concentration gradient - Molecules move both ways but net movement is from high to low concentration - Equilibrium is when net movement stops, concentration is uniform - Temperature, pressure, electrical currents and molecular size affect the rate of this |
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Equilibrium |
- When net movement stops - Solute concentration is uniform, no gradient |
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Temperature Pressure Electrical currents Molecular size |
Factors that influence the rate of diffusion (4) |
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Osmosis |
- Focuses on solvent (water) movement rather than solute - Diffusion of water across selectively permeable membrane - Water can diffuse both way across membrane but solute cannot - Net movement of water is toward low water (high solute) concentration |
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Osmotic Pressure |
Pressure that develops due to osmosis |
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Isotonic Solutions |
- Solute and water concentrations are equal on both sides of cellular membrane - No net gain or loss of water by cell |
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Hypotonic Solutions |
- Concentration of solute in the solution is lower than inside the cell - Cells placed in this solution will swell, causing turgor pressure in plants and lysis in animal cells |
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Contractile vacuole |
Protozoans living in fresh water environments have this organelle to rid themselves of excess water in hypotonic solution |
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Hypertonic Solution |
- Concentration of solute is higher in the solution than inside the cell - Cells placed in this solution will shrink, crenation in animal cells, plasmolysis in plant cells |
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Crenation |
- The shrinking of red blood cells (animal cells) when placed in hypertonic solution, anything higher than 0.9% sodium chloride |
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Plasmolysis |
- In plant cells, plasma membrane pulls away from cell wall and cytoplasm shrinks - Dead plants along salted roadway - died because exposed to hypertonic solution |
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- Hypotonic -Isotonic -Hypertonic |
In what solution are plants cells turgid (normal)? Flaccid? Plasmolyzed? |
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Facilitated Transport |
- Movement of molecules cannot pass directly through the membrane lipids (Glucose and amino acids) - Must combine with carrier proteins to move across - Follows concentration gradient - No energy required |
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Active Transport |
-Movement of molecules against their concentration gradient from low to high - Facilitated by specific carrier proteins - Requires expenditure energy in the form of ATP - Ex: Na.K Pump (Na+3 out, K+2 in) |
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Exocytosis |
Vesicles fuse with plasma membrane and secrete contents/particle outside the membrane |
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Endocytosis Phagocytosis Pinocytosis Receptor-Mediated |
Cells engulfs substances into a pouch, which becomes a vesicle to move particle to inside the plasma membrane - 3 Types? |
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Phagocytosis |
- Large, solid material is taken in by endocytosis Ex: Human white blood cells can engulf debris or viruses Ex: Food vacuole formed by pseudopodium |
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Pinocytosis |
Protein coated vesicles form around a liquid or very small particles in "cell drinking" |
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Receptor Mediated Endocytosis |
Specific form of pinocytosis using membrane receptor proteins and a coated pit Ex: Hypercholesterolemia is a diease when cholesterol transport is defective |
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Extracellular Matrix |
Meshwork of proteins and polysaccharides in close with the cell that produced them |
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Solvent (Liquid) Solute (Dissolved Solid |
Solution consists of these 2 things |
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Collagen (Resists stretching) Elastin (Provides resilience to the Extracellular matrix) Fibronectin (Adhesive protein which binds to) Integrin (Play role in cell signaling) Proteoglycans CEFIP |
Extracellular Matrix Components (5) |
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Collagen |
Protein component of the extracellular matrix that resists stretching
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Elastin |
Protein component of the extracellular matrix that provides resilience and helps it maintain its shape |
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Fibronectin |
Component of the extracellular matrix that is an adhesive protein which binds to Integrins |
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Proteoglycans |
- Proteins that attach to a long centrally polysaccharide which resists compression of the extracellular matrix - Assist cell signaling by regulating passage of material through the Extracellular matrix to the plasma membrane - Guide cell migration |
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Integrin |
Protein component of the extracellular matrix that plays a role in cell signaling
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Adhesion Junctions - Desmosomes, Tight Junctions |
- Intercellular filaments connect cells to one another - Give 2 types |
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Desmosomes |
- Adhesion junction: Intercellular filaments connect cells to one another - Have internal cytoplasmic plaques |
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Tight Junctions |
- Adhesion junction: Intercellular filaments connect cells to one another - Form impermeable barriers between cells |
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Gap Junction |
- Plasma membrane channels join adjacent cells to one another - allowing communication - Esp. important in heart muscle and smooth muscles |
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Plant cells |
- Freely permeable cell wall with cellulose as main component - Plasmodesmeta penetrate the cell wall and connect the cytoplasm of adjacent cells to one another, allowing passage of material between cells What type of cell? |
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Plasmodesmata |
- Penetrates the cell wall and connects the cytoplasm of adjacent cells to one another - Each contains a strand of cytoplasm - Allow passage of material between cells - Sort of like integral proteins of the plant cell because allows material passage and "talking" receptor functions |
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Secondary cell wall |
- Cells in woody plants have a secondary one containing lignin and more cellulose fibers than the primary cell wall - This is called? |
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CO2 O2 GLYCEROL ALCOHOL |
Small, non charged molecules that can diffuse freely through the cell membrane by their concentration gradient. (4 types) |
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Glucose and amino acids |
Examples of molecules that pass through the cell membrane by facilitated diffusion (2) |
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Lignin and more cellulose fibers than the primary cell wall |
The secondary cell wall of woody plants contain what that is different from the primary cell wall? (2) |
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- Assists in the movement of substances across the plasma membrane. - Prevents the loss of water when cells are placed in a hypertonic solution - Has numerous functions that affect the shape and activities of the cell that produced it - Contains the junctions that sometimes occur between cells. |
The extracellular matrix does what? (4)
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The intermolecular interactions are much weaker than saturated molecules. As a result, the melting points are much lower for unsaturated fatty acids
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Winter wheat is planted in the early fall, grows over the winter when the weather is colder, and is harvested in the spring. As the temperature drops, the makeup of the plasma membrane of winter wheat changes.
Unsaturated fatty acids replace saturated fatty acids in the phospholipids of the membrane. Why is this a suitable adaptation? |
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When the chloride ions leave these cells, water follows, thinning the mucus. With less chloride leaving the cells, less water leaves, and mucus becomes thick and sticky. The mucus can no longer move freely through the passageways, and they become clogged. |
As mentioned, cystic fibrosis is a genetic disorder caused by a defective membrane transport protein. The defective protein closes chloride channels in membranes, preventing chloride from being exported out of cells. This results in the development of a thick mucus on the outer surfaces of cells. This mucus clogs the ducts that carry digestive enzymes from the pancreas to the small intestine, clogs the airways in the lungs, and promotes lung infections. Why do you think the defective protein results in a thick, sticky mucus outside the cells, instead of a loose, fluid covering? |
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Protection Signal Reception Adhesion Cell to Cell Recognition |
Functions of the glycocalyx (type of glycoprotein) (4) |
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Regulated secretion |
Specific needs of the body triggering vesicles to fuse with the plasma membrane is called: |
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Plasma membrane |
Vesicles formed by the golgi apparatus usually go to the? |
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D) All of the above |
A major chemical that regulates the fluidity of animal cell membranes by stiffening the membrane at higher temperatures and preventing the membrane from freezing at lower temperature is A) cholesterol B) lipid in nature C) steroid D) all of the above |
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A) Channel proteins - block the activity of carrier proteins |
Which of the following protein functions is not correctly associated with the correct integral-protein? A) Channel proteins - block the activity of carrier proteins B) carrier proteins - facilitate passage of molecules through the membrane C) enzymatic proteins - catalyze a specific reaction D) cell recognition proteins - recognize pathogens |
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A) requires an input of ATP |
Active Transport A) requires an input of ATP B) is involved in diffusion C) occurs in osmosis and facilitated transport D) all of the above |
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B) phosphate heads are oriented toward the exterior of the cell or toward the cytoplasm |
In a phospholipid bilayer, the A) proteins are located only between the two layers B) phosphate heads are oriented toward the exterior of the cell or toward the cytoplasm C) fatty acid tails are ionized D) phosphate groups are hydrophobic |
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A) Integral proteins are responsible for membrane functions |
Which statement is NOT true about the proteins in the plasma membrane? A) Integral proteins are responsible for membrane functions B) Some peripheral proteins are connected to cytoskeletal filaments C) The hydrophobic portion of a protein is embedded within the membrane D) Glycoproteins contain carbohydrate chains that are oriented toward the inner surface of the membrane |
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A) polar |
Which type of molecule will require some amount of energy to cross the cell membrane? A) polarB) oxygen C) lipid D) glycerol |
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C) The movement of water across a semi permeable membrane from an area of higher water concentration to an area of lower water concentration. |
Which is the best definition of osmosis? A) The movement of a substance against its concentration gradient through the release of energy from ATP B) The movement of water across a semi permeable membrane from an area of lower water concentration to an area of higher water concentration. C) The movement of water across a semi permeable membrane from an area of higher water concentration to an area of lower water concentration. D) The movement of molecules from an area of their higher concentration to an area of their lower concentration. |
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Carrier Proteins Channel Proteins |
2 Types of Proteins that are involved in Facilitated Diffusion |
