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139 Cards in this Set
- Front
- Back
Phospholipids make up the ________of this membrane |
lipid bilayer |
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Aquaporins aid in rapid transport of _____across a membrane |
Water |
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ID Tags that are recognized by membrane proteins of other cells |
Glycoprotein |
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Proteins that recognizes neighboring cell |
Attached sugars |
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Membrane proteins may form intercellular junctions that attach adjacent cells |
Junction protein |
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Kinks in the unsaturated fatty acid tails of some phospholipids and the presence of cholesterol in animal cells keep phospholipds from packing too tightly |
Keeps a membrane "fluid" |
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Small__________molecules diffuse easily across the lipid bilayer |
nonpolar molecules |
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Each phospholipid molecule has a head that is attracted to water (hydrophilic: hydro = water; philic = loving) |
Each phospholipid molecule has a tail that repels water (hydrophobic: hydro = water; phobic = fearing). |
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Both layers of the plasma membrane have the hydrophilic heads pointing toward the outside; the hydrophobic tails form the inside of the bilayer. |
Because cells reside in a watery solution (extracellular fluid), and they contain a watery solution inside of them (cytoplasm), the plasma membrane forms a circle around each cell so that the water-loving heads are in contact with the fluid, and the water-fearing tails are protected on the inside. |
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the cholesterol that is stuck in there(plasma membrane) makes the membrane more stable and prevents it from solidifying when your body temperature is low. (It keeps you from literally freezing when you’re “freezing.”) |
Plasma membrane |
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____________key ingredient of bilogical membranes |
Phospholipids |
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Membrane need ______________________to regulate the movement of substances into and out of the cell in the origin of a cell the formation of a simple lipid bilayer membrane would not be sufficient. |
embedded proteins |
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The tendency for particles of any substance to spread out into the available space |
diffusion website study.com |
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Net movement will occur from the side of the membrane where dye molecules are more concentrated to the side where they are less concentrated |
Dye diffused down its concentration gradient |
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When both sides have equal concentrations of dye |
Dynamic equilibrium |
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When a molecule diffuse across its membrane, a cell does not have to work, therefore this movement is called
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passive transport |
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Most of the traffic across cell membranes occurs by |
diffusion |
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When O2(oxygen) enters your cells and CO2(carbon dioxide) passes out of them; this is an example of |
Diffusion down concentration graidents
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Ions and polar molecules CAN also diffuse across the hydrophobic interior of a membrane if... |
they are moving down their concentration gradients and have transport proteins to help them cross. |
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Diffusion accross a membrane is called passive transport because |
The cell does not expend energy to transport substances that are diffusing down their concentration gradient. |
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means that only certain substances areable pass through the cell membrane.A selectively permeable membrane is a membrane that only can bepermeated by selective things, in other words a surface that letssome molecules in but not others. Like a cell membrane will letwater diffuse into it :) |
Selectively permeable |
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The process of the diffusion of water across a selectively permeable membrane |
Osmosis |
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Substance that dissolves in a liquid solvent |
Solute |
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Mixture from a subtance that dissolves in a solvent |
solution |
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Net movement of water down its concentration gradient |
Osmosis |
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The lower solute concentration will move to the higher solute concentration |
What direction will the net water move? |
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The ability of a surrounding solution to cause a cell to gain or lose water is called |
tonicity |
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if an animal cell (red blood cell) is immersed in an _________________solution, the cell volume remains constant; the cell gains water at the same rate that it loses it. |
isotonic |
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IV (intravenous fluids) must be isotonic to blood cells |
True |
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Animal cells are bathed in an ______________________fluid that is isotonic to the cells |
extracellular |
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Seawater is ________________to the cells of many marine animals like sea stars and crabs |
isotonic |
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The cell gains water, swells and may burst (lyse) like an overfilled balloon when an animal cell is placed in _____________solution |
hypotonic solution |
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When an animal cell is placed in a hypertonic solution, the cell can... |
shrivel and die from water loss, |
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The ability to control the water balance to help the animal survive in a hypotonic or hypertonic environment is called |
osmoregulation |
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When a freshwater fish which lives in a hypotonic environment takes up water by osmosis across the cells of its gills and its kidneys work constantly to remove excess water from the body, this is an example of |
osmoregulation |
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Plant cell healthy environment in which the plant is turgid(very firm) would be |
hypotonic environment |
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Cell wall back pressure that occurs when the plant cell swells as water enters by osmosis |
Turgor pressure(prevents plant cell from taking in too much and bursting) |
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Plants that are not woody, such as house plants depend on their _________for mechnical support |
turgid cells |
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Just like an animal cell, when a plant cell is in a __________________environment, the plant cell loses water, shrivels and its plasma membrane pulls away from the cell wall. |
hypertonic environment |
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Plasmolysis |
A plant cell loses water, shrivels and its plasma membrane pulls away from the cell wall; |
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this process causes the plant to wilt and can be lethal to the cell and the plant |
Plasmolysis |
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Meats and other foods can be preserved with concentrated salt solutions because the cells of food-spoiling bacteria or fungi become______________ |
plasmolyzed and eventually die. |
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The function of a contractile vacuole in a freshwater Paramecium |
They are specific for the solutes they transport, the numbers and kinds of transport proteins affect a membranes permeability to various solutes. |
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The assisted transport of hydrophilic molecules and ions require the help of specific transport proteins to move across a membrane. |
Facilitated diffusion |
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The ______________is the driving force in all passive transport |
Concentration gradient |
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The ____________________ helps a specific substance diffuse across the membrane down its concentration gradient and requires no energy |
transport protein |
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Substances that use facilitated diffusion for crossing cell membranes |
sugars, amino acids, ions and water (S A W I) |
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Is a water molecule polar or non-polar |
polar |
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Waters diffusion through a membranes hydrophobic interior is relatively slow |
This slow diffusion of water is adequate |
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Cells like plant cells, red blood cell, and cells lining your kidney tubules have greater ________________ needs. |
water-permeability
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The protein channel that is the very rapid diffusion of water into and out of each cell |
aquaporin |
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Aquaporins only allow water molecule to pass through them |
true |
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In __________ transport, a cell must expend energy to move a solute against its concentration gradient |
active transport |
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The energy molecule_________ supplies the energy for most active transport. |
ATP |
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________________ allows a cell to maintain internal concentrations of small molecules and ions that are different from concentrations in its surrundings |
Active transport |
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Inside an animal cell, it has a higher concentration of Potassium ion (K+) and lower concentration of sodium ions (Na+) than the solution outside of the cell. |
Example of benefit of active transport |
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The process used to export bulky materials such as proteins or polysaccharide |
Exocytosis |
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A transport process through which a cell takes in large molecules |
2 types of endocytosis |
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Phagocytosis |
Cellular eating-a cell engulfs a particle by wrapping extensions called pseudopodia around it and packing it with a vacuole(membrane enclosed sac) |
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The vacuole then fuses with a ______________ whose hydrolytic enzymes digest the contents of the vacuole. |
lysosome |
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Protist such as amoeba take in food via |
phagocytosis |
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White blood cells engulf invading bacteria via phagocytosis |
phagocytosis |
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Specific solutes for specific molecules are embedded in regions of the membrane that are lined by a layer of coat proteins |
receptor-mediated endocytosis |
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Human cells use___________________________ to take in cholesterol from the blood for synthesis of membranes and as a precursor for other steroids. |
receptor-mediated endocytosis |
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Cholesterol circulates in the blood in particles clled (LDL's) ; These LDL's bind to receptor proteins and then enter cells by endocytois. |
Low density proteins |
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In the inherited disease familial hypercholesterolemia.... |
the LDL receptor protein are defective or missing |
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When cholesterol accumulates to high level in the blood, it leads to Atherosclerosis, which is |
the buildup of fatty deposits in the walls of blood vessels. |
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A ______ is a miniature chemical factory in which thousands of reactions occur within a microscopic space. |
Cell |
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Energy |
is the capacity to cause change or to perform work. |
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Kinetic energy |
the energy of motion. the movement of my legs can push bicycle pedals. |
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Thermal energy |
type of kinetic energy associated with the random movement of atoms or molecules. |
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Thermal energy in transfer from one object to another |
heat |
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____________, which is a type of kinetic energy can be used to power ______________________. |
Light, photosynthesis |
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Potential energy |
the 2nd main form of energy is energy that matter possesses as a result of its location or structure. |
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Molecules possess potential energy because of the arrangement of electrons in the bonds between their atoms |
true |
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Chemical energy |
potential energy available for release in a chemical reaction. |
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____________________, is the most important type of energy that can be transformed to power the work of the cell |
Chemical energy |
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The study of energy transformations that occur in a collection of matter |
thermodynamics |
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Scientist use____________for the matter under study and _______________ to refer to the rest of the universe |
system, surroundings |
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a ____________ can be an electric power plant, a single cell, or the entire planet. |
system |
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An _______________ is an open system, that is it exchanges both energy and matter with its surroundings |
organism |
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1st law of thermodynamics (law of energy conservation) |
states that energy in the universe is constant. Energy can be transferred and transformed but it cannot be created or destroyed. |
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A power plant does NOT create energy, it |
converts it from one form such as the energy stored in coal to the more convenient form of electricity. |
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The plant cell converts light energy to chemical energy...therefore |
the plant cell too is an energy transformer not an energy producer. |
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So if energy cannot be destroyed, the unavailable energy is converted to thermal energy and released as.... |
heat |
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Entrophy |
a measure of disorder or randomness |
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2nd law of thermodynamics |
energy conversions increase the entrophy(disorder) of the universe |
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The wast products emitted from the gas pipe are carbon dioxide and water (simple molecules) |
only 25% of energy stored in gas is converted to kinetic energy of car movement, the rest is lost as heat |
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Celluar respiration |
the chemical energy stored in organic molecules is used to produce ATP, which the cell can use to perform work HINT: Work-perspiration -respiration |
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Waste products in cells are also carbon dioxide and water; but cells are more efficient than cars |
Cells convert about 34%of the chemical energy in their fuel to energy for cellular work. The other 66% generates het which explains why working out makes you sweat. |
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Exergonic reaction |
releases energy |
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Think of the chemical reaction as being a |
slow burn |
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ATP |
the immediate source of energy for a cell. |
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Endergonic reactions |
require net input of energy and yield product that are rich in potential energy |
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The products of an endergonic reaction contain more chemical energy than the |
reactants do |
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Process by which plant cells make sugar is an endergonic process |
photosynthesis |
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Metbolism |
the total of an organisms chemical reactions |
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Metabolic pathway |
series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds |
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The slowburn of cellular respiration is an example of: |
metbolic pathway |
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All organisms energy comes from energy which is obtained by |
sugar and other molecules by the exergonic reactions of cellular respiration. |
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Energy coupling |
the use of energy released from exergonic reactions to drive endergonic reactions is crucial for all cells. |
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ATP Molecules are the key to energy coupling |
true |
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_____ powers nearly all forms of cellular work |
ATP |
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ATP consists of: |
organic molecule called adenosine and a triphosphate tail of 3 phosphate groups (all three groups are negatively charged) |
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The bonds connecting the phosphate groups are unstable and can be broken by |
hydrolysis, the addition of water |
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When the bond to the 3rd group breaks, a phosphate group leaves ATP which becomes |
ADP(adenosine diphosphate) and then energy is released. HINT: like passing gas energy is released |
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The hydrolysis of ATP is: endergonic or exergonic |
exergonic because it releases energy |
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When a cell couples the hydrolysis of ATP to an endergonic reaction, it does so by transferring a phosphate group from ATP to another molecule. |
Phosphorylation |
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Most cellular work depends on ATP energizing molecules by |
phosphorylating them |
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ATP is a ______________ source |
renewable; a cell uses and regenerates ATP continuously. |
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Most of the complex molecules which are rich in potential energy |
Proteins, DNA, carbohydrates, and lipids |
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Before a chemical reaction can begin, there is an______________ that must be overcome. |
energy barrier |
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Activation energy |
when energy is absorbed to contort or weaken bonds in reactant molecules so that they can break and new bonds can form; because it activates the reactants |
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The amount of energy needed for reactant molecules to move "uphill" to a higher-energy, unstable state so that the downhill part of a reaction can begin |
activation energy |
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___________________ protects the highly ordered molecules of your cells from spontaneously breaking down. |
Activation energy barrier |
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How can you speed up chemical reactions? |
HEAT: heat speeds up molecules and agitate atoms so that bonds break more easily and reactions can proceed; too much heat would kill the cell.
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_______________enzyme, the reactant must absorb energy to reach an unstable state so that reaction can proceed |
without
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_________________enzyme, it heps reactant overcome the activation energy barrier; the activation barrier is reduced by enzyme |
With |
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Enzymes |
molecules that unction as biological catalysts, increasing the rate of a reaction without being consumed by the reaction. |
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Almost all enzymes are |
proteins |
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An enzyme speeds up a reaction by |
lowering the activation energy needed for a reaction to begin |
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Substrate |
the specific reactant that an enzyme acts on |
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active site |
a pocket or groove on the surface of the enzyme |
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induced fit |
may contort substrate bonds or place chemical groups of the amino acids making up the active site in position to catalyze the reaction. |
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Cofactors |
Many enzymes require these nonprotein helpers, which bind to the active site and function in catalysis. |
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Inorganic cofactors of some enzymes |
ions of zinc, iron and copper |
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Coenzyme |
if the cofactor is an organic molecule; most vitamins are functioning as coenzymes or raw materials. |
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Folic acid |
is a coenzyme for a number of enzymes involved in the synthesis of nucleic acids |
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competitive inhibitor |
reduces an enzymes productivity by blocking substrate molecules from entering the active site |
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noncompetitive inhibitor |
does not enter the active site; instead, it binds to a site elsewhere on the enzyme and its binding changes the enzymes shape so that the active site no longer fits the substrate. |
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feedback inhibition |
if a cell is producing more of that product than it needs, the product may act as an inhibitor of one of the enzymes early in the pathway. |
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Feedback inhibition |
is irreversible |
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Ibuprofen is an enzyme inhibitor |
it inhibits an enzyme involved in the production of prostaglandins=messenger molecules that increase the sensation of pain and inflammation. |
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Enzyme inhibitors examples |
ibuprofen, blood pressure medicines and antidepressants, antiboitics, penicillin; |
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protease inhibitors |
HIV drugs that target a key viral enzyme. |
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Cancer drugs |
promote cell division |
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Pesticides and deadly poisons used in warfare |
human developed enzyme inhibitors |
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Poisons often are attached to an enzyme by covalent bonds which means
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the inhibition is irreversible.
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Anesthesia and treatment of diseases |
some drugs reversibly inhibit this same enzyme |