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Bio-Exam 2-Chap 5
Terms in this set (67)
Phospholipids organized in two layers wherein their hydrophobic tails are projecting inward while their polar head groups are projecting outward
Fluid mosaic model
Phil Flows Pretty Bad
Description of the membrane of a cell.
-phospholipids of a cell membrane, which, like liquid, flow.
-proteins embedded in the phospholipid bilayer that act as conduits through which molecules enter and exit the cell.
How can proteins be positioned within the membrane?
Intergral Proteins: bound to the hydrophobic interior of the phospholipid bilayer
Peripheral Proteins: lie on either side of the membrane but are not bound to its hydrophobic interior.
The functional types of membrane proteins and their function.
Sophie Is Always Excited Come Tuesday
S- signal transduction
I- intercellular joining
A- attachment (to the cytoskeleton and extracellular matrix)
E- enzymatic activity
C- cell-cell recognition
Selectively permeable membrane.
Only certain substances are able pass through the cell membrane.
Substances that can freely cross cell membranes?
Substances that are not able to freely cross cell membranes?
The movement of molecules or ions from a region of their higher concentration to a region of their lower concentration.
Defines the difference between the highest and lowest concentrations of a solute within a given medium.
What is the relationship between the concentration gradient of a substance across a membrane and potential energy?
The concentration gradient of a substance across a membrane represents potential energy because it drives diffusion. Nonpolar and small polar molecules can pass through the cell membrane, so they diffuse across it in response to concentration gradients.
What factors affect the rate of diffusion?
Sarah Loves To Sip Cold Coffee
L- Lipid Solubility
C- Charge (+/-)
How does size affect the rate of diffusion?
Small molecules can slip by the polar heads of the phospholipids and through the membrane to the other side. Oxygen gas, carbon dioxide and water can move in this manner. Very large molecules like proteins cannot diffuse across the membrane at all.
How does shape affect the rate of diffusion?
Glucose is able to get into cells much faster than other sugars. This is accomplished by facilitated diffusion. A carrier protein specific for glucose (not other sugars) combines with it on the outer surface, closes around it, and then opens to the inside of the cell where the glucose is released. The carrier then returns to its original shape and is ready to transport another glucose molecule. These carriers can move up to 100 glucose molecules per second across the cell membrane.
How does concentration affect the rate of diffusion?
The greater the concentration gradient between the outside and inside of the membrane the greater the rate of diffusion. If the concentration of oxygen outside the cell increases then it will diffuse more quickly into the cell. The opposite is also true. If a muscle cell for example is working hard and using up large quantities of oxygen in cellular respiration producing ATP, then the low levels inside the cell will increase the concentration gradient compared to outside and the rate of diffusion of oxygen into the cell will increase. The same conditions in a muscle cell would create high concentrations of carbon dioxide inside the cell and increase the rate of diffusion from inside to outside.
How does charge (+/-) affect the rate of diffusion?
Ions or molecules with a charge cannot pass through the lipid bilayer by diffusion. Other mechanisms involving protein carriers and ATP energy are required. The sodium/potassium ion pump is an example of this type of transport.
How does lipid solubility affect the rate of diffusion?
Lipid soluble molecules can move through the lipid bilayer.
How does temperature affect the rate of diffusion?
In general, increases in temperature cause all molecules to move faster. Diffusion is a passive movement of molecules so quicker molecule movement translates into quicker diffusion.
The rate of diffusion increases as....?
*Diffusion distance decreases
*Concentration gradient increases
*Surface area increases
Transport that does not require energy
When the cell does not expend energy when substances diffuse down their concentration gradient.
Transport that requires energy
Requiring the expenditure of energy to transport a solute against its concentration gradient; essential for a cell to maintain internal concentrations of small molecules that differ from environmental concentrations.
The diffusion of water across a selectively permeable membrane.
How is the direction of water movement based on differences in solute concentrations?
Depends on how the water diffuses down its own concentration.
Hypo sounds like hippo; Hippo's are fat, and if they get too fat they will pop. silently repeat the phrase: Hypo, hippo, fat, pop, before answering any questions on the distinction between these two definitions.
Hypertonic solutions, have a high concentration of solutes, like sugar makes you hyper.
When the cell loses water and shrivels.
A cell will lose water to a surrounding solution that is hypertonic- a solution that has a greater concentration of solutes in it than does the cell's cytoplasm.
In a hypOtonic solution, the cell will swell up like an "O"
the cell gains too much water, swell, and possibly lyse (burst).
A cell will gain water when the surrounding solution is hypotonic to the cytoplasmic fluid.
Equilibrium; when the cell neither gains or lose water.
Water flow is balanced between the cell and its surroundings when the surrounding fluid and the cytoplamic fluid are isotonic to each other- when they have the same concentration of solutes.
How are cells are able take in or expel large molecules or particles?
Larger materials are brought into the cell through endocytosis and moved out through excoytosis. Both mechanisms employ veicles, and the membrane-lined enclosures that alternately bud off from membranes or fuse with them.
Some substances are broken down (catabolism) to yield energy for vital processes while other substances, necessary for life, are synthesized (anabolism).
The capacity to bring about movement against an opposing force.
(A car parked at the top of a hill)
energy in motion
(A car rolling down a hill)
Study of energy transformations that occur in a collection of matter
First law of Thermodynamics
Energy is never created or destroyed, but is only transformed.
Second law of Thermodynamics
Energy transfer will always result in a greater amount of disorder in the universe.
amount of disorder in a system;
the greater the entropy, the greater the disorder. In line with the second law of thermodynamics- some energy will be lost to the most disordered form of energy: heat.
Energy is released in exergonic reactions, in which the reactants contain more energy than the products.
Energy in living things is stored away in endergonic reactions in which the products of the reaction contain more energy than the reactants.
ATP Reads Poetry
An adenosine-derived nucleotide, that contains high-energy phosphate bonds and is used to transport energy to cells for biochemical processes.
Adenine, Ribose, 3 phosphate groups.
How is ATP used to couple exergonic and endergonic reactions?
linked in coupled reactions- reactions in which an energy yielding exergonic reaction powers an energy-requring endergonic reaction.
The molecule most often is used in living things to power coupled reactions is ATP. ATP's energy transfer powers stem from the fact that it contains three phosphate groups: each of which is negatively charged; meaning these groups repel each other.
What is the function of enzymes (as catalysts) in biological systems?
(Catalysts-somebody or something that makes a change happen or brings about an event.)
Accelerates the rate at which a chemical reaction takes place in an organism. Drives chemical reactions by donating its third phosphate group to them.
The substance that an enzyme helps transform through chemical reaction
The active part of enzyme.
The portion of an enzyme that binds with a substrate - thus transforming it.
; typically, a pocket or groove on the enzyme's surface.
One of the compounds that form between the initial reactant and the final product in a metabolic pathway, such as between glucose and pyruvate in glycolysis.
An ending material in a chemical reaction.
A non-protein molecule or ion that is required for the proper functioning of an enzyme.
An organic molecule serving as a cofactor. Most vitamins function as coenzymes in important metabolic reactions.
Explain the relationship between enzyme structure and specificity?
The shape of the enzymes are different to only allow certain molecules into the active sites.
The specificity of an enzyme is dependant on the structure of the enzyme for a few reasons:
1) Depending on the structure of the enzyme, and therefore the shape of the enzymes active site, a substrate may be more or less effective at binding to the active site. As the active site is generally shaped for a particular substrate that works only with that particular enzyme, the shape of the active site as a result of the enzyme structure can influence which substrates the enzyme can and cannot bind with.
Describe some mechanisms by which enzymes lower activation energy.
4- Orienting, Straining, Providing, Covalently.
1. orienting(direction) substrates correctly
2. straining substrate bonds
3. Providing a favorable micro environment
4. Covalently bonding to the substrate
Predict the effects of enzyme and substrate concentrations on the rate of the reaction.
No substrate = no reaction
As substrate concentration increases, enzyme activity should increase until it reaches a maximum when all of the enzyme is taken up by substrate.
How does energy flow through the biosphere?
Sun -> Producers (^heat) -> Consumers (^heat) -> Decomposers (^heat)
(can go from producers straight to decomposers as well)
How do nutrient cycle through the biosphere?
Producers -> Consumers -> Decomposers -> Inorganic Nutrient Pool -> Back to producers
(can go from producers straight to decomposers as well)
all areas on Earth that can sustain life and are inhabited by organisms (air, water, land)
balance in a system; the overall fluctuations in the system balance out and there is no net change over time
organisms that are able to produce their own food (energy) by harnessing chemical or solar energy; also called autotrophs
organisms that must obtain their food (energy) by eating other organisms (producers or consumers); also called heterotrophs
An organism that breaks down dead organisms and other organic waste
What is the role of activation energy in a chemical reaction?
the minimum energy that the reactant particles must possess at the time of collision in order for a chemical reaction to take place.
Control of the rate of a reaction catalyzed by an enzyme by some effector.
a phenomenon in which the end product of a reaction or sequence of reactions inhibits the enzyme or enzyme cascade. When sufficient product is produced, the system automatically turns itself off.
allosteric control (noncompetitive inhibition)
Molecule binds with the enzyme at a site other than its active site.
Such binding changes the enzymes shape, thereby decreasing or increasing the enzyme's ability to bind with its substrate. This causes enzymes to not have to turn out product in strict accordance with the amount of substrate in their environment; rather enzyme activity can be finely tuned in accordance with cellular needs.
Reduction in the activity of an enzyme by means of a compound other than the enzyme's usual substrate binding with the enzyme in its active site.
How does temperature effect enzyme activity?
Increases enzyme activity until it peaks, at which point further increases decrease activity by denaturing the enzyme.
How does pH effect enzyme activity?
Enzymes are picky with pH levels, as they are with every thing else.
They have an optimal level at which they work the best, and anything above or below that level, their activity begins to slow down until they shut down all together.
(Which is referred to as denaturing the enzyme)
How does salinity effect enzyme activity?
Higher salinity may promote binding of a hydrophobic substrate to an enzyme, or of hydrophobic residues to each other within the enzyme to ensure optimal folding for enzymatic activity.
Series of chemical reactions occurring within a cell. In each pathway, a principal chemical is modified by a series of chemical reactions.
Cata-polts (releases) energy
Release energy by breaking down complex molecules to simpler compounds.
(Anna consumed the banana)
Anna consumed the banana
Consume energy to build complicated molecules from simpler ones.
three ribosome sites
A (arrive) P (park) E (exit)
Recommended textbook explanations
Fundamentals of Biochemistry
Charlotte W. Pratt, Donald Voet, Judith G. Voet
Campbell Biology (AP Edition)
Cain, Jackson, Minorsky, Reece, Urry, Wasserman
Miller and Levine Biology
Joseph S. Levine, Kenneth R. Miller
Biocalculus: Calculus for the Life Sciences
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