Biology 1, 2nd exam: CH 5, 6, & 7
Which of the following is an INCORRECT pairing between a photopigment and its characteristic or function? A. chlorophyll a: absorbs mainly green wavelengths B. chlorophyll b: absorbs mainly blue and orange wavelengths C. carotenoids: provide photoprotection D. chlorophyll b: sends absorbed energy to chlorophyll a E. chlorophyll a: sends absorbed energy to the primary electron acceptor
A
What is tonicity?
A term that describes the ability of a bathing solution to cause a cell to gain or lose water.
The product of Photosystem II is ______. The product of Photosystem I is _____. A. ATP: NADPH B. light: ATP C. NADPH: sugar D. ATP: sugar
A. ATP: NADPH
What is the major diference between autotrophs and heterotrophs? A. Autotrophs make their own food: heterotrophs consume or decompose other organisms. B. Autotrophs consume or decompose other organisms: heterotrophs make their own food. C. Autotrophs usually live on land: heterotrophs have a much wider range of habitats. D. Autotrophs usually live in water: heterotrophs live on land. E. Autotrophs are able to defend themselves: heterotrophs must rely on other organisms.
A. Autotrophs make their own food: heterotrophs consume or decompose other organisms.
Which of the following do C4 plants and CAM plants have in common? A. Both fix CO2 into an initial 4-carbon compound. B. Both fix CO2 into an initial 3-carbon compound. C. Both admit CO2 during the night only. D. Both use a single cell type for the Calvin cycle. E. Both rely on photorespiration to create sugar.
A. Both fix CO2 into an initial 4-carbon compound.
Which of the following prevents the cells of a freshwater fish from becoming hypotonic and bursting? A. osmoregulation B. osmosis C. tonicity D. aquaporins
A. osmoregulation
The two-carbon compound that enters the citric acid cycle joins with which of the following molecules before it begins its turn around the cycle? A. oxaloacetate, a 4-carbon molecule B. G3P, a 4-carbon molecule C. glucose, a 6-carbon molecule
A. oxaloacetate, a 4-carbon molecule
Both a living cell and an automobile convert fuel and ______ to the waste products ___________. In the process, ______ is produced, which represents the entropy of the reaction. A. oxygen: CO2 and water: heat B. oxygen: CO2 and water: energy C. CO2: oxygen and water: heat D. oxygen: energy and water: CO2
A. oxygen: CO2 and water: heat
Which element of a photosystem becomes reduced and then directly passes electrons to NADP+ to form NADPH? A. primary electron acceptor of Photosystem I B. primary electron acceptor of Photosystem II C. light-harvesting complexes of Photosystem II
A. primary electron acceptor of Photosystem I
Endergonic reactions _______ energy and result in products that have _____ potential energy than the reactants. A. require: higher B. release: lower C. require: lower
A. require: higher
What benefits do scientists think might result from increasing the amount of brown fat inpeople who are obese or who have type 2 diabetes? A. such people might benefit from a higher proportion of brown to white fat, which would reduce the amount of stored fat. B. brown fat is added during exercise, so it would be a good indicator of people's exercise levels. C. because brown fat is more efficient metabolically at making ATP, it could be a good alternate source of fuel for such people.
A. such people might benefit from a higher proportion of brown to white fat, which would reduce the amount of stored fat.
In the Calvin cycle, the source of CO2 is ______. The source of energy is _____ and the source of electrons for the reduction reactions is ______. A. the air: ATP: NADPH B. sugar: ATP: NADPH C. water: ATP: NADP
A. the air: ATP: NADPH
In addition to providing fuel in the form of ATP, the intermediates of cellular respiration also provide ______. A. the building blocks of proteins, fats and carbohydrates B. the substrate for anaerobic fermentation reactions C. oxygen to support life on earth
A. the building blocks of proteins, fats and carbohydrates
Several genetic disorders of mitochondria have now been identified. If such a defect resulted in a less active electron transport chain, what would you predict might occur? (Note: think of this in terms of basic mechanisms: genetic disorders rarely affect just one process.) A. the concentration of ADP within the mitochondrial matrix would increase B. the concentration of ATP within the mitochondrial matrix would increase. C. The number of electron carriers in the inner mitochondrial matrix would decrease.
A. the concentration of ADP within the mitochondrial matrix would increase.
Which of the following events takes place in the cell's cytosol? A. the formation of ATP by substrate phosphorylation B. the attachment of oxidized pyruvate to acetyl CoA C. the formation of ATP by chemiosmosis D. oxidative phosphorylation E. the generation of FADH2
A. the formation of ATP by substrate phosphorylation
Which of the following is the best description of substrate-level phosphorylation in glycolysis? A. the transfer of a phosphate group from a substrate molecule to ADP B. the transfer of a phosphate group from a substrate molecule to AMP C. the generation of ATP by ATP synthase D. the transfer of a phosphate group from ATP to a substrate molecule E. the transfer of a phosphate group from NAD+ to NADH
A. the transfer of a phosphate group from a substrate molecule to ADP.
Describe the hydrolysis of ATP.
ATP drives cellular work by coupling exergonic and endergonic reactions. Energy use involves phosphorylation reactions. Phosphorylation reactions are involved in biological work.
What is induced fit?
Active site and substrate both change shape during binding. Enzyme-substrate complex is formed. Reaction may (or may not) proceed forward. Products are formed and released. Enzyme reverts back to relaxed state.
What are some examples of cellular work?
Active transport of ions across membranes. The beating of cilia or flagella to move a cell. The contraction of a muscle to walk or run. The manufacture of polymers from monomers. The metabolic generation of heat to stay warm. The flash of a firefly.
"The capacity to cause change or do work"
Definition of Energy
Passive transport is diffusion across a membrane with no ______________________________.
Energy investment
Membrane proteins may participate in the _______________________________________ that attach adjacent cells to each other.
Intercellular junctions
What are the two main forms of energy, explain each.
Kinetic energy - the energy of motion (of waves, molecules, objects, substances). Solar/radiant energy (light, X-rays, gamma rays, radio waves) Heat energy (vibration and movement of atoms and molecules) Motion energy (moving cars, bullets, muscles) Sound energy (damaged eardrums, shattered glass, sonic boom) Potential energy - stored energy. Chemical energy (bond energy between atoms and molecules; food) Nuclear (atomic) energy (within atoms; fission and fusion of atoms) Electrical energy (batteries) Gravitational energy (energy of falling objects; waterfalls) Mechanical energy (elastic materials; springs; rubber bands)
Name some characteristics of diffusion.
Passive - no energy inputs are required. Due to the random kinetic motion (heat energy) of molecules. Occurs down a concentration gradient. One molecule moves independently of another. Continues until equilibrium is achieved. Passive transport - diffusion across a membrane.
What are the permeable molecules?
Uncharged molecules, lipid-soluble molecules, gases (CO2 and O2), and water.
Describe several characteristics of enzymes.
Very specific - can catalyze one specific reaction. Reversible - can carry out a reaction in the forward or reverse direction; brings reactions to equilibrium. Specificity is aided by shape of the active site. Active site - the part of an enzyme where the substrate binds and the catalytic reaction occurs. Originally explained as the "lock and key model" for enzymes; now replaced by the "induced fit" model.
True or False: Some proteins function as receptors for chemical messengers from other cells, or relay proteins within cells.
True
True or False: Enzymes speed up the cells chemical reactions by lowering energy barriers.
True.
Explain water balance between cells and their surroundings.
All life and life processes occur in an aqueous environment. Water moves freely across cell membranes by osmosis in response to differential solute concentrations. There is an optimum balance of water and solute across membranes. All cells must osmoregulate to maintain optimum water balance.
Each turn of the citric acid cycle yields which of the following molecules that will go on to donate their electrons to the electron transport chain? A. 3 molecules of NAD+ and 1 molecule of FAD B. 3 molecules of NADH and 1 molecule of FADH2 C. 3 molecules of NADH and 1 molecule of NAD+
B. 3 molecules of NADH and 1 molecule of FADH2
An hour of walking at 3 mph consumes approximately _____ times as much energy as an hour of sitting and writing. A. 5 B. 8 C. 2 D. 15
B. 8
Which of the following statements about brown fat is INCORRECT? A. Brown fat produces more heat and more ATP than white fat. B. Brown fat uses glucose and is metabolically very active. C. Brown fat is more metabolically active in lean than in overweight individuals. D. Brown fat metabolism is stimulated by exposure to cold. E. Brown fat helps keep infants warm.
A. Brown fat produces more heat and more ATP than white fat.
Which of the following is the summary equation for cellular respiration? A. C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP + heat B. 2C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP + heat C. C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP D. 6CO2+ 6H2O + energy→ C6H122O6+ 6O2 E. 6CO2+ 6H2O + energy→ 2C6H122O6+ 6O2
A. C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP + heat
Which of the following is a CORRECT statement about aquaporins? A. Each aquaporin molecule allows billions of molecules of water to cross the plasma membrane each second. B. Each aquaporin molecule allows thousands of molecules of water to cross the plasma membrane each day. C. When injected into frog eggs in a hypotonic solution, aquaporin messenger RNA (mRNA) slows the rate of osmosis D. People whose kidney cells have too many aquaporin proteins have to urinate very often.
A. Each aquaporin molecule allows billions of molecules of water to cross the plasma membrane each second.
The pesticide malathion and some drugs used as anesthetics both block an enzyme that is critical for transmitting nerve impulses. Why don't patients die like insects when they undergo surgery? A. Enzyme inhibition with malathion is irreversible but with anesthetics, reversible. B. Enzyme inhibition with malathion is reversible but with anesthetics, irreversible. C. The dose of enzyme inhibitor in malathion is much greater than in anesthetics. D. Insects are exposed to the enzyme for a long time, but most operations using these drugs are fairly brief. E.Enzyme inhibition with both drugs is irreversible but with anesthetics, "rescue" drugs are available.
A. Enzyme inhibition with malathion is irreversible. but with anesthetics, reversible.
What is the "fate" of oxygen after it is created in photosynthesis? A. It diffuses out of the thylakoid and eventually exits the leaf through stomata. B. It diffuses out of the thylakoid and is passed on to the Calvin cycle in the stroma. C. It remains in the thylakoid for recycling in the light reactions. D. It is removed from the thylakoid by active transport and eventually exits the leaf through stomata.
A. It diffuses out of the thylakoid and eventually exits the leaf through stomata.
Photorespiration consumes ____ and releases ____. It uses the enzyme _____. A. O2: CO2: rubisco B. O2: CO2: ATP synthase C. O2: CO2: RuBP
A. O2: CO2: rubisco
In what way, if any, does osmosis differ from simple diffusion? A. Polar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient. B. Nonpolar water molecules cluster with hydrophilic molecules, so only free water diffuses down its concentration gradient. C. They are the same process: "osmosis" is used to distinguish the movement of water from that of other molecules
A. Polar water molecules cluster with. hydrophilic molecules, so only free water diffuses down its concentration gradient.
Which of the following is a correct statement about the relationship between photosynthesis and cellular respiration? A. The products of photosynthesis are the reactants of cellular respiration, and the products of cellular respiration are the reactants of photosynthesis. B. The reactants of photosynthesis and of cellular respiration are the same, but the products of the two reactions are different. C. Both reactions use the same reactants, but in different proportions. D. Without sunlight, neither photosynthesis nor cellular respiration can occur. E. Photosynthesis and cellular respiration evolved in parallel, with approximately the same time course.
A. The products of photosynthesis are the reactants of cellular respiration, and the products of cellular respiration are the reactants of photosynthesis.
Which of the following links Photosystem II and Photosystem I in the light reactions of photosynthesis? A. an electron transport chain B. the flow of H+ ions C. ATP synthase D. microfilaments E. phosphorylation
A. an electron transport chain
________ energy is the type of ________ energy used to power the work of the cell. A. chemical: potential B. chemical: kinetic C. heat: kinetic D. thermal: potential
A. chemical: potential
Photosynthesis is an _______ process. Energy from ______ allows the production of products with ________. A. endergonic: the sun: higher potential energy than the reactants B. endergonic: the sun: lower potential energy than the reactants C. exergonic: metabolism: lower potential energy than the reactants D. endergonic: mitochondria: about the same potential energy as the reactants
A. endergonic: the sun: higher potential energy than the reactants
At what stage of active transport is ATP needed? A. for the transport protein to change its shape B. attachment of the solute to its transport protein C. release of the solute from its transport protein
A. for the transport protein to change its shape
Which is the correct sequence of events in the transfer of energy in a photosystem after a plant has been exposed to light? A. light-harvesting complex to chlorophyll a molecules to primary electron acceptor B. chlorophyll a molecules to light-harvesting complex to light reactions C. light reactions to primary electron acceptor to Calvin cycle
A. light-harvesting complex to chlorophyll a molecules to primary electron acceptor
What are the functions of membrane proteins?
Attachment proteins Receptor proteins Channel proteins Active transport proteins Junction proteins Recognition proteins Enzymes
Which of the following is the first event after a photysynthetic pigment absorbs a photon of light? A. An electron in the pigment molecule is passed to the reaction-center complex. B. An electron in the pigment molecule jumps to a higher energy level. C. An electron in the pigment molecule is used to fix carbon.
B. An electron in the pigment molecule jumps to a higher energy level.
The bubbles in dough that arise after yeast has been added are ______. A. O2, a product of alcohol fermentation B. CO2, a product of alcohol fermentation C. ethanol, a product of alcohol fermentation D. O2, a product of lactic acid fermentation
B. CO2, a product of alcohol fermentation
Which of the following processes must be present before ATP can be generated in oxidative phosphorylation? A. a lower concentration of H+ within the mitochondrial intermembrane space than within the mitochondrial matrix B. a higher concentration of H+ within the mitochondrial intermembrane space than within the mitochondrial matrix C. the presence of four electron carrier complexes within the cytosol D. a higher concentration of ATP synthase within the mitochondrial intermembrane space than within the mitochondrial matrix
B. a higher concentration of H+ within the mitochondrial intermembrane space than within the mitochondrial matrix
A plant cell placed into an isotonic solution _______. An animal cell placed into an isotonic solution _______. A. neither swells nor shrivels: neither swells nor shrivels B. becomes flaccid: neither swells nor shrivels C. remains turgid: bursts
B. becomes flaccid: neither swells nor shrivels
Before refrigeration, meat was preserved by adding ________. What effect did this have on any contaminating bacteria or fungi? A. concentrated salt solutions: swelling and bursting B. concentrated salt solutions: plasmolysis C. dilute sugar solutions: swelling and bursting D. dilute salt solutions: swelling and bursting
B. concentrated salt solutions: plasmolysis
Building a molecule of ATP is an ________process. Hydrolyzing a molecule of ATP is an _______ process. This cycle is an example of _________. A. exergonic: endergonic: energy coupling B. endergonic: exergonic: energy coupling C. exergonic: exergonic: metabolism
B. endergonic: exergonic: energy coupling
In photosynthesis, CO2 is _______ while H2O is _________. A. oxidized to C6H12O6: reduced to O2 B. reduced to C6H12O6: oxidized to O2 C. oxidized to C6H12O6: oxidized to O2
B. reduced to C6H12O6: oxidized to O2
Enzymes ______ the activation energy of a reaction. The energy change between products and reactants is _______ for a reaction that is catalyzed versus one that is not. A. lower: greater B. lower: the same C. raise: greater D. raise: the same
B: lower: the same
Enzymes are.....
Biological catalysts Not consumed in the reaction Normally proteins, sometimes RNA molecules
What are two examples of entropy-increasing energy transformations?
Both cars & cells: "burn" fuels to release energy. Give off heat and increase entropy. Automobiles: convert stored chemical (potential) energy into kinetic energy. Cells: convert stored chemical (potential) energy into metabolic energy.
One model of the cell membrane is that it is a "fluid mosaic." What does this mean? A. It consists of nucleotides, proteins and ions suspended in a fluid phospholipid bilayer. B. It consists of phospholipids suspended in a bilayer of proteins. C. It consists of proteins suspended in a fluid phospholipid bilayer.
C. It consists of proteins suspended in a fluid phospholipid bilayer.
What is the meaning of the phrase "greenhouse gases" in reference to climate change? A. Methane, water vapor, and carbon dioxide are common gases in greenhouses. B. Methane, water vapor, and carbon dioxide improve plant growth in greenhouses. C. Methane, water vapor, and carbon dioxide trap heat, as do greenhouses.
C. Methane, water vapor, and carbon dioxide trap heat, as do greenhouses.
Which of the following is a correct statement about photosynthetic pigments? A. Photosynthetic pigments are located within mitochondria. B. Photosynthetic pigments are located between the mesophyll cells. C. Photosynthetic pigments are located within the thylakoid membrane bilayer.
C. Photosynthetic pigments are located within the thylakoid membrane bilayer.
At what point in photosynthesis is sugar made? Where does this occur? A. last step of the Calvin cycle: in the stroma of the chloroplasts B. at the end of the light reactions: in the stroma of the chloroplasts C. Step 2 of the Calvin cycle: in the stroma of the chloroplasts
C. Step 2 of the Calvin cycle: in the stroma of the chloroplasts
Which of the following statements about coenzymes is correct? A. They are inorganic cofactors with enzymes in reactions. B. They speed up reactions faster than enzymes. C. They are organic cofactors with enzymes in reactions. D. They are specific for a particular enzyme.
C. They are organic cofactors with enzymes in reactions.
Walking at 3 mph burns about 245 kcal/hour. A slice of pizza contains about 474 kcal. How far would you have to walk to burn off the calories in that slice of pizza? A. about 3 miles B. about 2 hours C. about 6 miles D. about 1 mile
C. about 6 miles
Which out of the listed choices is the earliest metabolic pathway to have developed in living things? A. cellular respiration B. citric acid cycle C. glycolysis D. electron transport chain
C. glycolysis
What is the correct order of the stages of cellular respiration? A. citric acid cycle, glycolysis, oxidative phosphorylation with chemiosmosis B. glycolysis with chemiosmosis, citric acid cycle, oxidative phosphorylation C. glycolysis, citric acid cycle, oxidative phosphorylation with chemiosmosis
C. glycolysis, citric acid cycle, oxidative phosphorylation with chemiosmosis
What is the role of oxygen in the electron transport chain? A. its low electronegativity makes it the final electron acceptor B. when it combines with hydrogen, water is formed C. its high electronegativity makes it the final electron acceptor D. it high electronegativity makes it the primary electron donor
C. its high electronegativity makes it the final electron acceptor
Researchers used frog eggs to learn more about aquaporins. What characteristic of normal frog eggs was essential in these studies? A. they can translate mRNA into protein B. they are highly permeable to water C. they are largely impermeable to water D. they are surrounded by a hypertonic solution
C. they are largely impermeable to water
Why do fats make such excellent cellular fuel? A. glycerol is an intermediate in glycolysis B. they contain many calories. C. they contain many hydrogen atoms. D. they contain essential vitamins.
C. they contain many hydrogen atoms.
In what sense are living cells more efficient than internal combustion engines? A. they are much smaller B. they create more entropy C. they convert a greater proportion of fuel to useful energy D. they convert a smaller proportion of fuel to useful energy
C. they convert a greater proportion of fuel to useful energy
Glycolysis is a series of reactions that can be divided into two phases: an "energy investment" and an "energy payoff" phase. Which of the following is produced at the end of the "energy investment" phase in the metabolism of one molecule of glucose? A. two molecules of ATP B. two molecules of pyruvate C. two molecules of glyceraldehyde-3-phosphate (G3P), a 3-carbon sugar D. four molecules of ATP
C. two molecules of glyceraldehyde-3-phosphate (G3P), a 3-carbon sugar
Some membrane glycoproteins are involved in what?
Cell-cell recognition
What are the impermeable molecules?
Charged ions and molecules, macromolecules and proteins, and polar molecules.
What are "amphiphiles"?
Chemical compounds possessing both hydrophilic (water loving, polar) and hydrophobic (water fearing, non polar) properties. Phospholipids are "amphiphiles." They spontaneously form bilayers and vesicles when mixed with water. Vesicles resemble the first cells.
What are several factors that affect the rate of diffusion?
Concentration difference Temperature Area for diffusion Molecular size Resistance of diffusion medium Distance for diffusion
The splitting of one molecule of H2O in the light reactions yields which of the following? A. 2 electrons, 2 H+, O2 B. 2 electrons, 1 H+, ½ O2 C. 1 electron, 2 H+, ½ O2 D. 2 electrons, 2 H+, ½ O2
D. 2 electrons, 2 H+, ½ O2
How many molecules of ATP are produced in 1) glycolysis; 2) the citric acid cycle; and 3) oxidative phosphorylation? A. 4:2:28 B. 2:4:28 C. 2:1:32 D. 2:2:28
D. 2:2:28
What is meant by the term "enzyme specificity"? A. An enzyme is present in only one cell B. An enzyme has only one active site C. An enzyme if specific for one temperature and pH range. D. An enzyme catalyzes only one type of reaction
D. An enzyme catalyzes only one type of reaction.
At which stage of cellular respiration is the first molecule of CO2 released? A. during the citric acid cycle B. during glycolysis C. during oxidative phosphorylation D. during the oxidation of pyruvate to acetyl CoA
D. during the oxidation of pyruvate to acetyl CoA
_______ generates the ATP created in fermentation reactions. A. The citric acid cycle B. chemiosmosis C. ethanol D. glycolysis
D. glycolysis
What is one way of reducing the effectiveness of a competitive enzyme inhibitor? A. decrease the concentration of the enzyme B. increase the concentration of the competitive inhibitor C. increase the concentration of the enzyme D. increase the concentration of the substrate
D. increase the concentration of the substrate
As an energy source, photoautotrophs use ______; chemoautotrophs use _______; and heterotrophs use ________. A. photosynthesis; inorganic chemicals; cellular respiration B. photosynthesis; photoautotrophs; cellular respiration C. fluorescence; inorganic chemicals; photoautotrophs D. light; inorganic chemicals; photoautotrophs
D. light; inorganic chemicals; photoautotrophs
Which method of transport uses coated pits? A. vacuole-mediated endocytosis B. phagocytosis C. facilitated diffusion D. receptor-mediated endocytosis
D. receptor-mediated endocytosis
What is the driving force for the production of ATP in the light reactions? A. the sun B. the electron transport chain in the thylakoid membrane C. the H+ concentration gradient across the mesophyll membrane D. the H+ concentration gradient across the thylakoid membrane
D. the H+ concentration gradient across the thylakoid membrane
Chemical reactions either release or store energy, describe exergonic vs. endergonic reactions.
Exergonic (exothermic): give off energy, products have less energy than reactants (e.g. cellular respiration) Endergonic (endothermic): consumes (requires) energy, products have more energy than reactants (e.g. photosynthesis) Metabolism: the sum total of an organism's reactions, divided into metabolic pathways. Anabolism means builds up molecules. Catabolism means breaks down molecules. Involves energy coupling via ATP.
Some "attachment proteins" help coordinate what?
Help coordinate physical changes inside and outside the cell through their attachment to the cytoskeleton and extracellular matrix.
Describe the three types of "tonic" solutions.
Hypotonic - solute concentration outside the cell is less than inside the cell; water enters the cell. (animal cell: lysed. plant cell: turgid or normal) Isotonic - solute and water concentration inside and outside of a cell are equal; no net water movement. (animal cell: normal. plant cell: flaccid) Hypertonic - solute concentration outside the cell is greater than inside the cell; water leaves the cell. (animal cell: shriveled. plant cell: shriveled)
Define Energy Transformations.
Living systems function by transforming one form of energy into another.
What are mechanisms of action with enzyme inhibitors?
Mechanisms of action: Competitive inhibition: inhibitor has a similar shape as substrate, inhibitor binds to active site, preventing binding of substrate, and inhibitor "competes" with substrate for active site. Non-competitive inhibition: inhibitor has a different shape than substrate, binds to an allosteric ("other shape") site, and binding of inhibitor changes shape/affinity of active site.
What are aquaporins?
Membrane bound transport proteins that facilitate the diffusion of water across membranes. Especially important in cells that process a lot of water, like kidney cells and plant cells involved in symplastic transport.
What is the fluid mosaic model for membrane structure?
Membranes are composed of a bilayer of phospholipids in the fluid state. Double bond in fatty acids prevent packing. Head groups towards surface; fatty acids inwards. Integral proteins are embedded in the membrane; peripheral proteins are loosely attached. Proteins and lipids freely move about in the membrane. "Mosaic" = patchwork.
Describe the second law of thermodynamics.
No energy transformation process is 100% efficient. Every transformation involves the loss of heat energy. Heat energy is a "disordered" form of energy that is unavailable to do work (aka entropy). Every energy transformation increases the disorder of the universe. Entropy is the measure of disorder or randomness.
Define the Laws of Thermodynamics.
Rules to help explain energy transformations and flow.
Membranes may exhibit ______________________________, allowing some substances to cross more easily than others via ________________________ (or facilitated diffusion).
Selective permeability Simple diffusion
What are liquid rafts?
Solidified subdomains of the plasma membrane enriched in cholesterol, glycosphingolipids contains saturated fatty acids, and signal proteins. Freely "float" in the fluid lipid bilayer. Thought to be involved in signal transduction.
What is osmosis?
The diffusion of water across a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration. Solutes do not (readily) cross membranes. Water molecules are attracted to solute molecules. Water levels (or pressure) change accordingly. In a "closed system", little water moves; but osmotic pressure increases.
What is active transport?
The energy dependent transport of a substance across a biological membrane. Involves the hydrolysis of ATP and specific transport proteins. Results in transport and accumulation against a concentration gradient. Includes endocytosis and exocytosis.
What is facilitated diffusion?
The passive carrier-mediated transport of a substance across a biological membrane down a concentration gradient. Some proteins form a hydrophilic tunnel for passage of specific ions or molecules. Other proteins specifically bind substances, change their shape, and release them on the other side.
Define Endocytosis.
The process by which extracellular materials are taken into a cell via the infolding of the plasma membrane and the formation of vesicles.
Define Exocytosis.
The process by which the contents of intracellular vesicles are released to the outside of a cell by fusion with the plasma membrane.
What is diffusion?
The spontaneous net movement of a substance from a region where it has a high concentration to a region where it has a low concentration, OR, the tendency of particles to spread out evenly in an available space.
Define Thermodynamics.
The study of energy transformation that occur in a specific collection of matter.
Describe the first law of thermodynamics.
The total amount of energy in the universe is constant. Energy can be transformed from one form into another, but it cannot be created or destroyed.
