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141 Cards in this Set
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Metabolism
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sum total of all chemical reactions occurring in the cell in an organism
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Catabolism
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one of the components of metabolism: metabolic pathways that release energy by breaking down complex molecules into simpler compounds (ex. cellular respiration)
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break down
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Anabolism
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Metabolic pathways that consume energy by building complex molecules from simpler ones
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build up
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Energy
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the capacity to do work
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kinetic energy
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energy of motion
: one of fundamental types of energy |
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potential energy
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energy that matter possesses because of its structure or location
: one of fundamental types of energy |
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chemical energy ( not one of two basic fundamental energies)
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type of kinetic energy: stored i nmolecules because of the structural arrangement of the atoms in those molecules
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are the basic types of energy interconvertible?
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yes
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Free energy
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that portion of a system's energy that is available to perfom work
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are free energy and process sponaneity related?
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yes
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a spontaneously occurring process will always involve...
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a loss of free energy ( delta G will be negative : energy is released)
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processes that DO NOT occur spontaneouly require...
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an input of energy if they are going to occur ( delta G will be positive: energy increases)
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Exergonic
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free energy is released during reaction
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1 of fund. types of chem. reactions in metabolism
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Endergonic
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free energy is absorbed during reaction
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are exergonic and endergonic reactions coupled in metabolism?
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yes
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ATP
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Adenosine Triphophate
Contains potential chemical energy - the molecule that is used to carry out most cellular work |
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what ultimately allows work to be performed?
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the hydrolysis of the phosphate bonds is an exergonic reaction that is coupled to endergonic reactions
: ex : active transport, ATP hydrolysis, changes in protein shape (confirmation) 8.14 |
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Mechanical work
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changes in shape ; movement
: one of 3 basic types of cell work |
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transport work
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movement of substancecs across the embrance against the concentration gradient
:1 of 3 cell work |
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chemical work
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pushing of endergonic reactions )in most cases this pushing coupled o exergonic reactions)
: 1 of 3 cell work |
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Enzymes are what?
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protein catalysts
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2 words
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catalyst
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an chemical agent (like protein) that changes the rate of how fast a chemical reaction occurs withouth being consumed in the reaction
:does not change spontanaeity |
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enzymes work by lowering what?
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energy of activation in a chemical reaction
: this increases the rate of the reaction (ho fast occurs) so that the normal metabolism of the cell cna be maintained; however, enzymes do not have capacity by themselves to make nonspontaneous reactions occur (this requires energy) |
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enzymes allow less energy to activate reaction
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goes from high energy to low energy and reuses recycled enzymes
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enzymes are substrate specific
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3D fit between an enzyme and its substrate and "induced fit"
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induced fit
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a slight change in the active site of a protein upon binding of substrate such that the binding affinity is increased
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active site
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key part:
where the chemistry occurs :catalytic center of enzyme :part(s) of the substrate molecule(s) to be effected are held in close proximity |
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will the internal environment of the cell affect enzyme activity?
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yes
:important environmental factors include: pH (acidity), temperature, cofactors like vitamins |
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Control of Metabolism:
Competitive Binding |
a molecule that directly affects active site by competitive binding will have an overall shpare tha tis similar to the substrate
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Control of Metabolism:
Noncompetive Binding |
indirectly affects active site by binding a site away from the active site, but overall protein shape is changed as is the conformaion of the active site
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Control of Metabolism:
Allosteric Regulation |
allosteric enzymes are typically composed of several subunits; binding to the allosteris sie )away from the active site) may simultaneously change all active sites of the individual subunites such that the enzyme is activated or inhibited
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Control of Metabolism:
Cooperativity |
binding of a single substrate molecule to one of several subunits results in induced fit and activation of active sites on other subunits
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Control of Metabolism:
Notes |
Feedback inhibition of a metabolic pathway - localization of enzymes w/in the cell
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Cellular Respiration
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metabolic process by which organisms convert the energy present in organic molecules to ATP and byproducts
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Glucose: Summary Equation
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Organic Molecule + Oxygen = CO2 + H2O + ATP + HEAT
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mitochondrial structure
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outer membrane, inner membrane, intermembrane space, matrix
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3 parts of cellular respiration:
oxidative phophorylation |
generates most of the ATP
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3 parts of cellular respiration:
glycolysis |
occurs in the cytosol; generates 2 ATP and some high energy molecules (2 NADH) that will drive oxidative phosphorylation
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3 parts of cellular respiration:
krebs cycle |
occurs in the mitochonrial matrix; generates some ATP(2) and alot of high energy molecules (10) that will be used to drive oxidative phos.
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oxidative phosphorylation
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Oxidation/Reduction reactions and the pumping of protons across the inner membrane of the mitochondrion
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Oxidation/Reduction (Redox) Reactions
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involves the transfer of electrons from one molecule to another
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oxidized
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the molecule that losses electrons:
(LEO, loss of electrons is oxidation |
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reduced
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the molecule that gains electrons:
GER = (Gain of electrons is reduction) |
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X(e-) + Y ------------> X + Y(e-)
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in this example, molecule X is the reducing agent (which is oxidized) and molecule Y is the oxidizing agent (which is reduced)
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when electrons are transferred between molecules they lose ...
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some enrgy with each transfer
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what are pumped from matrix side of the mito to the inner membrane side by a hydrogen-electron transport chain (HETS)?
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protons (H+)
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HETS
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series of proteins located within or on the inner membrane that function in a series of redox reactions
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as e- move through the HETS chain they progressively ...
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lose energy,
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some of this energy is used to transport WHAT across the membrane?
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H+
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when a protein in the chain receives e- (is reduced) it gains energy, but losses energy when it is oxidized
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the HETS is a series of exergonic and endergonic reactions that are coupled
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certain proteins in the HETS will use the free enrgy that accompanies the redox reaction to do WHAT?
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to transfer eletrons across the inner membrane
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In the HETS, the proteins are organized in such a way that there is a...
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continnuum of increasing electronegativity; this results in the orderly flow of electrons “downhill” toward a terminal electron acceptor (oxygen)
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The initial electron donors in oxidative phosphorylation are...
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high energy reducing agents that are generated in the Krebs cycle and in Gylcolysis
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How many reducing agents are used??
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2: (NADH, and FADH2 are used)
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How many protein complexes comprise the HETS?
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3: (NADH-Coenzyme Q Reductase, Coenzyme Q -Cytochrome C Complex, Cytochrome C Oxidase Complex)
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Do electrons flow sequentially through these complexes?
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Yes
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each complex is comprised of many ...
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proteins, but only a few of these proteins actually function in the transfer of protons across the inner membrane
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these electrons are transferred through the complxes with a particular # of H+ being transfered by some of the proteins of the respective complexes
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NADH-Coenzyme Q Reductase - 4H+
Coenzyme Q -Cytochrome C Complex - 6H+ Cytochrome C Oxidase Complex - 2H+ |
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Note that each NADH transfers 2e- through each of these complxes and is therefore responsible for the movement of 12H+ across the inner membrane
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In contrast FADH2 initially donates 2e- to Coenzyme Q -Cytochrome C Complex and is ultimately responsible for the movement of 8e- across the membrane
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Note that oxygen is the terminal electron acceptor in the formation of water
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2e- + 2H+ + 1/2O2 ------> H2O
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protomotive force
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The proton gradient that results
pmf = concentration gradient + charge speration (voltage potential) *most of the potential energy of the protomotive force is embodied in the charge potential |
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Use of PMF to Generate ATP:
ATP Synthase Complex (mitochondrial lollipops) |
a large complex of protiens that has two major components (a stem called Fo and a head called F1 that actually synthesizes ATP from ADP + Pi)
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as eletrons flow through channels in Fo conformational changes occur in F1 that lead to the generation of...
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ATP
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for every 4H+ that move through how many ATP molecules are generated?
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1
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Krebs Cycle
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occurs in the matrix of the mito., generates NADH, FADH2, and some ATP, as well as CO2 as a byproduct
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pyruvate
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starting molecule that enters the Krebs cycle
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for each pyruvate the cycle will generate ?? NADH, ??FADH2, ?? ATP, and the ?? CO2
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4 NADH, 1 FADH2, 1ATP, and the 3CO2
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For each starting glucose, ?? pyruvate are generated during glycolysis;
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2
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per glucose the Krebs cycle generates:
• 6CO2 as byproducts • 8 NADH = 24 ATP equivalents • 2 FADH2 = 4 ATP • 2 ATP are drectly produced |
for a total yield 30 ATP equivalents from the Krebs cycle
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Glycolysis
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splitting of glucose into two three carbon molecules with the release of energy; occurs in the cytosol and the endproduct (pyruvate is transported into the mitochondrion); no oxygen is required
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glucose is split into two glyceraldehyde 3-phospahte molecules (with several intermediate molecules and each step catalyzed by enzymes)
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note that included in these reactions is the addition of two phospahte groups, so two ATP molecules are consumed in these initial reactons (energy of activation)
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each glyceraldehyde 3-phospahte then has an inorganic phospahte added (no ATP consumed);
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this addition is highly exergonic and is coupled to the reduction of NAD+; the product of this step is 1,3 bisphosphoglycerate
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each 3 phosphoglycerate is converted to pyruvate and a single molecule of ATP is produced via substrate level phosphorylation
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each 1,3 bisphosphoglycerate is then dephopsphorylated in substrate level phosphorylation to produce a molecule of ATP; the product is 3 phosphoglygerate
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Summary - Products and byproducts
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A. Gylcolysis - 2 NADH + 2 ATP
B. Krebs Cycle - 8 NADH + 2FADH2 + + 2ATP + 6CO2 C. Oxidative Phosphorylation - 34 ATP + 12 H2O (O2 consumed) D. C6H12O6 + 6O2 -------> 38 ATP + 6CO2 + 6H2O |
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Cellular Respiration and Physiological Conditios (with respect to O2)
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Pyruvate is a key intermediate.
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Krebs Cycle
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occurs in the matrix of the mito., generates NADH, FADH2, and some ATP, as well as CO2 as a byproduct
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pyruvate
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starting molecule that enters the Krebs cycle
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for each pyruvate the cycle will generate ?? NADH, ??FADH2, ?? ATP, and the ?? CO2
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4 NADH, 1 FADH2, 1ATP, and the 3CO2
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For each starting glucose, ?? pyruvate are generated during glycolysis;
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2
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per glucose the Krebs cycle generates:
• 6CO2 as byproducts • 8 NADH = 24 ATP equivalents • 2 FADH2 = 4 ATP • 2 ATP are drectly produced |
for a total yield 30 ATP equivalents from the Krebs cycle
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Glycolysis
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splitting of glucose into two three carbon molecules with the release of energy; occurs in the cytosol and the endproduct (pyruvate is transported into the mitochondrion); no oxygen is required
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glucose is split into two glyceraldehyde 3-phospahte molecules (with several intermediate molecules and each step catalyzed by enzymes)
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note that included in these reactions is the addition of two phospahte groups, so two ATP molecules are consumed in these initial reactons (energy of activation)
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each glyceraldehyde 3-phospahte then has an inorganic phospahte added (no ATP consumed);
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this addition is highly exergonic and is coupled to the reduction of NAD+; the product of this step is 1,3 bisphosphoglycerate
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each 3 phosphoglycerate is converted to pyruvate and a single molecule of ATP is produced via substrate level phosphorylation
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each 1,3 bisphosphoglycerate is then dephopsphorylated in substrate level phosphorylation to produce a molecule of ATP; the product is 3 phosphoglygerate
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Summary - Products and byproducts
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A. Gylcolysis - 2 NADH + 2 ATP
B. Krebs Cycle - 8 NADH + 2FADH2 + + 2ATP + 6CO2 C. Oxidative Phosphorylation - 34 ATP + 12 H2O (O2 consumed) D. C6H12O6 + 6O2 -------> 38 ATP + 6CO2 + 6H2O |
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Cellular Respiration and Physiological Conditions (with respect to O2)
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Pyruvate is a key intermediate.
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Photosynthesis
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the generation of carbohydrate using light energy:
Requires carbon dioxide and water as reactants - Byproducts are oxygen and water |
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Photosynthesis Summary Equation
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6CO2 + 12H2O -----> C6H12O6 + 6O2 + 6H2O
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the ????? of CO2 is incorporated into carbohydrate using high energy molecules produced using sunlight energy
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carbon
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what drives an electron trnsport chain that is used to make these high energy molecules?
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sunlight
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what comes from the water moleule (splitting of water)?
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oxygen
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what are the primary photosynthetic organs of plants?
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leaves
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what are the organelles within which photosynthesis occurs?
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cholorplasts
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chloroplasts contain chlorophyll which is...
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a pigment which is capable of absorbing sunlight energy
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there are HOW MANY types of chlorophyll molecules?
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3 : each having slightly different absorption characteristics
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(most land plants have ....
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both chl. a and b
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chlorophyll molecules are organized into photosystems on the
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thylakoid membranes
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the photosystem consists of
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antennae chlorophyll molecules, a rection center chlorophyll, and associated proteins
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WHAT is transferred from the antennae chlorophyll molecules to the reaction center chlorophyll where WHAT begins?
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light energy - electron transport
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Light Reactions
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1. require light
2. occur on the surface of the thylakoids 3. generate ATP and NADPH 4. require H2O and release O2 as a by product 5. involves a electron trnsport chain similar to that of cellular respiration |
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The light reactions involve the coordinated action of two WHAT?
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photosystems: PS 1 AND PS 2
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cyclic electron flow
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produces nearly equal quanties of ATP and NADPH as well as consumes H2O and produces O2 as a by product
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noncyclic electron flow
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(from Fd of PSI to Cyt C of PSII) produces ATP only
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PSII
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1. has the OEC and thus consumes H2O and liberates O2
2. generates the protomotive force (ATP synthesis) |
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PSI
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1. receives e- from PSII and produces NADPH
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The Calvin Cycle
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(light independent reactions)
1. can occur in either the light or dark 2. uses the high energy molecules produced in the light reactions to make carbohydrate |
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Cell Wall (Plant Cells)
Function |
protection, maintains cell shape, support
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Cell Wall Structure
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1. the cell wall of higher plants is composed of numerous overlapping cellulose fibers
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Primary Type of Cell Wall
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thin and pliable, and allows for growth of the cell; produced first as the cell matures
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Secondary Cell Wall
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much more rigid and thicker than primary cell wall; produced after the primary wall
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Plasma Membrane Function
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1. regulates the passage of substances into and out of the cell
2. is selectively permeable : certain small molecules will diffuse across the PM (O2, CO2, H2O): |
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Plasma Membrane Structure
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1. is fundamentally a phospholipid bilayer that contains some associated protein
2. the membrane is structurally dynamic (the functional membrane is somewhat like a fluid or gel) |
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Movement Across Membranes:
diffusion |
spontaneous movement of molecules down a concentration gradient
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Movement Across Membranes:
osmosis |
diffusion of water across the membrane
unlike solute, water moves from hypotonic to hypertonic solutions |
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facilitated diffusion
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protein assisted
allows larger as well polar molecules to cross the PM down a concentration gradient |
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diffusion, fac. diffusion, and osmosis are...
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passive processes (passive transport)
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Active transport
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requires energy (ATP) and proteins in order to occur; substances are moved against their concentration gradient
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Nucleus
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The largest and most conspicuous organelle
B. Enclosed by a double membrane that comprises the nuclear envelope |
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Nucleus' Nuclear Envelope
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has pores that regulated the movement of molecules into and out of the nucleus
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The nucleus contains most of the cell’s DNA in the form of chromatin
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chromatin = DNA + bound protein
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Ribosomes
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. Site of protein synthesis
B. May occur freely or bound to membranes of the ER |
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Endomembrane System
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an integrated set of membranes within the eukaryotic cell (integrated = they work together to accomplish certain functions and, in some cases, are physically joined
:these membranes are “integrated” in that they are physically joined or communicate through vesicles: |
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vesicle
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a “packet “of substances that are surrounded by a membrane
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Endomembrane System consists of...
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consists of the nuclear membrane, endoplasmic reticulum, golgi apparatus, lysosomes, and vacuoles
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Endoplasmic Reticulum (ER)
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A. A complex of membranes folded into sac-like structures that are joined with the nuclear membrane
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2 Types of ER:
Smooth Rough |
Smooth - no bound ribosomes
Rough - has bound ribosomes |
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Functions of the ER
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Synthesis of phospholipids (Smooth ER)
Breakdown of drugs and other toxic substances Manufacture of proteins that will be secreted outside the cell or deposited in the plasma membrane |
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Golgi Apparatus (GA)
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Made of flattened sacs (cisternae) that modifies, stores, and routes products from the ER
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Functions of the GA
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chemical modification of proteins and phospholipids synthesized in the ER
• directs proteins, phospholipids, and other molecules to other places in the cell |
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Lysosomes
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A membrane enclosed bag of hydrolytic (digestive) enzymes
- enzymes within lysosomes are capable of digesting almost any kind of molecule |
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Functions of Lysosomes
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intracellular digestion
• recycling of macromolecules within the cell • programmed cell destruction |
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Vacuoles (Plants)
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A compartment (usually large) that is membrane bound
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Vacuoles function in:
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storing food (formed by phagocytosis)
2. pumps (contractile vacuoles) storage (central vacuoles of plants) |
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Mitochondria
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-"powerhouse" of the cell (site of ATP production)
Organic molecule + oxygen = CO2 + H2O + ATP + Heat |
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Chloroplast
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site of photosynthesis:
Light + CO2 + H2O = carbohydrate + oxygen |
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Cytoskeleton
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a network of fibers that forms a framework for support, provides a means for movement, and enables a cell to maintain and change shape
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Peroxisomes
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. organelles that contain enzymes that metabolize oxygen and peroxide
B. additional functions include: - breakdown of fatty acids - detoxification of alcohol and other toxic substances |
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Hypertonic Solution:
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Solute concentration higher than cell
More dissolved particles outside of cell than inside of cell Hyper = more (think hyperactive); Tonic = dissolved particles Water moves out of cell into solution Cell shrinks |
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Hypotonic Solution:
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Solute concentration lower than cell
Less dissolved particles outside of cell than inside of cell Hypo = less, under (think hypodermic, hypothermia); Tonic = dissolved particles Water moves into cell from solution Cell expands (and may burst) |
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Solute
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dissolved particle
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Solvent
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liquid medium in which particles may be dissolved
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