micro ch 6
11. Proton Motive Force
Form of energy generated as an electron transport chain moves protons across a membrane to create a chemiosmotic gradient.
8. Oxidative Phosphorylation
Synthesis of ATP using the energy of a proton motive force created by harvesting chemical energy.
9. Photophosphorylation
Synthesis of ATP using the energy of a proton motive force created by harvesting radiant energy.
12. Substrate-Level Phosphorylation
Synthesis of ATP using the energy released in an exergonic (energy-releasing) chemical reaction during the breakdown of the energy source.
oxidative phosphorylation-practice question
energy from exergonic reactions is used to create a proton motive force that drives the addition of P, to ADP
kinetic energy
energy of motion. such as movement of water from behind a dam
substrate-level phosphorylation-practice question
energy released in an exergonic reaction is used to power the addition of P, to ADP
free energy
energy that is available to do work
the statement "the substrate fits into the active site of an enzyme like a hand into a glove" refers to what important property of enzymes?
enzyme specificity
substrate-level phosphorylation
exergonic chemical reaction
reduction
gain of electrons
reducing power
generated by the three central metabolic pathways [in the form of NADH, FADH2, and NADPH]. reducing electron carriers such as NADH, NADPH, FADH2; their bonds contain a form of energy that can be used by a cell. [The pay-off phase of glycolysis converts 2 NAD+ to 2 NADH + 2 H+]
precursor metabolites
generated by the three central metabolic pathways. Metabolic intermediates that can be either used to make the subunits of macromolecules or oxidized to generate ATP
three central metabolic pathways
glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle (TCA cycle)
activation energy
initial energy required to break a chemical bond. Energy needed to get a reaction started
unlike human cells, some prokaryotes can use_____ as energy sources
inorganic chemicals
chemical respiration
involves chemicals and it makes ATP
The intermediates and end products of metabolic pathways are sometimes organic acids, which are weak acids. Which are predominately found inside the cell and which are predominately found outside the cell?
ionic form [pyruvate], and acid form [pyruvic acid]
until the optimal temperature is reached, raising the temperature has what effect on the speed of enzymatic reactions?
it increases their rate
oxidized
loses electrons
Glycolysis
metabolic pathway that oxidizes glucose to pyruvate, generating ATP and reducing power
anarobic respiration
metabolic process in which electrons are transferred from the electron transport chain to a terminal electron acceptor other than O2
aerobic respiration
metabolic process in which electrons are transferred from the electron transport chain to molecular oxygen (O2)
cofactor
non-protein component required for the activity of some enzymes ex:Magnesium, zinc, copper, and other trace elements
Chemoorganotrophs
obtain energy by degrading organic compounds
pay off phase of glycolysis
oxidizes and rearranges the 3-carbon molecules, generating 1 NADH and 2 ATP. Pyruvate is formed as a result
photosynthetic
pertaining to photosynthesis, the process of using the energy of light to synthesize organic compounds from CO2
consider the graph of enzyme activity vs. temperature (looks like a mountain peak that drops off quickly on far right side) in terms of the functioning of a cell, why does activity drop off so quickly after the optimal temperature is exceeded?
proteins denature and no longer function
enzymes
proteins that function as biological catalysts
Macromolecules
proteins, nucleic acids, polysaccharides, lipids
enzymes don't:
provide energy to help reactions proceed more rapidly
photophosphorylation
radiant energy
allosteric
refers to an enzyme or other protein that contains a site to which a small molecule can bind and change the protein's activity. Cells use this to adjust the activity of certain enzymes
conversion of crude oil to gasoline at a coastal refinery
relies on chemical distillation processes--not microbial metabolism
metabolic pathway
series of sequential chemical reactions that are a part of metabolism
anabolic nutrients
source of nitrogen, sulfur, etc.
potential energy
stored energy. can be stored in various forms, including chemical bonds, a rock on a hill, or water behind a dam
metabolism
sum total of all the chemical enzymatic reactions in a cell
enzyme range of conditions
temperature, pH, and salt concentration
enzyme-substrate complex-practice question
the binding of a substrate to the active site of an enzyme causes the shape of the flexible enzyme to change slightly. this induced fit results in a temporary intermediate called:
Energy
the capacity to do work. in the universe can never be created or destroyed; however, it can be changed from one form to another
hydrolysis
the chemical breakdown of a compound due to reaction with water.
active site-practice question
the critical site of an enzyme to which a substrate binds by weak forces
tricarboxylic acid cycle (TCA) (Krebs cycle, citric acid cycle)
the metabolic pathway that OXIDIZES a two carbon acetyl group to release two molecules of CO2 and generates the MOST reducing power of all the central metabolic pathways
Glycolysis-practice question
the pathway SPLITS GLUCOSE and OXIDIZES it to form two molecules of pyruvate. the pathway provides the cell with a SMALL AMOUNT OF ATP, some REDUCING power, and SIX precursor metabolites
active site
the site on the surface of an enzyme to which the substrate binds; aka the catalytic site. a relatively small crevice. critical site to which a substrate binds by weak forces
enzyme specificity
the substrate must align spatially with the active site, with few exceptions, a unique enzyme is required to catalyze each reaction in a cell, hydrogen and ionic bonding occur to induce the correct fit between substrate and active site.
Photophosphorylation
the sun's radiant energy and an electron transport chain create a proton motive force that drives the addition of P, to ADP
competitive inhibition
type of enzyme inhibitor that occurs when the inhibitor competes with the NORMAL substrate for binding to the active site. EX: sulfa drugs are used as antibacterial medications
non-competitive inhibition
type of enzyme inhibitor that results from a molecule binding to the enzyme at a site OTHER than the active site. produced by cells to regulate the activity of that cell's enzymes
it increases their rate
until the optimal temperature is reached, raising the temperature has what effect on the speed of enzymatic reactions?
rely on microbial metabolism
use of lactococcus and lactobacillus in cheese making, wine production, and production of ethanol from corn stalks sugar cane and wood for use as biofuel
cells enzymes
what part of a cell is responsible for transforming sugar to ethanol and CO2
1 glucose molecule can be made into:
2 pyruvate molecules
enzyme-substrate complex
A TEMPORARY complex formed when an enzyme binds to its substrate molecule(s). which changes its shape
6. Enzyme
A molecule, usually a protein, that functions as a catalyst, speeding up a biological reaction. more than a thousand different ones exist in a cell
substrate
AKA: REACTANTS 1. substance on which an enzyme acts to form products. 2. surface on which an organism will grow
Investment or preparatory phase of glycolysis
After the two phosphates are added, the 6-carbon sugar is then split to yield two 3-carbon molecules, each with a phosphate molecule
chemiosmotic gradient
An electrochemical gradient across the thylakoid membrane and the inner membrane of the mitochondrion; due to concentration differences of both positive charges and hydrogen ions.
13. Terminal Electron Acceptor
Chemical that is ultimately reduced as a consequence of fermentation or respiration.
Tricarboxylic Acid Cycle (TCA) (Krebs cycle, citric acid cycle)
Cyclic metabolic pathway that incorporates acetyl-CoA, ultimately generating ATP (or GTP), CO2, and reducing power
In the biosynthetic pathway shown, (starting compound-enzyme a-intermediate a-enzyme b-intermediate b-enzyme c-intermediate c- end product) which compound is most likely to serve as the allosteric inhibitor?
End product - remember, the end product generally acts as the allosteric inhibitor. This feedback inhibition allows the cell to shut down a pathway when the product begins accumulating.
1. Adenosine Triphosphate (ATP)
Generated by the three central metabolic pathways [by substrate level phosphorylation]. The energy currency of cells. Hydrolysis of the bonds between its phosphate groups can be used to power endergonic (energy-consuming) reactions. 2 molecules of ATP, net gain (4 ATP molecules are made in the pay-off phase, but 2 are spent in the investment phase of glycolysis)
5. Electron Transport Chain (ETC)
Group of membrane-embedded electron carriers (proteins) that pass electrons from one to another, and, in the process, create a proton motive force.
Non-competitive inhibition (by enzyme poisons)
Inhibitor PERMANENTLY changes the shape of the enzyme, making the enzyme non-functional. EX: Enzyme poisons such as mercury are used in certain antimicrobial compounds.
Non-competitive inhibition (by regulatory molecules)
Inhibitor changes the shape of the enzyme, so that the substrate can no longer bind the active site. This is a REVERSIBLE action that cells use to control the activity of allosteric enzymes.
2 glycolysis phases
Investment or preparatory phase and Pay-off phase
Most enzymes function best at:
Low salt concentrations and at pH values slightly above 7
10. Precursor Metabolites
Metabolic intermediates that can be either used to make the subunits of macromolecules or oxidized to generate ATP. [Five intermediates of glycolysis as well as the end product, pyruvate, are precursor metabolites used by E. coli]
Pentose Phosphate Pathway
Metabolic pathway that starts the degradation of glucose, generating reducing power in the form of NADPH, and two precursor metabolites.
7. Fermentation
Metabolic process that stops short of oxidizing glucose or other organic compounds completely, using an organic intermediate as a terminal electron acceptor.
respiration (cellular respiration)
Metabolic process that transfers electrons stripped from a chemical energy source to an electron transport chain, generating a proton motive force that is then used to synthesize ATP
4. Cellular Respiration
Metabolic process that transfers electrons stripped from a chemical energy source to an electron transport chain, generating a proton motive force that is then used to synthesize ATP.
3. Catabolism
Metabolic processes that harvest energy released during the breakdown of compounds such as glucose, using it to synthesize ATP. A set of chemical reactions that degrade compounds, releasing their energy.
2. Anabolism
Metabolic processes that synthesize and assemble the subunits of macromolecules, using energy of ATP; BIOSYNTHESIS.
biosynthesis
The process by which living organisms produce larger molecules from smaller ones. ANABOLISM
what will dramatically affect the overall energy gain of catabolism?
The step and rate at which the various intermediates are removed for biosynthesis
ATP
energy currency of the cell
2 fundamental tasks for cells to grow
They must continually SYTHESIZE NEW PARTS—such as cell walls, membranes, ribosomes, and nucleic acids—that allow the cells to enlarge and eventually divide. In addition, cells need to HARVEST ENERGY AND CONVERT IT to a form that can power the various energy-consuming reactions, including those used to make new parts.
oxidation-reduction reaction
a reaction that involves the transfer of electrons between reactants
coenzyme
a subset of cofactors, non-protein organic compounds that assist some enzymes. they act as a loosely bound carrier of small molecules or electrons. Include the electron carriers FAD, NAD+, and NADP+ (play an important role in enzyme-catalyzed oxidation-reduction reactions) some come from organic necessary vitamins
Catabolism waste products
acids, carbon, dioxide
the precursor metabolite pyruvate can be converted to any one of three amino acids:
alanine, leucine, or valine
subunits of macromolecules
amino acids, nucleotides, monosaccharides, and fatty acids
cell structures
cell wall, membrane, ribosomes, surface structures
oxidative phosphorylation
chemical energy
Endergonic
chemical reaction that requires a net input of energy because the products have more free energy than the starting compounds
identify each of the following by the most precise descriptive term as either a cofactor or coenzyme:NAD+_____, FAD______, copper____, coenzyme A_____.
coenzyme, coenzyme, cofactor, coenzyme
enzyme inhibitors
competitive and noncompetitive
Exergonic
describes a chemical reaction that releases energy because the STARTING COMPOUND have MORE free energy than the PRODUCTS. Chemical reactions that release energy because the starting compounds have more energy than the products
endergonic reaction
describes a chemical reaction that requires a net input of energy because the PRODUCTS have MORE free energy than the STARTING COMPOUND. A non-spontaneous chemical reaction in which free energy is absorbed/consumed from the surroundings.
enzymes do:
end in -ase, name reflects its function, very specific, usually act on only one or a few substrates, are not used up in the process of catalyzing reactions, and are biological catalysts.
