Microbiology Chapter 5
ATP generation in Fermentation
1. generated by oxidation of ORGANIC molecules. 2. Anerobic, but may occur in the presence of oxygen. 3. Final electron acceptor is organic. 4. ATP production is accomplished by substrate level phosporylation. Does not use Krebs or electron transport chain. 5. Only 1 or 2 ATP is made per molecule of starting material. Much of the original energy remains stored in the chemical bonds because the substrate is not completely oxidized/ broken down. The purpose of fermentation is to reduce pyruvic acid and to oxidize NADH to NAD+, which is used again in glycolysis with another glucose molecule. In lactic acid fermentation, Electrons are removed from NADH+ and put onto pyruvate, making it lactic acid. Similar for alcohol fermentation.
How many NAHD molecules and FADH2 are made by aerobic respiration
10 and 2
How many ATPs are made during the Krebs cycle
2
each FADH2 can generate how many ATPs of energy
2
How many ATPs are made during glycolysis
2 net, 4 gross
how many ATP, NADH, AND FADH2 does Krebs cycle produce
2,8,2
each NADH can generate how many ATPs of energy
3
how many ATP does the ETC produce
34
how many molecules of ATP are made from the electron transport chain
34
How much ATP do eukaryotes generate?
36 ATP. Some energy is lost when electrons are shuttled across the mitochondrial membrane.
How much ATP do prokaryotes generate?
38
what is the maximum number of ATP molecules that can be produced from each glucose molecule in prokaryotes
38
exogonic reaction
A chemical reaction that releases energy
endergonic reaction
A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings.
allosteric site
A specific receptor site on some part of an enzyme molecule that is not the active site. Noncompetitive inhibitors can bind at allosteric site, causing the shape of the active site to change to not be able to accept the substrate and making it nonfunctional.
enzyme-substrate complex
A temporary complex formed when an enzyme binds to its substrate molecule(s).
Ribozymes
A unique type of RNA with enzymatic activity even though it is not a protein, it is a nucleic acid. Acts as a catalyst to cut and splice strands of RNA molecules.
Energy in ATP
ATP has high energy bonds. Energy stored in the unstable bonds is released quickly and easily, although the amount of energy stored is not exceptionally large. The unstable bonds of ATP provide the cell with readily available energy.
ATP generation
ATP is produced by attaching a phosphate ion to ADP. This reaction stores energy in its bonds. Phosphorylation.
ADP
Adenosine diphosphate
Entner-Doudoroff pathway
An alternate pathway for the oxidation of glucose to pyruvic acid in bacteria that have the enzymes for this pathway. Produces NADPH and ATP Does not involve glycolysis Most common in gram negative bacteria Pseudomonas, Rhizobium, Agrobacterium
The final electron acceptor in anerobic respiration is
An inorganic molecule other than Oxygen
Enzyme components
Apoenzyme+ coenzyme= haloenzyme
cellular respiration equation
C6H12O6 + 6O2 --> 6 CO2 + 6 H2O + ATP
what gas is a waste product in the Krebs cycle
CO2
Autotrophs
Carbon source is CO2. Photoautotrophs- Light is energy source. Use oxygenic photosynthesis as in plants, algae, or cyanobacteria, or anoxygenic photosynthesis as in green and purple algae. Chemautotrophs- Chemicals are energy source.
Denatured
Change in the molecular structure of a protein, usually making in non functional. enzymes can be denaturated by temp and pH and lose their tertiary structure. Involves the breakage of hydrogen bonds and other noncolvalent bonds. Also can be denatured by acids, bases, heavy-metal ions, alcohol, and UV radiation.
Vitamin B2 (Riboflavin)
Component of coenzymes FAD and FMN, so needed for electron transport chain
The chemical categories of the Krebs cycle
Decarboxylation- removal of carbons. Oxidation-reduction- removal and gaining of elrons and hydrogens
What happens to enzymes at high temps?
Denaturation (unravel), lose their catalytic properties.
saturated
Enzymes working at maximum rate and the active site is always occupied by substrate or product molecules. At a certain point no more enzymes are available to react, so rate of reaction stays constant.
Lipase
Exoenzyme that break down lipids to fatty acids and glycerol. Glycerol to dehydroxyacetone phosphate to G3P to glycolysis to pyruvic acid to krebs. Fatty acid to beta oxidation of fatty acid to AcetylCoA to krebs.
Protease
Exoenzyme that digests protein to amino acids, to be oxidized to be sent to glycolysis, krebs, and ETC. Protein to Amino acid to deamination, decarboxylation, dehydrogenationa and desulfurization tp make organic acids to be sent to krebs.
name the two major stages of aerobic respiration
Krebs cycle and etc
where does aerobic respiration take place in prokaryots
Krebs cycle-cytosol etc-cell membrane
pathways associated with FAD
Krebs, etc
pathways associated with NADH
Krebs, glycolysis, etc, fermentation
intermediate cycle
Links Krebs to glycolysis. Each pyruvic acid is converted to acetyl CoA, and a CO2 and a NADH and produced. Pyruvic Acid enters membrane and enzymes remove a CO2. The molecule gets altered/oxidized and NAD+ gets the electrons, so is reduced to NADH. A 2 carbon Acetyl group is left, and is attached to Coenzyme A, producing acetyl CoA. The chemical bonds of the acetyl group are full of potential energy that will be used to make ATP, NADH and FADH2 during the Krebs cycle.
amphibolic pathways
Metabolic pathways that function in both anabolism and catabolism. For example, Krebs cycle catabolises carbohydrates and some of the products can be used for the anabolic synthesis of amino acid precursors. Dual purpose, bridge between reactions that lead to catabolism and anabolism.
two carriers are reduced in the Krebs cycle..what are they?
NAD+ ---NADH and FAD-----FADH2
Important coenzymes
NAD+, NADP, FAD, CoA
Vitamin B3
Niacin. Part of NAD molecule; active in electron transfers.
aerobic respiration requires what gas?
O2
Chemotrophs
Obtain energy from oxidation of organic compounds. Chemoheterotrophs use organic compounds as energy source. If Oxygen is final electron acceptor, use aerobic respiration as in animals and most fungi, protozoa and bacteria. If final electron acceptor is organic compound, fermentation occurs. Commonly pyruvate accepts electron/gets reduced as NADH gets oxidized to NAD+ so NAD+ can go back to let glycolysis continue. If final electron acceptor is not inorganic compound, the anaerobic respiration uses alternative electron transport chain Chemautotrophs oxidize inorganic compounds to store energy in ATP via oxidative phosphorylation.
Why is anerobic metabolism less favorable than aerobic metabolism?
Only part of the Krebs cycle operates under anerobic conditions, and because not all of the carriers in the electron transport chain participate in anerobic respiration, so anerobes grow more slowly than anerobes
Heterotrophs
Organic compounds are carbon source. Photoheterotrophs- Light is energy source, as in green and purple nonsulphur bacteria. Chemoheterotrophs- chemicals are energy source. Can use aerobic respiration, fermentation, or anaerobic respiration.
Redox reaction
Oxidation and reduction occur simultaneously. Wherever electrons go, they bring energy.
Oxidation
Oxidation is is loss. Removal of electrons from a substrate, removal of hydrogens (dehydrogenation) *wherever electrons go, hydrogens will follow. NAD+ = oxidized form
Where is most of the cells energy produced from?
Oxidation of carbohydrates
what gas serves as the final acceptor of electrons in the aerobic ETC?
Oxygen
The final electron acceptor in aerobic respiration is
Oxygen, producing water when the H's that are present also attach.
Final electron acceptor in aerobic cellular respiration
Oxygen. Makes 38 total ATP in prokaryotes.
chemiosmosis
Process by which a Hydrogen pump pumps protons into a space to create a high concentration. H+ passively flows through the ATP synthase which leads to the creation of ATP. H+ protons diffuse because of the chemical and electrical gradient.
Photophosphorylation
Production of the ATP in a series of redox reactions in photosynthetic cells; electrons from chlorophyll initiate the reactions. Light causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll thru a system of carrier molecules is used to generate ATP. Light energy is converted to chemical energy of ATP and NADPH which are then used to synthesize organic molecules.
Pentose Phosphate Pathway
Provides a way to break down 5 carbon sugar/ pentose. Makes 1 ATP. Primary role is production precursor metabolites, NADPH. Operates along with glycolysis.
Reduction
Reduction is gain. Gain of electrons of a substrate, gain of hydrogens (hydrogenation). NADH = reduced form
Catabolic reactions in metabolism
Release energy by oxidation of molecules. Provides the building blocks for anabolic reactions. Often involves hydrolysis reactions as a water molecule is pulled apart and stuck onto the now separate molecules. Splitting a Pi from an ATP to make ADP + Pi and energy. Exogonic because they release energy from chemical bonds and produce more energy than it uses. Fermentation, cellular aerobic respiration, anaerobic respiration
Two major types of glucose catabolism
Respiraion- glucose completely broken down Fermentation- glucose partially broken down
When a cell oxidizes a molecule of glucose C6H12O6 to H20 and CO2...
The energy in the glucose molecule is removed stepwiseand ultimately trapped by ATP, which can then serve as an energy source for energy-requiring reactions.
Substrate level phosphorylation
The formation of ATP by directly transferring a high energy inorganic phosphate group to ADP. Generally the inorganic phosphate group has acquired its energy during an earlier reaction in which the substrate itself was oxidized. Glycolysis and krebs
Reduction is
The gain of electrons by a substance involved in a redox reaction; always accompanies oxidation. The charge is reduced because electrons have a negative charge.
Area where H+ protons are concentrated for electron transport chain in gram positive bacteria
The granular layer, between the cell wall and the cell membrane
Oxidation is
The loss of electrons from a substance involved in a redox reaction. The charge is increased because electrons have a negative charge Because most biological oxidations involve the loss of hydrogen atoms, they are also called dehydogenation reactions. For example, when an organic molecule is oxidized by the loss of two hydrogen atoms and a molecule of NAD+ is reduced to NADH. Cells use them in catabolism to extract energy from nutrient molecules.
Glycolysis
The oxidation of glycose to pyruvic acid with production of some ATP and energy-containing NADH. Glucose is broken down and oxidized. Its energy is taken and used down the line in the metabolic pathway. Other molecules get the energy and are reduced. most common pathway for oxidation of glucose. Pyruvic acid is the end product. 2 Net ATP and 2 NADH molecules are produced from one glucose molecule.
Area where H+ protons are concentrated for electron transport chain in gram negative bacteria
The periplasmic space
proton motive force
The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis.
The most important products of Krebs cycle
The reduced coenzymes NADH and FADH2 because they contain most of the energy originally stored in glucose.
What is the point of the Krebs Cycle?
To make highly reduced molecules with energized electrons so they can be sent to the electron transport chain. The link step before the cycle makes 2 NADH and 2 CO2 in total. Each Krebs cycle proper makes 1 ATP, 3 NADH and 1 FADH2, and also 4 CO2. The cycle runs 2 times per 1 glucose molecule, so it makes 2 ATP, 6 NADH, and 2 FADH2.
Function of fermentation
To regenerate NAD+ from NADH made in glycolysis in anaerobic conditions to allow continuation of glycolysis. It uses pyruvate as the acceptor of the high energy electrons from NADH, therefore reducing pyruvate to ethanol or lactate. Electrons are tranferred along with protons from reduced coenzymes NADH or NADPH to pyruvic acid or its derrivatives. Those final electron acceptors are reduced to various end-products. The function is to ensure a steady supply of NAD+ and NADP+ so that glycolysis can continue. In fermentation, ATP is generated only during glycolysis.
Goal of Electron Transport Chain
To release energy as electrons are transferred from from higher-energy compounds to lower energy compounds. The energy that is released is used to create a concentration gradient of protons H+ outside of the plasma membrane. Energy is released every time an e- is transferred, and used to pump H+ out of the membrane against its concentration gradient. The plasma membrane is impermeable to protons, so the concentration gradient is maintained and the proton pumps use active transport.
True or False: a complex can be a substrate for more than one enzyme?
True, so the fate of a compound depends on the enzyme that acts on it.
Anabolic reactions in metabolism
Uses energy to synthesize macromolecules that make up a cell. Endergonic because storing energy in the chemical bonds and they use more energy than they produce. Amino acids into proteins. Photosynthesis.
Panothenic acid
Vitamin B5. Part of coenzyme A for oxidazing pyruvate in the citric acid cycle.
Energy is released step by step because
a series of redox reactions is more controlled, so heat damage is minimized (affecting cell and protein structure/denaturing) and energy and chemicals are conserved for efficient use and storage. The purpose of metabolic pathways is to to release and store energy from organic molecules by a series of controlled reactions rather than a single burst.
Non competitive inhibition
acts on other parts of the apoenzyme or cofactor and decreases the enzymes ability to combine with the normal substrate
ATP
adenosine triphosphate, main energy source that cells use for most of their work
Organic cofactors
aka coenzymes- derived from vitamins. They alter the shape of the enzyme to make it functional.
what type of organisms perform glycolysis
all life on earth
constitutive enzymes
always present, always produced in equal amounts or at equal rates, regardless of the amount of substrate
what is the proton motive force
an electromechanical gradient formed across a membrane
what organisms trap sunlight and store it in carbohydrates
autotrophs
how does a coenzyme assist an enzyme
by accepting or donating matter. Makes the enzyme active by changing the shape to be right for a reaction with the substrate to occur.
Inhibition
chemicals that can stop the function of an enzyme
organisms that use CO2 as a carbon source and energy source such as ammonia or hydrogen sulfide are called
chemoautotrophs.
The first product of the Krebs cycle is
citric acid
Competitive inhibition
competing with normal substrate for the active site of the enzyme
what are the steps of the Krebs cycle?
conversion of pyruvate to acetyl CoA and the Krebs cycle proper
define the Krebs cycle
converts acetyl CoA into NADH, FADH2, CO2, and ATP. The oxidation/ breakdown or removal of high energy electrons from acetyl CoA to carbon dioxide, with the production of some ATP, energy containing, reduced electron carriers NADH and FADH2.
where does Krebs cycle occur in prok
cytoplasm
where does anaerobic respiration occur
cytoplasm
where does glycolysis happen in euks and proks
cytoplasm
which part of the cell does fermentation occur
cytosol
Six classes of enzymes
defined on the basis of the types of reactions they catalyze. Oxidoreductase, Transferase, Hydrolayse- Catabolic, Lyase- Catabolic, Isomerase, Ligase- Anabolic,
Inorganic cofactors
derived from minerals or trace elements. needed to make some enzymes work. Minerals have a charge that alters the shape of the enzyme to make it functional.
what is the last step in the ETC
electrons are transferred to O2
Feedback inhibition
end product inhibits an enzyme near the start of the pathway. Stops the cell from making more of a substance than it needs and wasting chemical resources in the process. The final product is often a non-competitive inhibitor with the first enzyme in the metabolic pathway..
Anabolism
energy USING process to build complex molecules from simpler ones. Often involve dehydration synthesis or releasing of water.
Mechanism of enzymatic action
enzyme+substrate--->enzyme substrate complex-----substrate is affected----->leaves the enzyme
what are made by yeasts during alcoholic fermentation
enzymes
what is the fermentation end product for saccharomyces
ethanol and CO2
what alcohol is made in alcoholic fermentation
ethyl alchohol
Reaction rate
frequency of collisions with enough energy to bring about a reaction. can be increased by enzymes or by increasing temp or pressure. turnover rate is generally 1-10,000 molecules per second
ATP generation in cellular respiration
generated by oxidation of electron carriers, passage of E down the ETC, and chemiosmosis. Final electron acceptor is oxygen (aerobes)or inorganic compound (Anaerobes). Fermentation does not use ETC. The organic molecule Pyruvate gets reduced as NADH gets oxidized to allow NAD+ to be free to act in glycolysis.
ATP generation in photosythesis
generated by photophosporyization
Enzymes
globular, 3D proteins produced by living cells. biological catalysts. specific for a chemical reaction. help start or speed up the reaction by lowering activation energy. particular for a certain substrate/shape driven
What is the most commonly used carb?
glucose
which one molecule could provide the carbon , energy, and electron source for chemoheterotrophs
glucose
In fermentation, ATP is generated only in what metabolic pathway
glycolysis
what process begins cellular respiration
glycolysis
what are the pathways of aerobic respiration
glycolysis, Krebs cycle, etc
Hydrolase enzymes
hydrolysis-addition of water splits chemical bonds by addition of water. Catabolic.
what effect does lactid acid have on muscle cells
it causes fatigue and cramps- acidity increases so soreness increases
Ligase enzymes
joining of molecules- using energy usually derived from the breakdown of ATP. Forms a chemical bond between two atoms. Anabolic.
What is the fermentation end product for streptococcus, lactobacillus, and bacillus
lactic acid
Name two types of fermentation
lactic acid and alchol
where does Krebs cycle occur in euk
mitochondria
where does ETC occur in eukaryotes
mitochondrial inner membrane
Final electron acceptor in anaerobic respiration
not Oxygen- another inorganic molecule. Makes 2-38 ATP total in prokaryotes using glycolys, parts of krebs, and an alternative ETC that does not use oxygen as final electron acceptor.
Phototrophs
obtain energy from light Photoheterotrophs get their carbon source from organic compounds. Green and purple nonsulphur bacteria. Photoautotrophs use CO2 as their carbon source. Oyxgenic photosynthesis for plants, algae, and cyanobacteria to produce oxygen. Anoxygenic photosynthesis for green and purple bacteria does not produce oxygen.
Oxidoreductase enzymes
oxidation reduction, in which oxygen and hydrogen is gained or lost catalyzes redox reactions
If there is no oxygen in cells, the products of glycolysis enter _________pathways that yield no __________.
oxygen, ATP
what are the requirements for generation of ATP by chemiosmosis
passage of electrons through ETC, formation of protein motive force, active transport of protons across a phosoloid membrane. use of proton flow by ATP synthase
NADPH is used in
photosynthesis
where does ETC occur in prokaryotes
plasma membrane
where does chemiosmosis occur in prok?
plasma membrane
source of energy for electron transport chain
proton motive force
What is acetyl CoA and to what does it combine
pyruvic acid + CoA; oxaloacetic acid
What happens to enzymes at low temps?
reaction rate decreases
Isomerase
rearrangement of atoms within a molecule (neither catabolic or anabolic)
Lyase enzymes
removal of atoms without hydrolysis. splits chemical bonds without water. Catabolic.
Metabolic pathway
sequence of enzymatically catalyzed chemical reactions in a cell; regulated by enzymes. Store energy in and release energy from organic compounds.
Electron transport chain
series of molecules in a membrane that pick up E from carrier molecules (NADH AND FADH2) , pass the electrons down the line in a series of redox reactions, and use the energy released from the electrons to pump protons across the membrane in which they are embedded.
Collision theory
states that chemical reactions can occur when atoms, ions, and molecules collide at 1. the right speed, and 2. in the right position
glycolysis produces ATP through what type of phosphorylation?
substrate level phosphorilation
Oxidative Phosphorylation
synthesis of ATP as a result of electron transport from NADH or FADH2 to O2 by a series of electron carriers. In Eukaryotes, occurs in mitochondria. In prokaryotes, occurs in cell membrane.
carbon fixation
synthesis of sugars by using carbon atoms from CO2
Phosphorylation
the addition of a phosphate group to an organic molecule. ATP is generated by the phosphorylation of ADP in 3 ways. 1. substrate level phosphorylation, as in glycolysis and krebs 2. oxidative phosphorylation, as in ETC. 3. photophosphorylation.
Catabolism
the energy RELEASING process; decomposition reactions. Provides the building blocks and energy for anabolism
Activation energy
the minimum energy required so the reaction will occur
Optimum pH
the pH at which enzymatic activity is maximal
Metabolism
the sum of the chemical reactions in an organism, including catabolic and anabolic reactions.
why are enzymes important in living organisms?
they bring together reactants or properly orient a molecule for reaction, lowing activation energy
Transferase enzymes
transfer of functional groups, such as an amino group, acetyl group, or phosphate group catalyzes transfer of functional groups
Chemiosmosis
uses proton gradient across cytoplasmic membrane to generate ATP when protons move down their concentration gradient through ATP synthase
Inducible enzymes
usually function in catabolic pathways; their synthesis is induced by a chemical signal
when is fermentation used?
when you're out of electron acceptors
