Microbial Metabolism Flashcards
Metabolism
The sum of the chemical reactions in an organism
Catoblistic + anabolistic reactions
Catobolism
Energy released by breaking down molecules (captured as ATP)
Anabolism
Amino acids are used to make larger more complex proteins
Which process is soley anabolic
Photosynthesis
Is glucogenesis anabolic or catabolic
anabolic
How do phtosynthesis and oxytative phsophorylation interact?
O2 produced by photosynthesis used in oxidative phosphorylation
Energy required in chemical reaction to convert reactants into products
energy of activation
How do enzymes affect chemical reactions
Increase rate
Make product production easier
What may occur after the enzyme binds to the active site
Enzyme may change shape and amino acids from active site may donate or recieve electrons
Steps of enzyme reaction
Binding to substrate active site
Formation of enzyme-substrate complex
Product formation
Dissassociation
Enzyme recovery
WHere does energy to make ATP come from in glycolysis
Glucose
Net ATP produced by one glucose in glycolysis
2
Substrate level phosphoylation
The process of moving a phosphate from metabolic products to ADP to form ATP
Oxidtative phosphorilat
Aerobic organisms use a proton gradient to drive phosphorilatoion of ADP to ATP
Kreb cycle or
Citric acid cycle
What occurs at transition/bridge step of the Kreb cycle
decarboxylation of pyruvic acid to acetyl CoA
What is the process called where NADH is converted to ATP
oxidative phosphorylation
Final electron acceptor in electron transport chain
Oxygen
What is NADH
A coenzyme
What are the main steps in cellular respiration
Glycolisis (anaerobic)
intermediate step
Krebs cycle (aerobic)
Electron Transport Chain
Which step in cellular respiration makes the most ATP?
Electron Transport
How are catabolism and anabolism related
Catabolism provides energy and building blocks for anabolism
Anabolism uses the energy and building blosk to build larger moelcules
Metabolic pathway
Sequence of enzymatically catalyzed chemical reactions in a cell
Catalyst
A substance increasing rate of chemical reaction without undergoing andy permanent chemical changes itself
Characteristiccs of a catalyst
Can be organic (enzyme) or inorganic
Almost all enzymes are proteins
How do enzymes differ from inorganic catalysts
High reaction rates (milliseconds)
Milder reaction conditions (37 degrees)
Reaction specificity
Capacity for regulation (turn on when required, turn off when not)
What is the main action of an enzyme
Lowers the activation energy of reactions
provide another path for the reaction to take that requires less energy (Bring molecules together in more efficient fashion, conserving energy)
What is an energy barrier
The amount of energy that must be overcome before a reaction can occur
(energy required to break and form bonds)
Factors affecting rate of enzyme reaction
Temperature
pH (varies, some work better in stomach vs SI)
pH is raised from stomach to SI by addition of bicarbonate from the pancreas
Substrate conc. (Until saturation point)
Enzyme conc.
Inhibitors (reduce rate at which enzyme reaction occurs)
Heavy metals
Tylonel
How do enzymes release energy
by a series of controlled reactions
How is energy as fuel molecules stored?
as chemical energy
In form of ATP, NADHm FADH
Two processes used to produce energy
Respiration and fermentation
What is oxidation
Removal of electrons from a molecule
Purpose of GLycolysis
form energy as ATP and NADH
When body requires oxygen and isnt getting enough (excersis) which pathway is used?
Glycolosis pathway
What is the opposite of respiration
Fermentation
Glycolisis pathway
ATP produced and NAD+ reduced to NADH and glucose oxidied to pyruvic acid.
Krebs cycle
Pyruvic acid converted to CoA and used in the Krebs cycle
How is ATP generated
From ADP via phosphorylation
2 ways phosphorylation occurs
Substrate level phosphorylation
Oxidative phosphorylation
Substrate level phosophrlation
Energy from molecule with high energe PO4 used to make ATP (Takes place in glycolicis and TCA (krebs) cycle)
Basically a molecule with an extra phosphate donates it’s phosphate to ADP (Enzymes act to reduce energy necessary to break the bonds and donate the phosphate)
Results in ATP and carbon skeleton chain
Oxidative Phosphorylation
Oxidations releases high energy electrons to form NADH and FADH
High energy electrons release energy in the electron transport chain
- generates proton gradient
- Proton gradient rives phosphorylation of ADP to ATP
What is carbohydrate catabolism
The way that cellular respiration releases energy by breakdown of carbs through three pathways (in presence of O2)
Where do the three respiration pathways occur in a eukaryotic cell
Glycolysis (Cytoplasm)
Krebs (Mitochondria)
Electron Transport (Mitochondria)
Which forms of cellular respiration do prokaryotic cells perform?
All three
Use compartments to carry them out
Proton gradient
The inner membrane moves high energy protons into inter membrane via intermembrane protein (given energy by the NADH) (Dam illustration) space providing energy
What drives phosphorylation of ADP to ATP?
Proton gradient
What are the products of glycolysis
2 pyruvic acid (2 C-3)
ALSO generates 2 ATP (NET GAIN)
AND 2 NADH
Why is glycolysis an incomplete oxitation?
Does not result in CO2
What product is required for the intermediate step bw Glycolysis and Krebs cycle
Pyruvic Acid
1 Glucose > 2 Pyruvic Acid > 2 Acetyl CoA
What occurs in Krebs Cycle
Acetyl CoA completely oxidized to CO2 (&NADH)
Forms some ATP in the process
Products of electron transport chain
oxidization NADH and FADH
- Electrons eventually passed to O2
Energy released used to create a pron gradient
Pron gradient drives the synthessis of ATP by chemiosmosis
chemiosmosis
as electrons flow through the elcontron transport chain, protons are pumped into inermembrane, and that gradient is used to synthesise ATP
How many ATP produced by NADH in ETC?
3
How many ATP produced by FADH2 in ETC?
2
Total ATP produced from complete oxidation of one glucose via aerobic respiration
38
How much ATP produced in the absence of O2 (from one glucose)
2 ATP (Only from glycolysis)
What is the final electron receptor in ETC?
O2
Scientific defenition of fermentation
Release of energy from oxidation organic molecules that does not require oxygen and does not use the Krebs cycle or electron transport chain (ETC)
Purpose of fermentation
Still need to produce energy when lacking oxygen
Where in the cell does fermentation take place (in the cytosol)
Characteristics of fermentation
Does not require oxygen
Does not use Krebs cycle or ETC
Does not completely break down sugars
Two major types of fermentation
ALcoholic fermentation: produces ethanol +CO2 (biproducts)
Lactic acid fermentation” Produces lactic acid
Homolactic fermentation: produces lactic acid only
Hererolactic fermentation: prodces lactic acid and other compounds
Role ATP
Captures energy from catabolic reactions to be used for anabolic reactions
Oxidation is
the loss of an electron
What is an example of a product in it’s reduced state?
formed from accepting of an electron and is considered to be in its reduced state.
Phosphorylation put simply
The addition of a phos[hate
How do each of the three systems of cellular respiration synthesize ATP?
Glycolysis: Substrate level phosphorylation
Krebs Cycle: Substrate Level Phosphorylation
ETC: Oxidative phosphorylation
Where does the final electron accepter (O2) come from in ETC?
Outside the cell
Simplify Glycolysis
oxidation of glucose to pyruvic acid with the production of some ATP and energy-containing NADH.
Simplify Krebs Cycle
oxidation of acetyl (a derivative of pyruvic acid) to carbon dioxide, with the production of some ATP, energy-containing NADH, and another reduced electron carrier, FADH2, (the reduced form of flavin adenine dinucleotide).
Simplify the electron transport chain system
NADH and are oxidized, contributing the electrons they have carried from the substrates to a “cascade” of oxidation-reduction reactions involving a series of additional electron carriers. Energy from these reactions is used to generate a considerable amount of ATP. In respiration, most of the ATP is generated in the third step.
Useful analogy for respiration mechanisms
you could imagine a stream flowing down a gentle slope during glycolysis and the Krebs cycle, supplying energy to turn two old-fashioned waterwheels. Then the stream rushes down a steep slope in the electron transport chain, supplying energy for a large modern power plant. In a similar way, glycolysis and the Krebs cycle generate a small amount of ATP and also supply the electrons that generate a great deal of ATP at the electron transport chain stage.
What is different about fermentation compared to respiration
Both begin with glycolysis, however, fermentation uses the subsequent pyruvic acid which is converted into one or more different products, depending on the type of cell.
These products might include alcohol (ethanol) and lactic acid. Unlike respiration, there is no Krebs cycle or electron transport chain in fermentation. Accordingly, the ATP yield, which comes only from glycolysis, is much lower.
Does Glycolysis require O2
No
Net production of ATP from Glycolysis
2 ATP
What else occurs in Glycolysis other than ATP production
NAD is reduced to NADH
How many ATP are involved in Glycolysis
2 to get it started, produces 4
What does the intermediate step exist to do?
Convert pyruvic acid to acetyl CoA ad CO2 via oxidization
Primary function of Krebs cycle
Acetyl CoA completely oxidized to CO2 (and NADH)
Where is the ETC located in prokaryotess vs eukaryotes
Inner cell membrane for pros
Inner mitochondrial membrane for euks
Why wouldn’t FAD and NAD appear in a reaction equation?
because all of the NAD+ and FAD that enter into the reactions are oxidized back to their original form when they give up their electrons.
How many turns does it take the Kreb cycle to process pyruvic acid?
t takes two “turns” of the Krebs cycle to process the pyruvic acid molecules resulting from the glycolysis of one glucose molecule.
What enables the cyclical nature of the krebs cycle
The oxaloacetic acid that accepts the acetyl group is regenerated
A toxin that causes a leak to form in the inner mitochondrial membrane such that protons could bypass the ATP synthase would prevent
oxidative phosphorylation.
Final electron recepotr for cellular respiriation is always
O2
