Exam II Flashcards
Briefly define metabolism
Metabolism is the sum of all chemical reactions within an organism.
Briefly define metabolic pathway
A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions that occur in a cell. The metabolism of a cell is composed of many metabolic pathways.
What is the sum of all chemical reactions within an organism called?
Metabolism
What is a sequence of enzymatically catalyzed chemical reactions that occur in a cell?
Metabolic pathways
The metabolism of a cell is composed of many different what?
Metabolic pathways
What are enzymatically catalyzed chemical reactions of a cell called?
Metabolic pathways
What is anabolism?
Anabolism consists of enzyme-regulated chemical reactions that require the input of energy. Anabolism generally results in smaller of simpler organic molecules being built into larger or more complex molecules.
What consists of enzyme-regulated chemical reactions that require the input of energy?
Anabolism
What type of metabolism generally results in smaller of simpler organic molecules being built into larger or more complex molecules?
Anabolism
Anabolism generally results in:
1) smaller or
2) larger organic molecules
being built into larger or more complex molecules?
Smaller
Anabolism results in which one:
1) larger or more complex molecules or
2) smaller or simpler molecules
Larger
Briefly define catabolism.
Catabolism consists of enzyme-regulated chemical reactions that release energy. Catabolism generally results in larger, more complex molecules being converted or broken down into smaller or simpler molecules.
What type of metabolism consists of enzyme-regulated chemical reactions that release energy?
Catabolism
What type of metabolism generally results in larger, more complex molecules being converted or broken down into smaller or simpler molecules?
Catabolism
Does catabolism begin with larger or smaller molecules that are being converted as compared to anabolism?
Larger
Catabolism results in the creation of smaller or larger molecules than anabolism?
Smaller
Catabolism results in which one:
1) larger or more complex molecules or
2) smaller or simpler molecules
Smaller or simpler molecules
What is an enzyme?
Enzymes are proteins that are capable of catalyzing chemical reactions.
An enzyme has a specific pocket or surface that allows it to bind to a surface. What is this specific pocket called?
The active site
What is the quality that allows an enzyme’s active site to specifically bind to specific substrate?
Same shape
What is the name of the substance that binds to the active site on an enzyme?
Substrate
What is a substrate?
The substance that is able to bind to an enzyme.
What must bind to the enzyme to form a complex before the enzyme will be able to catalyze the reaction?
The substrate
What does the binding of the enzyme and substrate called?
Enzyme-substrate complex
What occurs first:
1) The enzyme catalyzes the reaction with the enzyme-substrate complex or
2) The substrate binds with the enzyme to form the enzyme-substrate complex?
2) The substrate binds with the enzyme to form the enzyme-substrate complex.
What must happen before an enzyme will be able to catalyze the reaction that converts the substrate into the product?
The substrate must bind to the enzyme
What is the result called when an enzyme-substrate complex is catalyzed?
The product
What is the name of the end result of an enzyme-substrate complex that has been catalyzed?
The product
Enzyme + substrate + reaction = what
The product
Define the product of an enzymatic reaction?
The result of the substrate binding to the enzyme to form the enzyme-substrate complex that is than catalyzed.
Conversion of the substrate into the product in an enzymatic process requires which of the following:
1) an enzyme
2) binding of the substrate to the enzyme
3) a substrate
All three:
1) an enzyme
2) binding of the substrate to the enzyme
3) a substrate
What is the binding of an enzyme to the active site sometimes called?
Lock and key fit
What does “lock and key” refer to in the topic of enzymes?
It refers to the fit between the substrate and the active site on an enzyme.
Each substrate will fit into different shaped active sites on enzymes or specifically-shaped active sites?
Specifically shaped
True/False
Each substrate will fit a specific enzyme in a way like each key fits a specific lock.
True
True/False
Some substrates cause parts of the active site of the enzyme to move.
True, it’s called the “induced fit model.”
Why do some substrates, like in the induced fit model, cause parts of the active site of an enzyme to move?
To allow a tighter fit between the enzyme and substrate.
What do some substrates do to allow a tighter fit with an enzyme?
They cause parts of the active site on an enzyme to move (called the induced fit model).
Describe the steps in an enzymatic reaction.
- Substrate enters active site; enzyme changes shape such that its active site enfolds the substrate (induced fit).
- Substrates held in active site by weak interactions such as hydrogen bonds and ionic bonds.
- Active site can lower EA and speed up a reaction.
- Substrates are converted to products.
- Products are released.
- Active site is available for two new substrate molecules.
7.
What does EA mean in an qnzymatic reaction?
Activation energy
What does ∆G mean?
Gibbs free energy, which is the amount of energy required for or released by a reaction, which is the difference in the chemical energy of the starting molecule (the substrate) from the product.
How do enzymes affect ∆G?
Enzymes do not affect ∆G.
How do enzymes affect the activation energy of a chemical reaction?
Enzymes and other catalysts allow chemical reactions to occur more quickly or more often by lowering the activation energy required for the chemical reaction.
What catalyst lowers the activation energy required for a chemical reaction?
An enzyme
What is the substance called that lowers activation energy?
A catalyst. Enzymes are catalysts.
Can a chemical reaction occur without an enzyme and why?
Yes, a chemical reaction could occur without an enzyme but enzymes lower the activation energy of the reaction.
How do competitive and non-competitive inhibitors inhibit the action of enzymes?
What is an inhibitor?
Small molecules that prevent enzymes from catalyzing chemical reactions.
Why do cells use inhibitors?
Inhibitors control chemical reactions, making specific inhibitors to turn off specific chemical reactions.
What do cells use to control chemical reactions or to turn off specific reactions?
Inhibitors
What are competitive inhibitors?
Inhibitors that bind to the active site of a specific enzyme and prevent the substrate from binding.
What binds to the active site of a specific enzyme and prevents the substrate from binding?
Competitive inhibitors
What binds directly to the active site on an enzyme and directly competes for binding with the substrate?
A competitive inhibitor
What is a non-competitive inhibitor?
A non-competitive inhibitor binds to a part of the enzyme other than the active site, referred to as an allosteric site. By binding to the allosteric site, the non-competitive inhibitor causes a change in the shape of the enzyme, most importantly in the active site, which prevents the substrate from binding to the distorted active site.
What binds to the active site of a specific enzyme and prevents the substrate from binding?
A competitive inhibitor
A non-competitive inhibitor binds to a part of the enzyme other than the active site, referred to as what?
The allosteric site
What part of the enzyme does a non-compeitive inhibitor bind to?
The allosteric site.
What is an allosteric site?
The site on an enzyme that a non-compeitive inhibitor binds to.
What do a competitive inhibitor and a non-competitive inhibitor have in common?
They both prevent a substrate from binding to the active site, therefore preventing the enzyme-substrate complex from forming and will not be able to catalize the reaction and form products.
What two substrances prevent an enzyme-substrate complex from forming?
A competive inhibitor and a non-competitive inhibitor.
What happens when a non-competitive inhibitor binds with the allosteric site on an enzyme?
The non-competitive inhibitor causes a change in the shape of the enzyme, most importantly the active site, which prevents the substrate from binding to the distorted active site.
What can bind to the allosteric site on an enzyme and cause the enzyme to distort?
A non-competitive inhibitor
What is ATP short for?
Adenosine triphosphate
What type of molecule is adenosine triphosphate?
One of the nucleotides used to make RNA.
What is ATP used for?
Used by cells to store chemical energy in a readily-accessible format.
What is adenosine triphosphate used for?
Used by cells to store chemical energy in a readily-accessible format (stores energy, acts like a rechargable battery).
Where is energy stored in an ATP molecule?
ATP has three phosphate groups joined in a chain and the covalent bonds that join these phosphate groups contain a relatively large amount of chemical energy.
How is energy stored in ATP?
ATP has three phosphate groups joined in a chain and the covalent bonds that join these phosphate groups contain a relatively large amount of chemical energy.
Give three examples of enzymes.
- ATP synthase
- Catalase
- DNA polymerase
What are
- ATP synthase
- Catalase
- DNA polymerase
Enzymes
What is ATP synthase?
An enzyme
What is catalase?
An enzyme
What is DNA polymerase?
An enzyme
What is the structure of ATP?
Adenine, ribose sugar and three phosphate groups joined in a chain.
What are the bonds in which ATP stores energy?
The covalent bonds that join the three phosphate groups in a chain contain a relatively large amount of chemical energy.
What is the type of energy stored in the covalent bonds of ATP?
Chemical energy
How is ATP converted to ADP?
Breaking one of the bonds converts ATP (adenosine triphosphate) to ADP (adenosine diphosphate) and Pi (an inorganic phosphate) and releases chemical energy.
Breaking one of the bonds leads to a release of chemical energy in cellular metabolism and the conversion of what to what?
Converting ATP to ADP
What is the formula for the hydrolysis of ATP?
ATP + H2O = ADP + Pi (inorganic phosphate) + energy
Cells can capture chemical energy by using it to convert ADP and Pi to what?
ATP
What happens to the cell when ADP + Pi is converted to ATP?
Energy is captured
What happens in catabolic pathways to energy and ATP?
- Energy is used to make ATP
- Will have a gain of ATP
Energy is used to make ATP and the cell will have a gain of ATP in what pathway?
Catabolic pathways
What happens in anabolic pathways to energy and ATP?
- Energy is supplied as ATP
- Will have a loss of ATP (Anabolic pathways require energy)
True/False
Catabolic reactions transfer energy from complex molecules to ATP?
True. Catabolic reactions break down larger molecules, such as carbohydrates, lipids, and proteins from ingested food, into smaller molecules.
Catabolic reactions also breakdown complex molecules to ATP.
True/False
Anabolic reactions transfer energy from ATP to complex molecules.
True. Anabolic reactions synthesize larger molecules from smaller ones, using ATP as the energy source for these reactions.
Are electrons lost or gained in oxidation reactions?
Electrons are lost
When electrons are lost in a reaction, what type is this?
Oxidation
Oxidation reactions involve the loss/gain of electrons?
Loss of electrons
What’s it called when electrons are gained in a chemical reaction?
Reduction reaction
What is a reduction reaction?
A chemical reaction whereby electrons are gained
In a reduction reactions, what happens to electrons?
Electrons are gained
What’s the difference between a reduction and an oxidation reaction?
In a reduction reaction, electrons are gained.
In an oxidation reactions, electrons are lost.
In a(n) ________ reactions, electrons are lost.
In a(n) _________ reaction, electrons are gained.
In a(n) oxidation reactions, electrons are lost.
In a(n) reduction reaction, electrons are gained.
Since electrons cannot be created or destroyed, what will always be linked to an oxidation reaction?
A reduction reaction
An oxidation reaction will always be linked to what other type of reaction?
A reduction reaction
Why are reduction and oxidation reactions always linked?
Because you can neither create nor destroy electrons.
Generally, with organic molecules, this type of reaction will lead to a gain of oxygen atoms and a loss of hydrogen atoms.
Oxidation
Oxidation reactions lead to a loss or gain of oxygen atoms and a loss or gain of hydrogen atoms.
Oxidation reactions lead to a gain of oxygen atoms and a loss of hydrogen atoms.
A molecule that is oxidized, could end up with more _____ atoms and fewer _____ atoms than when it started.
Oxygen, hydrogen
A molecule that is reduced, could end up with loss of _____ atoms and a gain of _____ atoms than when it started.
Oxygen, hydrogen
Oxygen and hydrogen atoms are lost or gained in a reduction reaction?
Hydrogen gained, oxygen lost
Describe the role of electron carriers in the cell.
Electron carriers are molecules that are used to transfer (relatively high energy) electrons between metabolic pathways.
Reactions involving electron carriers will always be oxidation-reduction reactions.
Electron carriers are molecules that will always transfer electrons by what type of reactions?
Oxidation-reduction reactions
Oxidation-reduction reactions are indicative of what type of carriers that transfer electrons in metabolism?
Electron carriers
What is transferred using NAD+, FAD and NADP+ in metabolism?
Electrons
If the electron carrier is oxidized over the course of a reaction, another molecule in the reaction will be ____________.
Reduced
If the electron carrier is reduced over the course of a reaction, another molecule in the reaction will be ____________.
Oxidized
What type of reactions do electron carriers use to transfer electrons?
Oxidation-reduction reactions
Name the oxidized forms of three electron carriers involved in metabolism.
NAD+ (reduced to NADH)
FAD (reduced to FADH2)
NADP+ (reduced to NADPH)
(Note: Each electron carrier will pick up or donate 2 electrons)
Name the reduced forms of the three electron carriers involved in metabolism.
NADH (oxidized to NAD+ + H+)
FADH2 (oxidized to FAD + 2H+)
NADPH (oxidized to NADP+ + H+)
(Note: Each electron carrier will pick up or donate 2 electrons)
NADH is the oxidized or reduced form of NAD+ + H+?
Reduced
FAD + 2H+ is the oxidized or reduced form of FADH2?
Oxidized
NADPH is the oxidized or reduced form of NADP+ + H+?
Reduced
NAD+ + H+ is the oxidized or reduced form of NADH?
Oxidized
FAD + 2H+ is the oxidized or reduced form of FADH2?
Oxidized
NADP+ + H+ is the oxidized or reduced form of NADPH?
Oxidized
In oxidation-reduction reactions with electron carriers, how many electrons are picked up or donated?
2 electrons:
NAD+ + H+ = NADH
FAD + 2H+ = FADH2
NADP+ + H+ = NADPH
In oxidation reactions involving electron carriers, are two electrons picked up or donated?
Donated
In reduction reactions involving electron carriers, are two electrons picked up or donated?
Picked up
True/False
NADH is oxidized to NAD+ + H+
FADH2 is reduced to FAD + 2H+
NADPH is oxidized to NADP+ + H+
True
False
True
True/False
NAD+ + H+ is reduced to NADH
FADH2 is oxidized to FAD + 2H+
NADP+ + H+ is reduced to NADPH
True
True
True
Describe the energy requirements and carbon requirements of chemoheterotrophs.
Chemoheterotrophs.
Prefixes that describe chemical requirements:
- Chemo - must use oxidation-reduction reactions to obtain chemical energy
- Photo - can use light to obtain chemical energy (may also be able to use oxidation-reduction reactions)
Prefixes that describe carbon requirements:
- Hetero - must use larger organic molecules as the starting point for anabolism
- Auto - can use CO2 as the starting point for anabolism (may also be able to use larger organic molecules)
Describe the energy requirements and carbon requirements of chemoautotrophs.
Chemoautotrophs.
Prefixes that describe chemical requirements:
- Chemo - must use oxidation-reduction reactions to obtain chemical energy
- Photo - can use light to obtain chemical energy (may also be able to use oxidation-reduction reactions)
Prefixes that describe carbon requirements:
- Hetero - must use larger organic molecules as the starting point for anabolism
- Auto - can use CO2 as the starting point for anabolism (may also be able to use larger organic molecules)
Describe the energy requirements and carbon requirements of photoheterotrophs.
Photoheterotrophs.
Prefixes that describe chemical requirements:
- Chemo - must use oxidation-reduction reactions to obtain chemical energy
- Photo - can use light to obtain chemical energy (may also be able to use oxidation-reduction reactions)
Prefixes that describe carbon requirements:
- Hetero - must use larger organic molecules as the starting point for anabolism
- Auto - can use CO2 as the starting point for anabolism (may also be able to use larger organic molecules)
Describe the energy requirements and carbon requirements of photoautotrophs.
Photoautotrophs.
Prefixes that describe chemical requirements:
- Chemo - must use oxidation-reduction reactions to obtain chemical energy
- Photo - can use light to obtain chemical energy (may also be able to use oxidation-reduction reactions)
Prefixes that describe carbon requirements:
- Hetero - must use larger organic molecules as the starting point for anabolism
- Auto - can use CO2 as the starting point for anabolism (may also be able to use larger organic molecules)
What are the prefixes that describe energy requirements?
Prefixes that describe chemical requirements:
- Chemo - must use oxidation-reduction reactions to obtain chemical energy
- Photo - can use light to obtain chemical energy (may also be able to use oxidation-reduction reactions)
What are the prefixes that describe carbon requirements?
Prefixes that describe carbon requirements:
- Hetero - must use larger organic molecules as the starting point for anabolism
- Auto - can use CO2 as the starting point for anabolism (may also be able to use larger organic molecules)
What are the four different combinations of energy and carbon requirements involved in trophism?
What does this chart represent?
The energy and carbon requirements involved in trophism
All organisms need what two things?
- Hint:
- Powers anabolic reactions (and other things)
- Hint:
- Starting point for anabolic reactions
Source of energy, source of carbon
Why do all organisms use a source of energy and a source of carbon for?
A source of energy powers anabolic reactions (and other things).
A source of carbon is the starting point for anabolic reactions.
The point is all living organisms need to reproduce (make more cells) and other things.
List the three metabolic pathways involved in cellular respiration.
- Glycolysis
- Preparatory stage
- Energy-conserving stage
- The Krebs cycle aka tricarboxylic acid cycle or TCA cycle
- Decarboxylation
- Citric acid cycle
- Oxidative phosphorylation
- Eectron transport
- Chemiosmosis
What is the tricarboxylic acid cycle or TCA cycle?
The TCA is another name for the Krebs Cycle or the Citric Acid Cycle.
Enzymes bind through 2 models. Name them.
- Specificity
- Lock and key model
- The active site of an enzyme is specific to its substrate
- Induced fit model
- Binding to the substrate causes the enzyme to bind it more tightly
What does the lock and key model of enzyme binding mean?
It means that the active site of an enzyme is specific to its substrate, like a lock and key.
True/False
Specificity is important in regard to how enzymes work.
True
The induced fit model refers to what microbiological molecule?
Enzymes
Binding to a substrate causes the enzyme to bind it more tightly is what model?
Induced fit model
What are the two metabolic pathways involved in fermentation?
- Glycolysis
- Secondary fermentation reactions
Glycolysis and a secondary fermentation reaction are pathways involved in what type of metabolic process?
Fermentation
Fermentation is dependent on what two pathways?
- Glycolysis
- Secondary fermentation process
What molecules are the initial electron donors and final electron acceptors in aerobic cellular respiration?
Initial: glucose
Final: H2O
O2 is reduced to what as the final electron acceptor in aerobic cellular respiration?
H2O
H2O is what the final electron acceptor in aerobic cellular respiration is reduced to. What is the final electron acceptor?
O2
What is the initial electron donor in aerobic cellular respiration?
O2
What molecules are the initial electron donors and final electron acceptors in fermentation?
- Glucose
- Organic molecule derived from glucose (is reduced to the fermentaion end produce, e.g. lactic acid or ethanol)
What do aerobic cellular respiration and fermentation have in common?
The initial electron donor is glucose.
Glucose and an organic molecule derived from glucose play what roles in fermentation?
Glucose is the initial electron donor.
An organic molecule derived from glucose is the final electron acceptor.
Breaking down carbohydrates (glucose) to produce energy (turn ADP into ATP) involves what two main processes?
- Cellular respiration
- Aerobic
- Anaerobic
- Fermentation
These two main processes do what in a metabolic pathway: Cellular respiration (aerobic and anerobic) and fermentation?
Carbohydrate catabolism (breaking down carbohydrates to produce energy).
What is the process by which carbohydrates are broken down to produce energy?
Carbohydrate catabolism
What molecule is broken down to produce energy and what molecules represent that energy?
Glucose is broken down to turn ADP into ATP.
What is the energy that is produced in carbohydrate catabolism?
ATP (ADP is turned into ATP)
Glucose is what type of macromolecule?
Carbohydrate
How much ATP is produced in aerobic cellular respiration?
Produces a large amount of ATP (up to 38 ATP per glucose)
A large amount of ATP (38) is produced through what metabolic pathway?
Aerobic cellular respiration
What molecule is catabolized in fermentation to produce 2 ATP?
Glucose
How much ATP is produced in fermentation?
A small amount (2 ATP per glucose molecule)
2 ATP per glucose are produced by what metabolic pathway?
Fermentation
What metabolic pathways produce 2 ATP and 38 ATP respectively?
Fermentation, aerobic cellular respiration
Aerobic cellular respiration and fermentation produce ATP from what molecule?
Glucose
What molecule is catabolized in aerobic cellular respiration to produce 38 ATP?
Glucose
Do aerobic cellular respiration and fermentation both use carbohydrate catabolism?
Yes
What is the generic reaction for aerobic cellular respiration?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
In this reaction, what molecule is the carbohydrate?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
C6H12O6
In this reaction, what molecule is the initial electron donor?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
C6H12O6
In this reaction, what molecule is the final electron acceptor?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
O2
In this reaction, what molecule is the final electron acceptor reduced to?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
H2O
In this reaction, what are the ADP, inorganic phosphate and ATP used/produced on each side of the equation?
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
38 ADP + Pi —-> 38 ATP
True/False
Since molecules can enter aerobic cellular respiration at various points in the cyle, the amount of energy gained from various molecules (protein, carbohydrate and lipids) is based on where they enter cycle.
True
Proteins can enter aerobic cellular respiration at which metabolic pathways?
Glycolysis, decarboxylation and the Krebs Cycle
Carbohydrates can enter aerobic cellular respiration at which metabolic pathways?
Glycolysis
Lipids can enter aerobic cellular respiration at which metabolic pathways?
Glycolycis and decarboxylation
Do all enzymes have an allosteric site?
No.
Label each reaction as reduced or oxidized:
- NAD+ + H+ to NADH
- FADH2 to FAD + 2H+
- NADP+ + H+ to NADPH
- NAD+ + H+ is reduced to NADH
- FADH2 is oxidized to FAD + 2H+
- NADP+ + H+ is reduced to NADPH
Is the tricarboxylic acid cycle another name for the Krebs Cycle and the Citric Acid Cycle?
Yes.
What’s another name for the tricarboxylic acid cycle?
The Krebs Cycle or the Citric Acid Cycle.
What’s another name for the Krebs Cycle?
The Citric Acid cycle or the tricarboxylic acid cycle.
Are the following true about this reaction? C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
- The initial electron donor is C6H12O6 (the glucose molecule)
- The final electron acceptor is O2
- The final electron acceptor is reduced to H2O
- CO2 is an ending organic molecule
All true.
In what metabolic process do the following occur?
- The initial electron donor is C6H12O6 (the glucose molecule)
- The final electron acceptor is O2
- The final electron acceptor is reduced to H2O
- CO2 is an ending organic molecule
Aerobic cellular respiration
What is the general chemical formula for the metabolic process that results in the following and what is the name of that metabolic process?
- The initial electron donor is C6H12O6 (the glucose molecule)
- The final electron acceptor is O2
- The final electron acceptor is reduced to H2O
- CO2 is an ending organic molecule
Aerobic cellular respiration
C6H12O6 + 6 O2 —–> 6 CO2 + 6 H2O
Does the statement: “The amount of energy gained from various molecules is based on where they enter cycle” pertain only to aerobic cellular respiration?
No, it also refers to fermentation.
At what stages of aerobic cellular respiration can protein enter?
Glycolysis, decarboxylation and the Krebs Cycle.
What macromolecule can enter aerobic cellular respiration at these stages: Glycolysis, decarboxylation and the Krebs Cycle.
Proteins
At what stage in aerobic cellular respiration can carbohydrates enter?
Glycolysis
What macromolecule can enter aerobic cellular respiration only at glycolysis?
Carbohydrates
Lipids can enter aerobic cellular respiration at which stages?
Glycolysis and decarboxylation.
Which macromolecule can enter aerobic cellular respiration at both glycolysis and decarboxylation but not the Krebs Cycle?
Lipids
What are the three stages of aerobic cellular respiration?
Glycolysis, the Krebs Cycle and oxidative phosphorylation
Glycolysis, the Krebs Cycle and oxidative phosphorylation are three stages of what?
Aerobic cellular respiration
What is this reaction: C6H12O6 + 6 O2 (+38 ADP + 38Pi) —-> 6CO2 + 6H2O (+38 ATP)
Aerobic cellular respiration.
What is the chemical formula for aerobic cellular respiration?
C6H12O6 + 6O2 (+38 ADP + Pi) —-> 6CO2 + 6H2O (+38 ATP)
How many carbon dioxide and water molecules are produced in aerobic cellular respiration?
Six
C6H12O6 + 6O2 (+38 ADP + 38Pi) —-> 6CO2 + 6H20 (+38 ATP)
How many glucose molecules does it take to produce 12 CO2 molecules in aerobic cellular respiration?
Two glucose molecules
C6H12O6 + 6O2 (+38 ADP + 38Pi) —-> 6CO2 + 6 H20 (+38 ATP)
Where do ADP + Pi and ATP belong in this chemical equation, how many and what is the reaction?
C6H12O6 + 6O2 —-> 6CO2 + 6 H20
C6H12O6 + 6O2 (+38 ADP + 38Pi) —-> 6CO2 + 5 H20 (+38 ATP)
Aerobic cellular respiration
What is similar between aerobic and anerobic cellular respiration?
Both aerobic and anaerobic cellular fermentation are the same in that they use the same three processes:
glycolysis, Krebs Cycle and oxidative phosphorylation (or equivalent) reactions.
Which two metabolic pathways use the same three processes: glycolysis, Krebs Cycle and oxidative phosphorylation (or equivalent (reactions).
Aerobic and anaerobic cellular respiration use the same three pathways.
Using the processes of glycolysis, the Krebs Cycle and oxidative phosphorylation (or equivalent) are characteristics of what two metabolic pathways?
Aerobic and anaerobic cellular respiration
What is the difference between the aerobic and anaerobic cellular respiration pathways?
The two main differences are the final electron acceptor and the amount of ATP produced.
Aerobic: final electron acceptor is O2, ATP = 38
Anaerobic: final electron acceptor is an inorganic molecule other than O2, ATP = 2
What two metabolic pathways are being referred to with this statement: “The two main differences are the final electron acceptor and the amount of ATP produced.”
Aerobic and anaerobic cellular respiration.
What is the final electron acceptor in aerobic cellular respiration?
O2
T/F
Aerobic cellular respiration does not use O2 as the final electron acceptor.
False.
Aerobic cellular respiration uses O2 as the final electron acceptor while anaerobic cellular respiration uses a different molecule (usually inorganic).
What is the final electron acceptor in anaerobic cellular respiration?
A different (usually inorganic) molecule than O2.
What are final electron acceptors in aerobic and anaerobic cellular respiration?
Aerobic = O2
Anaerobic = a different (usually inorganic) molecule
T/F
Anaerobic celllular respiration will always produce more energy than aerobic.
False.
Aerobic respiration, because the final electron acceptor, O2, is able to accept lower energy elecrons than the final electron acceptors used by anaerobic cellular respiration, will always produce more energy than anaerobic.
Which version of cellular respiration (aerobic or anaerobic) produces more energy and why?
Aerobic cellular respiration produces more energy (ATP) because O2 is able to accept lower energy electrons than the final electron acceptors in anaerobic cellular respiration.
What molecule represents the energy produced by aerobic and anaerobic cellular respiration?
ATP (Adenosine triphosphate)
The amount of ATP produced in anaerobic cellular respiration varies based on what two factors?
Type of organism and the pathway used.
Fill-in-the-blank
Because glycolysis and the Krebs cycle are involved, anerobic cellular respiration will always produce more _____ than fermentation?
ATP
Why will anaerobic cellular respiration always produce more ATP than fermentation?
Because anaerobic cellular respiration uses glycolysis and the Krebs Cycle while fermentation only uses glycolysis and a secondary fermentation reaction.
Explain why cellular respiration produces more ATP than fermentation.
Fermentation produces only small amounts of ATP (only two molecules for each molecule of starting material) because so much of the original energy in glucose remains in the chemical bonds of the organic end-products, such as lactic acid or ethanol. Respiration is able to fully use this energy by converting the reactants to CO2 and using the resulting electrons to power the electron transport chain to make ATP.
Fermentation produces how many molecules of ATP for each molecule of starting material?
2 ATP
Why does fermentation produce only small amounts of ATP?
Because so much of the original energy in glucose remains in the chemical bonds of the organic end-products, such as lactic acid or ethanol. Respiration is able to fully use this energy by converting the reactants to CO2 and using the resulting electrons to power the electron transport chain to make ATP.
Where does much of the original energy in glucose remain in fermentation?
In the chemical bonds of the organic end products, such as lactic acid or ethanol.
From the original energy in glucose, what remains in the chemical bonds of the organic end-products, such as lactic acid or ethanol in fermentation?
Energy
What is cellular respiration able to fully use by converting the reactants to CO2 and using the resulting electrons to power the electron transport chain (fermentation cannot do this)?
Energy
Cellular respiration is able to fully use energy by converting the reactants to ______ and using the resulting electrons to power the electron transport chain.
CO2
In respiration, the original energy in glucose is fully used by converting ______ to CO2 and using the resulting electrons to power the electron transport chain to make ATP.
… the reactants…
In respiration, the original energy in glucose is fully used by converting the reactants to CO2 and using the resulting electrons to power ____________ to make ATP.
… the electron transport chain…
In what type of metabolic pathway is the original energy in glucose fully used by converting the reactants to CO2 and using the resulting electrons to power the electron transport chain to make ATP.
Cellular respiration
Since O2 is able to accept very low energy electrons, what does that mean for aerobic cellular respiration vs. anaerobic?
Make more ATP (38) vs. anaerobic (2)
What is the main reason why cellular respiration produces more ATP than fermentation?
It uses O2 as the final electron acceptor.
Why does using O2 as the final electron acceptor help aerobic cellular respiration produce more ATP?
Because O2 can accept very low energy electrons, which means that more energy can be used to make ATP.
What does fermentation use as the final electron acceptor?
An organic molecule derived from glucose.
Why does fermentation use an organic molecule derived from glucose as the final electron acceptor?
Because these molecules will only accept higher energy eleectrons, which means that there is less energy available to make ATP.
T/F
Fermentation uses a final electron acceptor derived from glucose (not O2) that will only accept higher energy electrons.
True
Why does fermentation yield less energy than cellular respiration?
Because fermentation uses an organic molecule derived from glucose as the final electron acceptor. These molecules will only accept higher energy electrons which means that there is less energy available to make ATP.
When the final electron acceptor in a metabolic pathway will only accept higher energy electrons, how does that affect energy production?
There will be less energy available to make ATP.
List types of foods or beverages produced by bacterial fermentation.
- Microorganisms that produce lactic acid as a fermentation end product are used to make fermented milk products (yogurts and cheeses), sauerkraut and kimchi.
- Yeasts produce ethanol and CO2 through fermentation. The ethanol is used to make alcoholic beverages, while the CO2 is used to make leavened baked goods.
- Some microorganisms produce acetic acid through fermentation which is used to make vinegars.
Fermented milk products (yogurts and cheeses), sauerkraut and kimchi and made by microorganisms that produce what?
Lactic acid
What is the fermentation end product of the organisms used to make fermented milk products (yogurts and cheeses), sauerkraut and kimchi?
Lactic acid
Lactic acid is the fermentation end product of the organisms used to make what foods?
Fermented milk products (yogurts and cheeses), sauerkraut and kimchi
Yogurt, cheese, sauerkraut, kimchi, leavened baked goods and vinegars are produced using what type of metabolic pathway?
Fermentation
What do yeasts produce through fermentation and what are these products used for?
Ethanol and CO2; used to make alcoholic beverages and leavened baked goods
Alcohol and leavened baked goods are produced by microorganisms that produce what?
Ethanol and CO2
What are the microorganisms that are used to produce alcohol and leavened baked goods?
Yeasts
Some microorganisms produce _______ through fermentation that are used to make vinegars?
Acetic acid
Acetic acid through fermentation is used to make what product?
Vinegar
Test results for review:
-
Carbohydrate fermentation assays
- pH indicator: phenol red - red at neutral, yellow at acidic
- Gas indicator: inverted Durham tube
What two indicators are tested by carbohydrate fermentation assays?
Test results for review:
-
MRVP test (methyl red and Voges-Proskauer) differentiate between Escherichia coli and Enterobacter cloacae
- pH indicator: methyl red - red at acidic (E. coli at 4.5 pH)
- Acetoin presence - Enterobacter produces acetoin, red/pink with ring around surface of culture
Name the two indicators tested for in the MRVP test?
What is the name of the MRVP test and for what is it an indicator?
Methyl red and Voges-Proskauer
Differentiate between Escherichia coli and Enterobacter cloacae.
How do carbohydrate fermentation assays detect production of acid and/or gas as a result of fermentation?
Carbohydrate fermentation assays use a pH indicator and an overturned Durham tube to detect production of acid and gas as a result of fermentation. The pH indicator (phenol red) is red at neutral pH and yellow in acidic pH. The overturned Durhan tube is initally filled with media, but will collect any produced gas, which will form a bubble in the tube.
What is it that uses a pH indicator and an overturned Durham tube to detect production of acid and gas as a result of fermentation?
Carbohydrate fermentation assays
What is the carbohydrate fermentation assay that is used as a pH indicator?
Phenol red
What color is the carbohydrate fermentation assay, phenol red, in the presence of neutral pH?
It remains red
What color does the carbohydrate fermentation assay, phenol red, turn in the presence of acidic pH?
Yellow
When the carbohydrate fermentation assay, phenol red, turns yellow, what does that indicate?
Acidic pH
What is an overturned Durham tube used as a carbohydrate fermentation assay an indication of?
Gas
How is gas indicated in the carbohydrate fermentation assay called the overturned Durham tube?
The overturned Durham tube with no gas production will have medium in the tube, whereby with gas production, there will be an air bubble.
What are the four possible results to a carbohydrate fermentation assay?
- No fermentation
- Acid only
- Gas only
- Acid and gas
What are the color outcomes of phenol red as a carbohydrate fermentation assay on these four possible results?
- No fermentation - red
- Acid only - yellow
- Gas only - red
- Acid and gas - yellow
What are the outcomes of the overturned Durham tube to these carbohydrate fermentation assays?
- No fermentation - no bubble
- Acid only - no bubble
- Gas only - bubble
- Acid and gas - bubble
How does fermentation allow the MRVP test to distinguish between Escherichia coli and Enterobacter cloacae?
MR (Methyl Red) and VP (Voges-Proskauer test)
Escherichia coli and Enterobacter cloacae are two very similar types of bacteria and the MRVP test helps distinguish between the two.
- MR is a pH indicator:
- E. coli fermentation produces acids with a pH of 4.5 or lower. Methyl red turns red at this pH.
- Enterobacter do not produce many acids so the pH is higher. Methyl red stays yellow at this pH.
- VP tests for the presence of acetoin in media:
- E. coli does not form acetoin. VP will be light bron/yellow.
- Enterobacter forms acetoin. The media will turn red/pink (often in a rim around the surface of the culture).
What two microorganisms is the MRVP test used to distinguish?
Escherichia coli and Enterobacter cloacae
What tests make up the MRVP test?
Methyl Red and Voges-Proskauer tests
What does the MRVP test do?
Differentiates between Escherichia coli and Enterbactor cloacae?
How is the MRVP test able to differentiate between Escherichia coli and Enterobactor cloacae?
- E. coli* fermentation produces acids with a pH of 4.5 or lower. Methyl red turns red at this pH.
- Enterobacter* do not produce many acids so the pH is higher. Methyl red stays yellow at this pH.
- E. coli* does not form acetoin. VP will be light brown/yellow.
- Enterobacter* forms acetoin. The media will turn red/pink (often in a rim around the surface of the culture).
How can the MRVP test differentiate between Escherichia coli and Enterobacter cloacoa?
E. coli fermentation:
- produces acids, dropping pH to 4.5 to cause methyl red to turn red
- does not produce acetoin so Voges-Proskauer is light brown/yellow
Enterobacter cloacae:
- doesn’t produce acids so methyl red turns yellow
- produces acetoin so Voges-Proskauer will turn red/pink with a ring around the surface
Which bacteria tested with the MRVP test produces acetoin?
Enterobacter cloacae
Which bacteria produces acids that show on the MRVP test?
Echerichia coli
Choose the right option
Enterobacter cloacae produce (acid/acetoin) which will turn the (methyl red/Voges-Proskauer) test (yellow or red/pink with ring)?
Enterobacter cloacae produce acetoin which will turn the Voges-Proskauer test red/pink with ring?
Escherichia coli produce (acid/acetoin) which will turn the (methyl red/Voges-Proskauer) test (yellow or red)?
Escherichia coli produce acids which will turn the methyl red test red.
What are the starting molecules in each cycle of aerobic cellular respiration?
Glycolysis - glucose (6-carbon molecule - initial electron donor)
Decarboxylation and the Krebs Cycle - 2 pyruvic acids (2 carbons each from glycolysis)
Oxidative phosphorylation - none
What are the ending molecules in each cycle of aerobic cellular respiration?
Glycolysis - 2 pyruvic acids (3 carbons each)
Decarboxylation and the Krebs Cycle - 6 CO2
Oxidative phosphorylation - none
What are the starting and ending ATP or ADP + Pi numbers in each cycle of aerobic cellular respiration?
Glycolysis
- Starting: 2 ATP and 4 ADP + Pi
- Ending: 2 ADP + 2 Pi and 4 ATP (net 2 ATP)
Decarboxylation and Krebs Cycle
- Starting: 2 ADP + 2 Pi
- Ending: 2 ATP
Oxidative phosphorylation
- Starting: 34 ADP + Pi
- Ending: 34 ATP
What are the starting and ending electron carriers in all three stages of aerobic cellular respiration?
Glycolysis
- Starting: 2 NAD+ + 2 H+
- Ending: 2 NADH
Decarboxylation and the Krebs Cycle
- Starting: 8 NAD+ + 8 H+ and 2 FAD + 4 H+
- Ending: 8 NADH and 2 FADH2
Oxidative phosphorylation
- Starting: 10 NADH and 2 FADH2 (from glycolysis and decarb/Krebs)
- Ending: 10 NAD+ + 10 H+ and 2 FAD + 4 H+ (oxidized)
What are the starting O2 or H2O molecules in all three segments of aerobic cellular respiration?
Glycolysis
- Starting: none
- Ending: none
Decarboxylation and the Krebs Cycle
- Starting: none
- Ending: none
Oxidative phosphorylation
- Starting: 6 O2 + 24 H+
- Ending: 12 H2O (reduced - final electron acceptor)
What are the intial electron donor and the final electron acceptor in aerobic cellular respiration and in which of the three processes do they occur?
Glucose, C6H12O6, a 6-carbon molecule, is the initial electron donor in glycolysis.
H2O is the final electron acceptor in oxidative phosphorylation.
Where does carbon dioxide come in during aerobic cellular respiration and what role does it play?
Six carbon dioxide molecules (6 CO2) are the ending organic molecules in decarboxylation and the Krebs Cycle.
What are the electron carriers involved in aerobic cellular respiration and in what processes do they appear?
Glycolysis
- 2 NAD+ + 2H+ –> 2 NADH
Decarboxylation and the Krebs Cycle
- 8 NAD+ + 8 H+ –> 8 NADH
- 2 FAD + 4 H+ –> 2 FADH2
Oxidative phosphorylation
- 10 NADH (from 1st 2 pathways) –> 10 NAD+ + 10 H+
- 2 FADH2 (from 1st 2 pathways) –> 2 FAD + 4 H+
What is the final electron acceptor in aerobic cellular respiration and is it oxidized or reduced?
H2O, reduced
How many ADP + Pi and ATP are used and produced in aerobic cellular respiration?
Glycolysis (net 2 ATP)
- 2 ATP –> 2 ADP + 2 Pi
- 4 ADP + Pi –> 4 ATP
Decarboxylation and the Krebs Cycle
- 2 ADP + Pi –> 2 ATP
Oxidative phosphorylation
- 34 ADP + 34 Pi –> 34 ATP
What molecule is the first reactant in the Krebs Cycle?
Two 3-carbon pyruvic acids
What is the last molecule produced in glycolysis?
Two 3-carbon pyruvic acids
What are two other names for the Krebs Cycle?
Tricarboxylic acid cycle or TCA cycle
T/F
The tricarboxylic acid cycle occurs only once per glucose molecule.
False.
The tricarboxylic acid cycle (TCA) or the Krebs Cycle cycles once for each 3-carbon pyruvid acid molecules, both of which result from a single glucose molecule. In other words, the tricarboxylic acid cycle cylces twice for each glucose molecule.
What is the summary of molecules resulting from the TCA cycle and are they reduced or oxidized?
- 2 pyruvic acids (from glycolysis) oxidized to 6 CO2 which leave the reaction
- 8 NAD+ + H+ reduced to NADH
- 2 FAD + 4 H+ reduced to FADH2
- 2 ADP + Pi make 2 ATP
Are the electron carriers reduced or oxidized in each of the processes of glycolysis, TCA cycle and oxidative phosphorylation?
Glycolysis:
- 2 NAD+ + 2 H+ reduced to NADH
Tricarboxylic acid cycle
- 8 NAD+ + 8 H+ reduced to 8 NADH
- 2 FAD + 4 H+ reduced to 2 FADH2
Oxidative phosphorylation (the oxidation is needed to release H+ ions to the electron transport cycle)
- 10 NADH oxidized to 10 NAD+ + 10 H+
- 2 FADH2 oxidized to 2 FAD + 4 H+
What electron carrier that’s used in aerobic cellular respiration is not used in fermentation?
FADH2
Each glucose molecule that enters fermentation will go through what process that aerobic cellular respiration uses?
Glycolysis
Which process does aerobic cellular respiration have in common with fermentation?
Glycolysis
Glycolysis is a process of fermentation that is has in common with which other metabolic pathway?
Aerobic cellular respiration
Each glucose molecule that enters fermentation will go through glycolysis and what else?
One secondary fermentation reaction like lactic acid, ethanol or another.
Glycolysis produces what molecules that enter into secondary fermentation reactions?
Two 3-carbon pyruvic acids molecules
What do the two 3-carbon pyruvic acids from glycolsis reduce to in lactic acid fermentation?
Two 3-carbon lactic acid molecules
What do the two 3-carbon pyruvic acid molecules reduce to in ethanol fermentation?
Two 2-carbon ethanols + 2 CO2
What are the final electron acceptors in lactic acid fermentation and ethanol fermentation?
Two 3-carbon lactic acids in lactic acid fermentation
Two 2-carbon ethanols + 2 CO2 in ethanol fermentation
What are the starting and ending electron carriers in fermentation?
2 NADH (from glycolysis) oxidized to 2 NAD+ + 2 H+ for both lactic acid and ethanol fermentation.
What are the numbers of starting and ending ATP/ADP + Pi in fermentation and from what process do they come?
2 ATP –> 2 ADP + 2 Pi
4 ADP + 4 Pi –> 4 ATP
(net 2 ATP)
Produced in glycolysis
What are the starting and ending ATP/ADP + Pi molecules in the secondary fermentation reactions of fermentation?
Zero
What are the starting and ending O2 and H2O molecules in fermentation?
Zero
What are the electron carriers in the two stages of fermentation?
Glycolysis:
- 2 NAD+ + 2 H+ –> 2 NADH
Secondary fermentation reaction (lactic acid or ethanol)
- 2 NADH (from glycolysis) oxidized to 2 NAD+ + 2 H+
What is the ending electron carrier in glycolysis and is it reduced or oxidized?
2 NADH, reduced
How many ATPs result from fermentation and in what process are they produced?
2 ATPs, glycolysis
What is the summary of the chemical reaction of photosynthesis found in plants, algae and cyanobacteria? In other words, the photosynthentic process that uses H2O as an electron donor.
6CO2 + 6 H2O + (light energy) —> C6H12O6 + 6O2
In photosynthesis found in plants, algae and cyanobacteria, what is the electron donor?
H2O
The photosynthesis that uses H2O as the electron donor is used in what three types of organisms?
Plants, algae and cyanobacteria
Plants, algae and cyanobacteria use what type of metabolic process and what is the electron donor in that process?
Photosynthesis, H2O
Is photosynthesis and anabolic or catabolic process?
Anabolic
What is the electron donor in photosynthesis and is it oxidized or reduced?
H2O, oxidized (releases O2)
What are the 2 steps in photosynthesis?
Light-dependent and light-independent (Calvin cycle).
Light-dependent and light-independent (Calvin cycle) are the names of what?
The 2 steps in photosynthesis.
What is another name for the Calvin cycle?
Light-independent step in photosynthesis
What do the light-dependent reactions in photosynthesis produce and what is dependent on these products?
Produces ATP, NADPH and O2 from ADP + Pi, NADP+ + H+ and H2O.
The light-independent step (Calvin cycle) is dependent on the products from the light-dependent reactions.
Produces ATP, NADPH and O2 from ADP + Pi, NADP+ + H+ and H2O.
Light-dependent reaction of photosynthesis
The light-independent step (Calvin cycle) is dependent on the products from what other step?
From the light-dependent step that produces ATP, NADPH and O2 from ADP + Pi, NADP+ + H+ and H2O
What does the light-independent reaction in photosynthesis produce?
Three 3-carbon molecules (Glycerol 3-phosphate or G3P) that can be used to make glucose (and other molecules)
Glycerol-3-phosphate is produced by what metabolic process and what is it used for?
The light-independent reaction (the 2nd step) in photosynthesis
Used to make glucose and other molecules
In the light-independent reaction in photosynthesis, what is created per 1 glucose (2 G3Ps)?
18 ATP to 18 ADP + Pi and
12 NADPH into 12 NADP+ + 12 H+
What is required to convert
- 18 ATP to 18 ADP + Pi and
- 12 NADPH into 12 NADP+ + 12 H+
and in what metabolic process does this occur?
1 glucose (2 G3P)
Light-independent reaction in photosynthesis
What are the products of the two reactions in photosynthesis?
Light-dependent: ATP, NADPH, O2
Light-independent (Calvin cycle): 18 ADP + Pi, 12 NADP+ + H+ per glucose
What part of photosynthesis has these products and what are they produced from?
ATP
NADPH
O2
Light-dependent
ADP + Pi
NADP+ + H+
H2O
What are the products of light-independent (Calvin cycle) part of photosynthesis and what are they produced from?
Three 3-carbon molecules (Glycerol-3-phosphate (G3P) that are used to make glucose and other molecules.
The light-independent reaction also convert per glucose:
18 ATP to 18 ADP + Pi
12 NADPH to 12 NADP+ + H+
In what part of photosynthesis is this converted?
18 ATP to 18 ADP + Pi
Light-independent reaction
In what part of photosynthesis is this converted?
ADP + Pi to ATP
Light-dependent
In what part of photosynthesis is this converted?
12 NADPH to 12 NADP+ + H+
Light-independent
In what part of photosynthesis is this conversion taking place?
18 ATP to 18 ADP + Pi
Light-independent
How are the light-dependendent and light-independent reactions in photosynthesis linked?
The ATP and NADPH from the light-dependent reactions are needed to provide chemical energy and high energy electrons to the light-independent reactions.
What 2 molecules from the light-dependent reactions are needed to provide chemical energy and high energy electrons to the light-independent reactions.
ATP and NADPH
ATP and NADPH from the light-dependent reactions provide the light-independent reactions with high energy electrons that are used how?
Reducing power.
Reducing power is provided to the light-independent reactions through what molecules?
High energy electrons
How is the ATP generated in catabolism used in anabolism?
The ATP generated in catabolism (light-dependent) provides chemical energy to construct more complicated molecules in anabolism. The molecules made in anabolism (light-independent) are eventually used to allow the cell to divide (reproduce).
What is an amphibolic pathway?
Amphibolic pathways are dual-purpose pathways that function in both anabolism and catabolism. Intermediates shared between reactions can be used for either reaction.
What is this describing?
Dual-purpose pathways that function in both anabolism and catabolism.
Amphibolic pathways
What is this describing?
Pathways with intermediates that are shared between reactions and can be used for either reaction.
Amphibolic pathways
What is an example of an amphibolic pathway?
The Krebs cycle (Citric acid cycle)
What are the roles that aerobic respiration, anaerobic respiration and fermentation play in the carbon cycle?
In the carbon cycle…
Larger carbon molecules are broken down into:
- Aerobic respiration - to CO2 (complete breakdown)
- Anerobic respiration - to CO2 (complete breakdown)
- Fermentation - some fermentation reactions produce ethonol (2 carbons) and one CO2 (partial breakdown)
CO2 is fixed and converted into larger carbon molecules in:
- Photosynthesis
What is the role of aerobic respiration, anaerobic respiration, fermentation and photosynthesis in the oxygen cycle?
In the oxygen cycle…
O2 is converted to H2O in:
- Aerobic respiration - O2 is converted to H2O. Where O2 acts as the final electron acceptor and is reduced to H2O.
H2O is converted into O2 in:
- Photosynthesis - (oxygenic only) H2O is used as the initial electron donor and is oxidized to O2.
What is the role of aerobic respiration, anaerobic respiration, fermentation and photosynthesis in the nitrogen cycle?
In the nitrogen cycle…
Nitrogen containing molecules are broken down on their way to:
- Aerobic respiration
- Anaerobic respiration
- Fermentation
Ammonia (NH4) and other nitrogen-containing compounds (NO3, NO2, NO, N2O) are reduced to gaseous nitrogen (N2) in:
- Anaerobic respiration where the nitrogen-containing compounds are used as a final electron acceptor and are reduced to N2.
Nitrogen fixation (conversion of N2 to NH4) is an anabolic reaction (requires a large amount of ATP) that is perfomed by soil bacteria and bacteria that are symbiotic with legumes, such as species of Rhizobium.
In the nitrogen cycle, nitrogen containing molecules are broken down on their way to which three types of metabolism?
Aerobic, anaerobic and fermentation
Ammonia (NH4) and other nitrogen-containing compounds (NO3, NO2, NO, N2O) are reduced to gaseous nitrogen (N2) in what metabolic processes?
Anaerobic respiration. This is where nitrogen-containing compounds are used as a final electron acceptor and are reduced to N2.
Nitrogen fixation (conversion of N2 to NH4 (ammonia)) is an anabolic reaction (requires a large amount of ATP) that is performed by what?
Soil bacteria and bacteria that are symbiotic with legumes, such as species of Rhizobium.
In the carbon cycle, larger carbon molecules are broken down in what metabolic processes?
- Aerobic respiration - to CO2 (complete breakdown)
- Anerobic respiration - to CO2 (complete breakdown)
- Fermentation - some fermentation reactions produce ethonol (2 carbons) and one CO2 (partial breakdown)
In what metabolic processes is CO2 fixed and converted into larger carbon molecules?
Photosynthesis only
In the oxygen cycle, O2 is converted to H2O in what metabolic processes?
Aerobic respiration.
O2 is the final electron acceptor and is reduced to H2O.
In the oxygen cycle, H2O is converted to O2 in which metabolic process?
Photosynthesis (oxygenic only).
H2O is used as the initial electron donor and is oxidized to O2.
Which metabolic pathways are involved in the carbon cycle?
- Larger carbon molecules are broken down in aerobic and anaerobic cellular respiration and some fermentation.
- CO2 is fixed and converted into large carbon molecules in Photosynthesis.
Aerobic cellular respiration, anaerobic cellular respiration, fermentation and photosynthesis are all involved in what biogeochemical cycle?
Carbon cycle
Aerobic cellular respiration and photosynthesis are the only two metabolic processes required to complete out what biogeochemical cycle?
Oxygen cycle
In what biogeochemical cycle are aerobic respiration, anaerobic respiration, fermentation and soil bacteria required to complete the cycle?
Nitrogen cycle
What three metabolic processes are involved in breaking down molecules in the carbon cycle and the nitrogen cycle?
Aerobic respiration, anaerobic respiration and fermentation.
What are larger carbon molecules broken down to in the carbon cycle?
CO2
What are the two molecules involved in the oxygen cycle?
O2 and H2O
In the oxygen cycle, O2 is converted to H2O in what metabolic pathway and is O2 oxidized or reduced to H2O?
Aerobic cellular respiration
Reduced
In the oxygen cycle, H2O is used as the initial electron donor by what metabolic pathway?
Is H2O oxidized or reduced to O2?
Photosynthesis
Oxidized
What is required by the light-dependent reaction?
In what metabolic pathway is this present?
Light energy is required
Photosynthesis
What are the starting and ending organic molecules in light-dependent reactions?
There are none
What are the starting ATP/ADP + Pi needed in light-dependent reactions?
Starting ADP + Pi
Ending ATP
What are the starting and ending electron carriers in light-dependent reactions?
Starting NADP+ + H+
Ending NADPH (reduced)
What are the starting and ending molecules in light-dependent reactions?
Starting: H2O (electron donor)
Ending: O2 (oxidized)
What are the starting and ending molecules in light-independent reactions?
Starting: 6 CO2
Ending: 1 glucose (C6H12O6) (Reduced)
What are the starting and ending ATP/ADP + Pi in light-independent reactions?
Starting: 18 ATP (from light-dependent)
Ending: 18 ADP + Pi
What are the starting and ending electron carriers in light-independent reactions?
Starting: 12 NADPH (from light-dependent reaction)
Ending: 12 NADP+ + H+ (oxidized)
What are the starting and ending O2 or H2O molecules in light-independent reactions?
There are none.
How are ATP and ADP + Pi used in light-dependent and light-independent reactions?
Light-dependent:
- Starting ADP + Pi
- Ending ATP
Light-independent:
- Starting 18 ATP
- Ending 18 ADP + Pi
How are electron carriers moved between light-dependent and light-independent reactions?
Light-dependent:
- Starting NADP+ + H+
- Ending NADPH (reduced)
Light-independent
- Starting NADPH (from light-dependent reaction)
- Ending NADP+ + H+ (oxidized)
List the classifications of bacteria based on temperature.
- Psychrophiles: cold-loving (between -5°C and 30°C)
- Psychotroph: organisms that grow slowly at 0°C but still grow well at room temp (often cause spoilage)
- Mesophiles: moderate-temperature loving (20°C - 45° C)
- Thermophiles: heat-loving (> 45°C)
- Hyperthermophiles (usually > 80°C)
List classification of bacteria based on pH.
- Acidophiles - grow in more acidic environments
- Neutrophiles - grow in neutral environments
- Alkaliphiles - grow in basic environments
List classifications of bacteria based on osmotic pressure.
- Extreme halophiles - well-adapated to high salt concentrations
- Obligate halophiles - require high salt concentrations to grow
- Facultative halophiles - do not require high salt concentrations but are able to grow in concentrations of 2%
Which defines the term below:
Psychrophiles
- Cold loving (-5°C to 30°C)
- Moderate-loving (20°C to 45°C)
- Grow slowly at 0°C and grow well at room temp
- Heat-loving (> 45°C)
- Live at very high temps (> 80°C)
Psychrophiles = 1. Cold-loving (-5°C to 30°C)
Which defines the term below:
Mesophiles
- Cold loving (-5°C to 30°C)
- Moderate-loving (20°C to 45°C)
- Grow slowly at 0°C and grow well at room temp
- Heat-loving (> 45°C)
- Live at very high temps (> 80°C)
Mesophiles = 2. Moderate loving (20°C to 45°C)
Which defines the term below:
Thermophiles
- Cold loving (-5°C to 30°C)
- Moderate-loving (20°C to 45°C)
- Grow slowly at 0°C and grow well at room temp
- Heat-loving (> 45°C)
- Live at very high temps (> 80°C)
Thermophiles = 4. Heat-loving (> 45°C)
Which defines the term below:
Psychotroph
- Cold loving (-5°C to 30°C)
- Moderate-loving (20°C to 45°C)
- Grow slowly at 0°C and grow well at room temp
- Heat-loving (> 45°C)
- Live at very high temps (> 80°C)
Psychotroph = 3. Grow slowly at 0°C and grow well at room temp
Which defines the term below:
Hyperthermophiles
- Cold loving (-5°C to 30°C)
- Moderate-loving (20°C to 45°C)
- Grow slowly at 0°C and grow well at room temp
- Heat-loving (> 45°C)
- Live at very high temps (> 80°C)
Hyperthermophiles = 5. Live at very high temps (> 80°C)
Which organism grows above 80°C?
Hyperthermophile
Which organism grows slowly at 0°C but will grow well at room temperature and is responsible for spoilage?
Pyschotrophs
Which organisms grows above 45°C and are heat-loving?
Thermophiles
Which organisms love moderate temps (20°C to 45°C)?
Mesophiles
Which organisms are cold-loving (-5°C to 30°C)?
Psychrophiles
Match the organism with the definition.
Acidophiles
- Grow in acidic environments
- Grow in neutral pH environments
- Grow in basic environments
Acidophiles = 1. Grow in acidic environments
Match the organism with the definition.
Neutrophiles
- Grow in acidic environments
- Grow in neutral pH environments
- Grow in basic environments
Neutrophiles = 2. Grow in neutral pH environments
Match the organism with the definition.
Alkaliphile
- Grow in acidic environments
- Grow in neutral pH environments
- Grow in basic environments
Alkaliphile: 3. Grow in basic environments
Which organisms grow in a basic pH environment?
Alkaliphiles
Which organisms grow in an acidic pH?
Acidophiles
Which organisms grow best in neutral pH environments?
Neutrophiles
Match the organism to the definition:
Extreme halophile
- Well-adapted to high salt concentrations
- Require high salt concentrations to grow
- Do not require high salt concentrations but are able to grow at 2% concentrations
Extreme halophile = 1. Well-adapted to high salt concentrations
Match the organism to the definition:
Obligate halophile
- Well-adapted to high salt concentrations
- Require high salt concentrations to grow
- Do not require high salt concentrations but are able to grow at 2% concentrations
Obligate halophile = 2. Require high salt concentrations to grow
Match the organism to the definition:
Facultative halophile
- Well-adapted to high salt concentrations
- Require high salt concentrations to grow
- Do not require high salt concentrations but are able to grow at 2% concentrations
Facultative halophile = 3. Do not require high salt concentrations but are able to grow at 2% concentrations
Psychrophiles, mesophiles, thermophiles, psychotrophs and hyperthermophiles are terms classifying microbes based on what?
Temperature
Acidophiles, neutrophiles and alkaliphiles are organisms classified by what?
pH tolerance
Extreme halophiles, obligate halophiles and facultative halophiles are classifications of organisms based on what characteristic?
The salt concentration preferred to grow
This element is the structural backbone of most living matter and is used to make all of the macromolecules in the cell.
Carbon
Half of the dry weight of a cell is composed of what element?
Carbon
Carbon composes what percent of dry weight of a cell?
50%
What element is required to make all macromolecules in a cell?
Carbon
Carbon is the _________ ________ of most living matter.
Structural backbone
What element is added to media as organic molecules, often in the form of carbohydrates or protein?
Carbon
Most bacteria get what element by decomposing amino acids?
Nitrogen
Some bacteria are able to use ammonia as a source of what element?
Nitrogen
Some bacteria are able to use gaseous nitrogen from the atmosphere in a process called what?
Nitrogen fixation
Bacteria are able to get a source of nitrogen from what three sources?
- Decomposing amino acids
- Using ammonia
- Nitrogen fixation (from gaseous nitrogen in the air)
What element is necessary to have in growth media for the synthesis of amino acids and nucleotides?
Nitrogen
Amino acids are important in a growth medium for the synthesis of what?
Proteins
Nitrogen in growth medium is important to make nucleotides to make what?
Nucleic acids
Synthesis of proteins and nucleic acids can be facilitated by adding what to growth media and what are the sources of it?
Nitrogen
Decomposing amino acids, ammonia or nitrogen fixation
Why is sulfur necessary in growth media?
Is always added to synthesize sulfur-containing amino acids (methionine, cystine)
What element is provided in growth media by adding sulfate ions, hydrogen sulfide or sulfur-containing amino acids?
Sulfur
Sulfur-containing amino acids can only be synthesized if what is added to the growth media?
Sulfur
Phosphorus is often obtained as phosphate ions and is used to make nucleotides and lipids in what?
Growth media
Growth media requires what to make nucleotides and lipids?
Phosphorus
List the four elements required in growth media.
- Carbon
- Nitrogen
- Sulfur
- Phosphorus
List the four elements required in growth media and what macromolecule requires that element.
- Carbon - all macromolecules
- Nitrogen - amino acids and nucleotides
- Sulfur - Sulfur-containing amino acids
- Phosphorus - nucleotides and lipids
Of the elements required in growth media, which one is required by all macromolecules?
Carbon
Of the four elements required in a growth medium, which one is required for sulfur-containing amino acids?
Sulfur
Of the four elements required for growth media, which ones are required for nucleotides?
Nitrogen and phosphorus
Of the four elements required for growth media, which one is necessary for amino acids and nucleotides?
Nitrogen
Of the four elements required for growth media, which one is necessary for the synthesis of nucleotides and lipids?
Phosphorus
What is FTM and why is it useful as a growth medium?
Fluid thioglycolate medium is useful because thioglycolate is a reducing agent which means it reduces O2 to H2O (oxidizing the thioglycolate) to create an O2 free medium. However, it can only reduce the molecule once. Then O2 in the medium will be higher in the areas exposed to O2 like the top of a tube. This supports growth of organisms that have the enzymes to protect it from high O2 environments for purposes of differentiation.
O2 concentrations in a tube of FTM will be lowest where?
At the bottom
O2 concentration in a tube of FTM will be highest where?
At the top
What happens to O2 concentration as you move from the top to the bottom in a FTM-filled tube?
O2 concentrations decrease from top to bottom.
In an FTM tube, fast microorganism growth requires what metabolic pathway?
Aerobic cellular respiration
In an FTM tube, slow growth will occur when cells ar using what two types of metabolism?
Anaerobic cellular respiration or fermentation to make ATP
Obligate aerobes are capable of aerobic cellular respiration
(Yes/No)
Yes
Obligate anaerobes are capable of aerobic cellular respiration
(Yes/No)
No
Aerotolerant anaerobes are capable of aerobic cellular respiration
(Yes/No)
No
Facultative anaerobes are capable of aerobic cellular respiration
(Yes/No)
Yes
Microaerophiles are capable of aerobic cellular respiration
(Yes/No)
Yes
Obligate aerobes are capable of anaerobic cellular respiration and/or fermentation.
(Yes/No)
No
Obligate anaerobes are capable of anaerobic cellular respiration and/or fermentation.
(Yes/No)
Yes
Aerotolerant anaerobes are capable of anaerobic cellular respiration and/or fermentation.
(Yes/No)
Yes
Facultative anaerobes are capable of anaerobic cellular respiration and/or fermentation.
(Yes/No)
Yes
Microaerophile are capable of anaerobic cellular respiration and/or fermentation.
(Yes/No)
No
Obligate aerobes make enzymes that detoxfy oxygen.
(Yes/No)
Yes
Obligate anaerobes make enzymes that detoxfy oxygen.
(Yes/No)
No
Aerotolerant anaerobes make enzymes that detoxfy oxygen.
(Yes/No)
Yes
Facultative anaerobes make enzymes that detoxfy oxygen.
(Yes/No)
Yes
Microaerophiles make enzymes that detoxify oxygen.
(Yes/No)
No
Obligate aerobes growth at the top of an FTM tube
(Fast/Slow/No)
Fast
Obligate anaerobes growth at the top of an FTM tube
(Fast/Slow/No)
No
Aerotolerant anaerobes growth at the top of an FTM tube
(Fast/Slow/No)
Slow
Facultative anaerobes growth at the top of an FTM tube
(Fast/Slow/No)
Fast
Microaerophiles growth at the top of an FTM tube
(Fast/Slow/No)
No
Obligate aerobe growth at the middle of the tube
(Fast/Slow/No)
No
Obligate anaerobe growth at the middle of the tube
(Fast/Slow/No)
No/Slow
Aerotolerant anaerobe growth at the middle of the tube
(Fast/Slow/No)
Slow
Facultative anaerobe growth at the middle of the tube
(Fast/Slow/No)
Slow
Microaerophile growth at the middle of the tube
(Fast/Slow/No)
Fast
Obligate aerobe growth at the bottom of the FTM tube
(Fast/Slow/No)
No
Obligate anaerobe growth at the bottom of the FTM tube
(Fast/Slow/No)
Slow
Aerotolerant anaerobe growth at the bottom of the FTM tube
(Fast/Slow/No)
Slow
Facultative anaerobe growth at the bottom of the FTM tube
(Fast/Slow/No)
Slow
Microaerophile growth at the bottom of the FTM tube
(Fast/Slow/No)
No
What does the growth pattern in a tube look like for an obligate aerobe?
What does the growth pattern in a tube look like for an obligate anaerobe?
What does the growth pattern in a tube look like for an aerotolerant anaerobe?
What does the growth pattern in a tube look like for a facultative anaerobe?
What does the growth pattern in a tube look like for a microaerophile?
What two contributions came from members of Robert Koch’s laboratory to the culture of microorganisms?
- Fannie Hesse, tech for her husband in the lab, suggested agar (used in jam) for an effective setting agent.
- Robert Petri invented the streak plate method for isolating pure colonies and the plate that bears his name.
Who is Fannie Hesse?
A tech in Robert Koch’s lab who suggested the use of agar as an effective setting agent.
What did Fannie Hesse suggest as an effective setting agent in Robert Koch’s lab?
Agar
What did Robert Petri invent?
The streak plate method and the dish that bears his name.
What is the streak plate method used for?
Isolating pure cultures
What is chemically defined media?
Used when the exact chemical composition is known and is useful for experimental testing of requirements for growth and for growing fastidious (picky) organisms.
What type of media is used when the exact chemical composition is known.
Chemically defined media
What type of media is useful for experimental testing of requirements for growth and for growing fastidious (picky) organisms.
Chemically defined media
What is complex (undefined) media?
- Media where the exact chemical composition is unknown
- Complex medias are usually made from nutrients including extracts from yeasts, meat, plants or digests of proteins from other sources
- Complex medias are useful for growing bacteria inexpensively
Which type of media is the one where the exact chemical composition is unknown?
Complex (undefined) media
Which type of media is usually made from nutrients including extracts from yeasts, meat, plants or digests of proteins from other sources?
Complex (undefined) media
Which type of media is useful for growing bacteria inexpensively?
Complex (undefined) media
Which type of media is used for growing bacteria inexpensively and which one is good for growing fastidious organisms?
Complex (undefined) media - inexpensively
Chemically defined media - fastidious organisms
What is the main difference between selective, differential and enrichment media?
- Selective media - allows growth of some microorganisms while preventing the growth of others based on some property. (McConkey agar selects between Gram-negative (grow) and Gram-positive cells (don’t grow).)
- Differential media - some microorganisms appear differently due to some difference in their biology. (In MacConkey agar, acid-fermenting bacteria turn purple-pink while non-acid-fermenting bacteria turn yellowish-white.)
- Enrichment media - provides nutrients that favor the growth of particular bacteria over others, designed to increase very small numbers of the desired type of organism to detectable levels. (Blood agar contains blood components and acts as an enrichment media for a number of potentially pathogenic bacteria.)
Which type of media provides nutrients that favor the growth of particular bacteria over others?
Enrichment media
What type of media makes some organisms appear differently due to some difference in their biology?
Differential media?
What type of media allow the growth of some organisms while preventing the growth of others based on a property like Gram-negative or positive bacteria?
Selective media
What type of media is MacConkey agar when it encourages growth of Gram-negative while preventing the growth of Gram-positive bacteria?
Selective media
What type of media is MacConkey agar when acid-fermenting bacteria turn purple-pink and non-acid fermenting bacteria turn yellow-white?
Differential media
What type of media is blood agar when it acts as an enrichment media for a number of potentially pathogenic species?
Enrichment media
Match the definition with the type of media (selective, differential or enrichment):
- Allows growth of some microorganisms while preventing growth of others
- Some microorganisma appear differently due to some difference in their biology
- Provides nutrients that favoe the growth of particular bacteria over others
- Allows growth of some microorganisms while preventing growth of others - SELECTIVE
- Some microorganisma appear differently due to some difference in their biology - DIFFERENTIAL
- Provides nutrients that favoe the growth of particular bacteria over others - ENRICHMENT
Which type of media allows growth of gram-negative bacteria over gram-positive?
Selective media
What type of media makes acid-fermenting bacteria appear differently than non-acid-fermenting bacteria?
Differential media
What type of media is blood agar?
Enrichment media
What type of media is MacConkey agar?
Selective media - gram-negative grows, gram-positive does not
Differential media - acid-fermenting bacteria are purple-pink, non are yellow-white
Describe how bacteria are grown in anaerobic conditions in liquid culture (FTM).
- Reducing media is used to grow bacterial cultures under anaerobic conditions in liquid cultures.
- Reducing media contain ingredients that chemically combine with dissolved oxygen and deplete oxygen in the culture medium by reducing O2 to H2O.
- Reducing media is stored in tightly capped test tubes to prevent the reducing agent in the media from being completely oxidized.
- FTM is a reducing agent.
Reducing agents contain ingredients that do what?
Reduce O2 to H2O
What are reducing agents like FTM used for?
Growing microorganisms in anaerobic conditions.
What is FTM and does it do?
Fluid thioglycolate medium
Reduces O2 to H2O
Describe how bacteria are grown in anaerobic conditions on Petri dishes.
- To grow microorganisms on petri dishes, chambers with an anaerobic atmosphere must be used.
- Small, temporary chambers can be used with packets that contain carbon dioxide and hydrogen. The hydrogen interacts with the free O2 to make water in a reaction that requires a platinum catalyst.
- More frequent need for cultures in anaerobic conditions require glove boxes.
- Glove boxes are more permanent chambers filled with inert, oxygen-free gas.
- Rubber gloves allow the manipulation of objects inside the box and an airlock allows things to be passed into and out of the box without allowing in O2.
What two devices can be used to grow bacteria in anaerobic environment in petri dishes?
- Temporary chambers can be used with packets containing CO2 and hydrogen where the hydrogen interacts with the O2 to make water in the presence of a platinum catalyst.
- Glove boxes are more permanent and have gloves that allow maniupulation and an airlock to pass items in and out of the box
Describe the plate method for isolating single colonies.
- Sterilize loop
- Dip inoculating loop in culture
- Loop is streaked across one section of a plate
- Sterilize loop
- Loop is dragged through a small section of the first streak, which is then streaked over a second are of the plate
- Sterilize loop
- Loop is dragged through a small section of the second streak, which is then streaked over a third are of the plate.
The goal is to dilute the cells enough that single colonies are able to grow.
When is the loop dipped in the culture when preparing a streak plate?
Only at the very beginning.
Why are single colonies (like those from streak plates) important in microbiology?
Single (isolated) colonies are colonies that are founded by a single cell. In order to obtain a single colony, a single cell must be isolated on a plate so that it is far enough away from other cells that it can grow into a colony without touching growth from other cells.
What is the goal of the streak plate method?
To obtain single colonies
Describe the steps in binary fission.
- Cell elongates and DNA is replicated
- Cell wall and plasma membrane begin to constrict
- Cross-wall forms, completely separating the two DNA copies
- The cells separate
What process do these steps represent?
- Cell elongates
- Cell wall and plasma membrane begin to constrict
- Cross-wall forms, completely separating the two DNA copies
- The cells separate
Binary fission
Put these steps in the right order. What do they represent?
- Cell wall and plasma membrane begin to constrict
- Cell elongates and DNA is replicated
- The cells separate
- Cross-wall forms, completely separating the two DNA copies
- Cell elongates and DNa is replicated
- Cell wall and plasma membrane begin to constrict
- Cross-wall forms, completely separating the two DNA copies
- The cells separate
This is binary fission
Draw a typical bacterial growth curve and label the four phases of growth.
A. Lag phase
B. Log phase
C. Stationary phase
D. Death phase
In the bacterial growth phase, what is A?
Lag phase: Cells are not dividing but are metabolically active, preparing to divide (synthesizing cell components, replicating DNA, etc.)
In the bacterial growth curve, what is represented by B?
Log phase: Cells are rapiding dividing and most metabolically active.
As this phase continues, nutrient availability in the media decreases while the concentrations of toxic molecules increases. Result is slowing of cell division and increase in cell death.
What part of the bacterial growth curve is represented by C?
Stationary phase: Cell division slows and cell death increases to where they are roughly equal, so there is no net change in population of the culture.
What does D represent in the bacterial growth curve?
Death phase: The rate of cell death exceeds the new cells being produced through cell division, so the population of the culture decreases.
Put the phases (below) from the bacterial growth curve in order.
Stationary phase
Log phase
Death phase
Lag phase
A. Lag phase
B. Log phase
C. Stationary phase
D. Death phase
In what phase of the bacterial growth curve does death of cells exceed growth?
Death phase (D)
In what phase of the bacterial growth curve are cells metabolically active but not yet dividing?
Lag phase (A)
In what phase of the bacterial growth chart does cell division slow and cell death increasesto where they are roughly equal?
Stationary phase (C)
In what phase of bacterial growth curve are cells rapidly dividing and are most metabolically active?
Log phase (B)
As what phase of the bacterial growth curve continues, are nutrients decreasing while toxic molecule concentrations increase, the result being a slowing of growth?
Log phase (B)
Briefly describe plate counts and advantages and disadvantages to measuring bacterial growth.
Plate count: The idea behind a plate count is to spread a volume of liquid on a plate, allowing individual cells on the plate (which cannot be seen with th enaked eye) to grow into colonies (which can be seen with the naked eye) and count the colonies.
The results from a plate count are CFUs (colony forming units) since some bacteria form chains which are difficult to separate. Because of the difficulty of CFUs growing together, serial dilutions are necessary to get a countable result.
Advantages: inexpensive materials and only counting living cells (the only ones to grow in a culture).
Disadvantages: takes time (usually ~ 24 hours) to get readable results.
Describe the principle of turbidity used to measure bacterial growth.
Based on the principle that cells scatter light passing through the culture and that the higher the concentration, the less light is able to pass through the culture. A spectrophotometer is used to measure absorbance (optical density (OD)) of a culture.
Advantages: Get results rapidly.
Disadvantages: Requires expensive equipment (spectrophotometer). Also, to get actual concentration, must first make a standard curve by measuring OD as well as measuring the concentration using another technique (plate count or microsopic count).
Describe the method of direct microscopic count in measuring bacterial growth.
Direct microscopic count: 0.01 mL of culture is spread on a Petroff-Hausser cell counter (a slide that has a counting grid). Counting the number of cells results in a measurement of concentration (cells per volume).
Advantages: get results relatively quickly
Disadvantages: expensive equipment (counter & microscope) and get non-living cells in the count
What are the advantages and disadvantages of the plate count method for measuring bacterial growth?
Plate count
Advantages: inexpensive, get live cell count (cells that will grown into colonies)
Disadvantages: Time-consuming (wait 24 hours)
What are the advantages and disadvantages of the direct microscopic count method for measuring bacterial growth?
Direct microscope count
Advantages: get results rapidly
Disadvantages: expensive equipment, can’t differentiate non-living cells
What are the advantages and disadvantages of the turbidity method for measuring bacterial growth?
Turbidity
Advantages: Get results quickly
Disadvantages: expensive equipment and also need another measurement of the concentration like plate count or direct microscopic count. Lastly, measurement of different cell types are not comparable, as differences in cell size between species may cause cells to scatter more or less light. Only measures absorbance.
How do you do a plate count to measure bacterial growth?
Spread a volume of liquid on a plate, allow individual cells on the plate to grow into colonies and count the colonies (result is in CFUs). Serial dilutions might be necessary to get a countable result.
With what bacterial growth count method is serial dilution often used to get a countable result?
Plate count
How do you perform a direct microscopic count of bacterial growth?
Put 0.01 mL of a culture is spread on a Petroff-Hausser cell counter. Each grid represents a known volume. Counting the cells in that box results in a measurement of concentration (cells per volume).
What is the cell counter called that is used to perform a direct microscopic count of bacterial growth?
Petroff-Hausser
How do you perform the turbidity method of bacterial growth?
Put culture in a tube and pass through a spectrophotometer to measure the optical density.
What does the turbidity of a culture measure?
Optical density
What instrument is used to measure turbidity of a culture?
Spectrophotometer
