Lecture 5 - Microbial Metabolism Flashcards
Metabolism
the sum total of all energy being used and released in the body
(anabolism + catabolism = metabolism)
Catabolism
the process of breaking down larger molecules into smaller molecules
Anabolism
the process of synthesizing (building up) larger molecules
Hydrolysis
water is added as a reactant to break chemical bonds
Dehydration Synthesis
water is relased as a byproduct as bonds are formed
rnx
reaction
Are catabolic rxns endergonic or exergonic?
exergonic
(releases E)
Are anabolic reactions endergonic or exergonic?
endergonic
(uses E)
E
energy
Energy Coupling
Endergonic rxns can be used to store E within the bonds.
When those bonds are broken during a catabolic rxn, the E is released (exergonic) and can be used in other endergonic synthesis rxns.
ATP
adenosine triphosphate
ATP synthesis
ADP + P + energy –> ATP
(making ATP stores E)
ATP degradation
ATP –> ADP + P + energy
(breaking down ATP releases E)
ADP
adenosine diphosphate
catalysts
increse the rate of rxns
Most enzymes are _____.
Proteins
How do catalysts increase the rate of rxns?
Catalysts work by lowering the activation E required to initiate a rxn.
Catalysts bind to the reatants for a rxn which brings the reactants in close enough proximity with the proper orientation to react efficiently.
Enzymes are _______.
catalysts
-ase
enzyme
Explain How the Enzyme Lactase Works
Lactase binds to Lactose to break it into glucose and galactose monomers.
Sucrase breaks apart _____.
Sucrose
-ose
sugar
Substrate
the molecule that an enzyme binds to and acts on
(substrates are the reactants in the rxn)
decarboxylase
removes carbon dioxide from the substrate
cofactor AKA
coenzyme
Cofactors are typically _____ molecules.
inorganic
i.e. metal ion (iron, zinc, magnesium)
Coenzymes are typically _______ molecules.
organic
What is the function of a cofactor/coenzyme?
Cofactors and Coenzymes bind to the enzymes to make the enzyme complete and functional.
Fe
Iron
Mg
Magnesium
Zn
Zinc
Active Site
Location on the Enzyme where Substrates bind
dehydrogenase
removes hydrogen from substrate
decarboxylase
removes CO2 from substrate
Apoenzyme
the inactive, protein portion of an enzyme
Holoenzyme
an active, functional enzyme
apoenzyme + cofactor = holoenzyme
holo-
whole
Ca
Calcium
Cofactor Critical for Blood Clotting
Ca (calcium)
4 Factors Affecting Enzymatic Activity
- pH
- temp
- substrate concentration
- chemical inhibitors
(i.e. competetive and noncompetetive inhibition)
What affect can pH have on enzymes?
If the pH is too high or too low, the enzyme can denture
denature
loss of a protein’s 3D structure caused by temp or changes in pH
Structure determines ________.
Function
Function determines _______.
Structure
Biochemical Pathways
Multistep chemical reactions that require the use of multiple enzymes.
i.e the conversion of glucose into pyruvate in glycolysis is a 10-step process that requires 10 different enzymes to catalyze each reaction.
How do high temperatures denature a protein?
High temps break the hydrogen bonds that give protein a 3D structure.
Do cold temps denature proteins?
No, they just decrease the enzymatic activity.
Decreased Temp = Decrased Kinetic E –> Decreased Activity
What is kinetic energy?
the energy of motion
Describe the Levels of Protein Structure
Primary: strand of amino acids connected
Secondary: alpha-helices and beta-sheets
Tertiary Structure: 3D Globular Structure
Quaternary Structure: multiple proteins clustered together
What affect do colder temperatures have on enzymes?
Colder temperatures lower the Kinetic Energy (movement of molecules) and consequently slows down enzymatic activity.
optimum pH
the pH at which an enzyme is most active
Different types of enzymes have different optimum pHs.
Optimum pH of Pepsin (found in the stomach)
2
Optimum pH of Salivary Amylase
7
Optimum pH of Trypsin
10
Saturation Point
The point at which the enzymes are working at full capacity and adding more substrate will not increase how fast the reaction takes place.
Competetive Inhibitors
have a similar stuctures to the substrates and can bind to the active site of the enzyme preventing the substrate from binding
analog
molecules with similar structures
Para Amio Benzoic Acid
PABA
molecule used to produce folic acid
Sulfonamide
competethive Inhibitor of PABA.
When sulfonamide binds to the active site instead of PABA, no rxn takes place and therefore no folic acid is produced.
Allosteric Inhibition
A non-competetive inhibitor binds to the Allosteric Site on an Enzyme causing the shape of the enzyme to change.
Because structure determines function, when the shape of the enzyme (including the active site) changes it can no longer function to bind and react substate.
2 Types of Non-Competetive Inhibition of an Enzyme
- Allosteric Inhibition
- Removal of the Cofactor
Glycolysis
the breakdown of glucose into 2 molecules of pyruvate
Reduction Rxn
an electron is gained
Oxidation Rxn
an electron is lost
Reduction vs Oxidation
LEO the lion says GER
LEO: Loses Electrons = Oxidation
GER: Gains Electrons = Reduction
OR
OIL RIG
Oxidation is Losing e-
Reduction is Gaining e-
NAD+ –> NADH
reduction
FAD –> FADH2
reduction
NADH –> NAD+
oxidation
FADH2 –> FAD
oxidation
Adding Hydrogens indicates Oxidation or Reduction?
Reduction
Removing Hydrogens indicates Oxidation or Reduction?
Oxidation
oxidative phosphorylation
as one molecule is oxidized another is phosphorylated
Number of Carbons in Glucose
6
Number of Carbons in Pyruvate
3
What is the Net ATP synthesized in Glycolysis?
2
(4 ATP total is produced, but 2 ATP are used in the process. 4-2=2, so the Net ATP production is 2.)
Glycolysis is part of both _____ and _______.
Cellular Respiration & Fermentation
Where does Glycolysis take place?
the cytosol
Where does the preparatory rxn converting Pyruvate into Acetyl CoA take place?
the cytosol
Citric Acid Cycle AKA
the Krebs Cycle
Where does the citric acid cycle occur in a eukaryotic cell?
the matrix of the mitochondria
Transition Rxn AKA
the Preparatory Rxn
What is the Transition Rxn?
Converts Pyruvate into Acetyl Coenzyme A (Acetyl CoA)
What are the Products of the Krebs’s Cycle?
4 CO2
6 NADH
2 FADH2
2 ATP
NAD+ is _______ to form NADH.
reduced
FAD is _______ to form FADH2.
reduced
What type of rxn is taking place in the Electron Transport Chain?
Oxidative Phosphorylation
NADH is ________ to form NAD+.
oxidized
FADH2 is ______ to form FAD.
oxidized
Location of the Electron Transport Chain in a Prokaryote
plasma membrane
Location of the Electron Transport Chain in a Eukaryote
inner mitochondrial membrane
What happens to the NADH and FADH2 produced during the Citric Acid Cycle?
they go to the electron transport chain to fuel the proton gradient which generates more ATP
What is the purpose of the Citric Acid Cycle?
Acytle CoA (2C) is combined with oxaloacetate (4C) to form Citrate (6C). Through a series of steps the carbons are broken down into CO2 and E is extracted in the form of NADH and FADH2 which can then be taken through the electron transport chain to generate more ATP.
What is the purpose of the Electron Transport Chain?
The Electron Transport Chain uses E from NADH and FADH2 to reduce O2 to H2O.
The E released when O2 is reduced to H2O shuttles H+ out of the mitochondrial matrix. The proton gradient formed allows H+ to “fall” back into the matrix via the ATP Synthase embedded in the inner membrane. This falling motion allows the subunits of ATP synthase to rotate and convert ADP into ATP.
_____ is the terminal electron acceptor in the electron transport chain.
O2
(oxygen)
What is the total # of ATP produced in cellular respiration?
38 in prokaryotes
36 in eukaryotes
Anaerobic Respiration
the terminal electron acceptor is NOT oxygen
Terminal Electron Acceptor in Denitrifying Bacteria
Nitrate (NO3-)
2 Major Types of Fermentation
Lactic Acid Fermentation
Alcohol Fermentation
Name 2 Bacterias that can do Lactic Acid Fermentation
Lactobacillus & Streptococcus
Name 2 Microorganisms that can do Alcohol Fermentation
Yeast & Clostridum
Saccharomyces
Genus of Yeast
