Chapter 6 - Principles of Metabolism Flashcards
What is catabolism?
A process that harvests energy released during the breakdown of compounds such as glucose, using it to synthesize ATP
What is Anabolism?
A process that utilizes energy stored in ATP to synthesize and assemble the subunits of macromolecules that make up the cell; Biosynthesis
What is an exergonic reaction?
A reaction that releases energy
What is an endergonic reaction?
A reaction that consumes energy
What is an oxidation reaction?
a
What is a reduction reaction?
a
What is a dehydrogenation reaction?
a
What is a hydrogenation reaction?
a
Describe Substrate-level phosphorylation.
a
Describe oxidative phosphorylation.
a
Describe photophosphorylation.
a
What are enzymes and how are they named?
They are biological catalysts that has a name that reflects its function and ends in -ase
What is an active site?
The place where a substrate binds on an enzyme
Are enzymes highly specific?
Yes
Is an enzyme used up in the catalytic process?
no
What happens when a substrate binds to an active site?
The enzyme changes shape slightly
What is the term for the role of enzymes?
Biological catalysts
What do enzymes do?
Speed up conversion of substrate into product by lowering activation energy
What do cofactors do?
Assist different enzymes
What are some examples of cofactors?
magnesium, zinc, copper, other trace elements
What is an example of coenzymes?
FAD, NAD+, NADP+, many are vitamin derived
What factors influence enzyme activity?
Temperature, pH, salt concentration
How much of an increase in speed of enzymatic reactions is seen in an increase of 10˚C?
It doubles the speed
What happens to proteins at high temperatures?
They are denatured
True or False? Low salt and neutral pH are usually optimal.
True
What does a competitive inhibitor do?
It binds to the active site and blocks the substrate
What is a characteristic of a competitive inhibitor?
They have chemical structures close to that of the substrate
What do non-competitive inhibitors do?
Bind to sites other than the active site and alter shape or function
What is an allosteric inhibitor?
one thats action is reversible, usually seen at enzyme a, the first, and allows feedback inhibition
What is a poison of non-competitive inhibition?
mercury, cystine, and the enzyme changes shape and becomes nonfunctional
What are possible energy sources for prokaryotes?
Sunlight, organic compounds (glucose, polysaccharides, proteins, lipids), and Inorganic compounds (H2S, NH3)
How is energy harvested from chemicals through respiration and fermentation?
Through removing electrons from series of oxidation-reduction reactions or redox reactions
What is reducing power?
electrons easily transfer to molecules, raising energy of recipient molecule
What are some Electron carriers?
NAD+/NADH, NADP+/NADPH, FAD/FADH2
What is the difference between NADH and FADH2 and NADPH
NADH and FADH2 are used to drive proton motive force for ATP synthesis and NADPH is used in biosynthesis
How is energy provided inSubstrate-level phosphorylation?
exergonic reactions provide energy
What is Oxidative phosphorylation?
Proton motive force from ETC
What is Photophosphorylation?
sunlight used to create proton motive force
What are precursor metabolites?
intermediates of catabolism that can be used in anabolism
What is the formula for Aerobic Respiration of Glucose?
C6H12O6 + 6O2 –> 6CO2 + 6H2O + 38 ATP
What steps are taken in aerobic respiration of glucose?
- Glycolysis/Pentose phosphate pathway
- a) Transition Step b) Tricarboxylic Acid Cycle (TCA)/Krebs cycle
- Electron Transport Chain (O2 terminal e- acceptor)
True or False? Glycolysis only takes place aerobically.
False, it takes place anaerobically and aerobically
What does glycolysis produce?
2 ATP, 2 Reducing agents (2NADH + 2H+), and 6 precursor metabolites (5 intermediates of glycolysis as well as pyruvate, used by E. coli)
Where does the transition step take place?
the cytoplasm of bacteria
What are the end products of the transition step?
2 Acetyl CoA, 2 CO2, and 2 NADH
What does the TCA cycle complete?
the oxidation of glucose
What does the TCA cycle produce?
4 CO2, 2 ATP (substrate level), 6 NADH, 2 FADH2, and precursor metabolites
Who proposed the process of the Electron Transport Chain?
Peter Mitchell
What is the theory called today?
The chemiosmotic theory
What is the electron transport chain?
membrane-embedded electron carriers
Where does the ETC take place in prokaryotes?
The cytoplasmic membrane
Where does the ETC take place in eukaryotes?
The mitochondrial membrane
What is a characteristic of ubiquinone?
It can move freely in the membrane
What are the components of the ETC and their functions?
Quinones - lipid soluble molecules that move freely and transfer electrons between complexes
Cytochromes - contain heme, molecule with iron at center and there are several types
Flavoproteins - proteins to which a flavin is attached, FAD, other flavins synthesized from riboflavin
How many protons are needed to form one ATP?
3
How many ATP are made from each electron pair from NADH?
3
How many ATP are made from each electron pair from FADH2?
2
Fill in the blanks:
Glycolysis: \_\_NADH-->\_\_ATP
Transition Step: \_\_NADH-->\_\_ATP
TCA cycle: \_\_NADH-->\_\_ATP
\_\_FADH2-->\_\_ATP
Total yield form oxidative phosphorylation: \_\_ATP2, 6 2, 6 6, 18 2, 4 34
Fill in the blanks for Substrate Level Phosphorylation: \_\_ATP from glycolysis; net gain \_\_ATP from TCA cycle ----------------------------------- \_\_ATP total
2
2
4
What changes in anaerobic respiration?
inorganic compounds are used as final electron acceptors
What can serve as final electron acceptors in anaerobic respiration?
NO3, SO4, CO3 and produce N2, H2S
How many ATP are produced by anaerobic respiration?
Average of 32-34 ATP
Fill in the blanks:
Anaerobic respiration harvests ____ energy from glucose than aerobic respiration but ____ energy than fermentation.
Less, More
Describe the catabolism of polysaccharides and disaccharides.
Amylases digest starch and cullulases digest cellulose
Describe the catabolism of lipids.
They are hydrolyzed by lipases, and glycerol is converted to dihydroxyacetone phosphate, which enters glycolysis
Fatty acids are degraded by B-oxidation to enter TCA cycle
Describe the catabolism of Proetins.
Hydrolyzed by proteases and the amino group is deaminated
converted into precursor molecules
What are Chemolithotrophs?
prokaryotes that can use reduced inorganic compounds as sources of energy (H2S, NH3)
What are the 4 groups of chemolithotrophs?
- Hydrogen Bacteria
- Sulfur bacteria
- Iron bacteria
- Nitrifying bacteria
When does fermentation happen?
when respiration is not an option
What is special about E. coli?
it can undergo aerobic respiration, anaerobic respiration, and fermentation
What is special about Streptococcus pneumoniae?
It lacks an electron transport chain
What pathways can pyruvate go into in fermentation?
Lactic acid, ethanol, butyric acid, propionic acid, mixed acids, and 2,3-butanediol
What are end products of Lactic acid ?
What organisms use this?
lactic acid
streptococcus and lactobacillus
What are end products of Ethanol ?
What organisms use this?
ethanol, CO2
saccharomyces
What are end products of Butyric acid ?
What organisms use this?
butyric acid, butanol, acetone, isopropanol, CO2, H2
clostridium
What are end products of Propionic acid ?
What organisms use this?
propionic acid, acetic acid, CO2
propionibacterium
What are end products of Mixed acids ?
What organisms use this?
acetic acid, lactic acid, succinic acid, ethanol, CO2, H2
E. coli
What are end products of 2,3-Butanediol ?
What organisms use this?
CO2, H2
Enterobacteriacea
