BCH 351 FINAL EXAM QUESTIONS WITH VERIFIED
ANSWERS
What are metabolites? - Answers - - Small molecular intermediates in the degradation
or biosynthesis of biopolymer.
- These metabolites can be the substrates, reaction intermediates, or the products of a
given metabolic pathway.
Catabolic Reactions - Answers - Complex molecules are broken down to simpler ones
and energy is released.
* Converts Carbohydrates, lipids, and proteins to CO2, H2O, and NH3
* This ATP produced will drive the anabolic reaction.
Anabolic Reaction - Answers - A synthetic reaction in which simple molecules are linked
to form more complex ones; requires an input of energy and captures it in the chemical
bonds that are formed.
* Converts Amino acids, sugars, fatty acids, & nitrogenous bases to proteins,
polysaccharides, lipids, and nucleic acids.
* The ATP is consumed.
What are the Characteristics of Metabolic Pathways? - Answers - 1. Metabolic pathways
are sequences of reactions.
2. Metabolic pathways proceed by discrete steps.
3. Metabolic pathways are regulated.
4. Metabolic pathways are compartmentalized.
1. Metabolic pathways are sequences of reactions. - Answers - - The product of one
reaction serves as substrate for the next reaction.
- A pathway may be only two or many sequential reactions.
- Linear, circular, and spiral.
Linear Pathway - Answers - - Linear pathways utilize intermediates from other pathways
or branch to make different products but proceed in a linear direction to synthesize end
products form precursor substrates or pathway intermediates.
Examples: Glycolysis and Oxidative phosphorylation
Circular Pathway - Answers - - Goes in a circular fashion with the product produced
ultimately becoming the initial substrate.
, - In the cycle other substrates from other pathways are often utilized and frequently
some intermediates produced in the circle pathway leave the cycle as products.
Examples: TCA cycle and urea cycle.
Spiral Pathway - Answers - - Often the same enzyme is used to catalyze the
subsequent reaction to produce an enlarged or elongated product.
- This pathway is most frequently used for building biopolymers such as lipids, nucleic
acids, proteins, and polysaccharides.
Examples: Lipid, DNA, RNA, biosynthesis.
2. Metabolic pathways proceed by discrete steps. - Answers - - Each step (specific
reaction) is catalyzed by a specific enzyme.
- Multiple steps help to control energy input and output
- Sharing of intermediates between pathways.
3. Metabolic pathways are regulated. - Answers - - Regulation of enzyme activity is
essential; for the efficiency and the ordered flow of metabolism.
- Enzymes can be regulated through:
- Substrate level control
- Regulation at committed steps of pathways: (feedback inhibition, feedforward
activation, allosteric regulation)
- Covalent modification
4. Metabolic pathways are compartmentalized - Answers - - Many metabolic pathways
are located within specific regions, organelles, or membranes of the cell.
- There are advantages
The advantages of metabolic pathways - Answers - - Pools of metabolites for specific
pathways are localized and concentrated.
- Location of different metabolic pathways at different sites allow opposing metabolic
pathways to occur at the same time.
- Specific location of a metabolic pathway allows coordinated regulation of the individual
reactions.
- Specific localization of metabolic pathway allows spatial organization of a sequence of
reactions.
- Specialization of tissues allow division of labor and for better efficiency and site
specific regulation.
The thermodynamics of metabolic reactions - Answers - - The Gibbs free energy is a
measure of the energy available of a reaction at equilibrium.
- At standard conditions the thermodynamics of a reaction at equilibrium is described as
delta G^o' reaction = deltaf G^o' products - deltaf G^o' reactants.
- Metabolic reactions in the living cells are not at standard conditions nor equilibrium.
ANSWERS
What are metabolites? - Answers - - Small molecular intermediates in the degradation
or biosynthesis of biopolymer.
- These metabolites can be the substrates, reaction intermediates, or the products of a
given metabolic pathway.
Catabolic Reactions - Answers - Complex molecules are broken down to simpler ones
and energy is released.
* Converts Carbohydrates, lipids, and proteins to CO2, H2O, and NH3
* This ATP produced will drive the anabolic reaction.
Anabolic Reaction - Answers - A synthetic reaction in which simple molecules are linked
to form more complex ones; requires an input of energy and captures it in the chemical
bonds that are formed.
* Converts Amino acids, sugars, fatty acids, & nitrogenous bases to proteins,
polysaccharides, lipids, and nucleic acids.
* The ATP is consumed.
What are the Characteristics of Metabolic Pathways? - Answers - 1. Metabolic pathways
are sequences of reactions.
2. Metabolic pathways proceed by discrete steps.
3. Metabolic pathways are regulated.
4. Metabolic pathways are compartmentalized.
1. Metabolic pathways are sequences of reactions. - Answers - - The product of one
reaction serves as substrate for the next reaction.
- A pathway may be only two or many sequential reactions.
- Linear, circular, and spiral.
Linear Pathway - Answers - - Linear pathways utilize intermediates from other pathways
or branch to make different products but proceed in a linear direction to synthesize end
products form precursor substrates or pathway intermediates.
Examples: Glycolysis and Oxidative phosphorylation
Circular Pathway - Answers - - Goes in a circular fashion with the product produced
ultimately becoming the initial substrate.
, - In the cycle other substrates from other pathways are often utilized and frequently
some intermediates produced in the circle pathway leave the cycle as products.
Examples: TCA cycle and urea cycle.
Spiral Pathway - Answers - - Often the same enzyme is used to catalyze the
subsequent reaction to produce an enlarged or elongated product.
- This pathway is most frequently used for building biopolymers such as lipids, nucleic
acids, proteins, and polysaccharides.
Examples: Lipid, DNA, RNA, biosynthesis.
2. Metabolic pathways proceed by discrete steps. - Answers - - Each step (specific
reaction) is catalyzed by a specific enzyme.
- Multiple steps help to control energy input and output
- Sharing of intermediates between pathways.
3. Metabolic pathways are regulated. - Answers - - Regulation of enzyme activity is
essential; for the efficiency and the ordered flow of metabolism.
- Enzymes can be regulated through:
- Substrate level control
- Regulation at committed steps of pathways: (feedback inhibition, feedforward
activation, allosteric regulation)
- Covalent modification
4. Metabolic pathways are compartmentalized - Answers - - Many metabolic pathways
are located within specific regions, organelles, or membranes of the cell.
- There are advantages
The advantages of metabolic pathways - Answers - - Pools of metabolites for specific
pathways are localized and concentrated.
- Location of different metabolic pathways at different sites allow opposing metabolic
pathways to occur at the same time.
- Specific location of a metabolic pathway allows coordinated regulation of the individual
reactions.
- Specific localization of metabolic pathway allows spatial organization of a sequence of
reactions.
- Specialization of tissues allow division of labor and for better efficiency and site
specific regulation.
The thermodynamics of metabolic reactions - Answers - - The Gibbs free energy is a
measure of the energy available of a reaction at equilibrium.
- At standard conditions the thermodynamics of a reaction at equilibrium is described as
delta G^o' reaction = deltaf G^o' products - deltaf G^o' reactants.
- Metabolic reactions in the living cells are not at standard conditions nor equilibrium.
