Topic 2.2 Flashcards
Which of the following is incorrect regarding nucleotides?
a) They contain sugar, a nitrogen-containing base, and a phosphate functional group
b) They are the monomers f fats a polysaccharides
c) They join together by alternating covalent bonds between the sugars and phosphate groups
d) They are present in both DNA and RNA
b) They are the monomers f fats a polysaccharides
Which of the following is correct regarding ATP?
a) It is an amino acid
b) It has a heliccal structure
c) It is a high- energy molecule that can break down to ADP and phosphate
d) It is a nucleotide component o DNA and RNA
c) It is a high- energy molecule that can break down to ADP and phosphate
Summarize why enzymes are needed in biochemical pathways and how cells may regulate their activity
*Enzymes are needed to reduce the activation energy of the reactions present in a biochemical reaction, this allowing reactions to occur under conditions of the cell.
*A cell can convert an enzyme from an inactive form to an active one by the addition or removal of phosphate groups or by cleaving off parts of the protein
*Cellular enzymes are subject to feedback inhibition.
*The presence of cofactors and coenzymes in the cell regulates enzyme activity
Describe how enzymes accelerate chemical reactions
Enzymes lower the activation of a reaction, allowing it to occur with lower inputs of energy
Discuss why the three-dimensional shape of an enzyme is important to its function
How well the enzyme interacts with the reactants and the rate at which product is formed is determined by the three- dimensional shape of the protein molecule and its active site
Define metabolic pathway
Series of linked reactions, beginning with a particular reactant and terminating with an end product.
Define enzyme
Organic catalyst, usually a protein, that speeds a reaction in cells due to its particular shape.
Define ribozomes
RNA molecule that functions as an enzyme that can catalyze chemical reactions.
Define energy of activation (Ea)
Energy that must be added in order for molecules to react with one another.
Define active site
Region of an enzyme where the substrate binds and where the chemical reaction occurs.
Define induced fit model
Change in the shape of an enzyme’s active site that enhances the fit between the active site and its substrate(s).
Define denatured
Loss of a protein’s or enzyme’s normal shape so that it no longer functions; usually caused by a less than optimal pH and temperature.
Define enzyme inhibition
Means by which cells regulate enzyme activity; may be competitive or noncompetitive inhibition.
Define cofactor
Nonprotein assistant required by an enzyme in order to function. Many cofactors are metal ions; others are coenzymes.
Define coenzymes
Nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound.
Define vitamin
Organic nutrient that is required in small amounts for metabolic functions. Vitamins are often part of coenzymes.
Which of the following is incorrect regarding the active site of an enzyme?
a) is unique to that enzyme
b) is the part of the enzyme where its substrate fits in
c) can be used over and over again
d) is not affected by environmental factors, such as pH and temperature
d) is not affected by environmental factors, such as pH and temperature
Which of the following environmental conditions may have an influence on enzyme activity?
a) substrate concentration
b) temperature
c) pH
d) all of the above
d) all of the above
In which of the following does an inhibitor bind to a site other than the active site of an enzyme?
a) competitive inhibition
b) noncompetitive inhibition
c) redox reactions
d) none of the above
d) none of the above
Enzymes catalyze chemical reactions by which of the following?
a) lowering the energy of activation in the reaction
b) raising the energy of activation in the reaction
c) increasing entropy
d) increasing the free energy of the products
b) raising the energy of activation in the reaction
Enzymes catalyze chemical reactions by which of the following?
a) lowering the energy of activation in the reaction
b) raising the energy of activation in the reaction
c) increasing entropy
d) increasing the free energy of the products
a) lowering the energy of activation in the reaction
Explain the role of NAD+ and FAD in cellular respiration
NAD+ and FAD serve as coenzymes for the enzymes involved in cellular respiration. Both molecules receive electrons and become reduced (NADH and FADH2) and transport the electrons to inside the mitochondria, where they function in the electron transport chain.
Distinguish between the aerobic and anaerobic phases of cellular respiration
Glycolysis is an anaerobic process. The preparatory reaction, citric acid cycle (KREBS cycle), and electron transport chain are all aerobic and therefore dependent on the presence of oxygen.
Summarize the location and function of each phase of cellular respiration
The complete breakdown of glucose during cellular respiration consists of four phases:
1. Glycolysis in the cytoplasm produces pyruvate, which enters mitochondria if oxygen is available.
2. The preparatory reaction and the citric acid cycle that follow occur inside the mitochondria.
3. Inside the mitochondria, the electron transport chain receives the electrons removed from glucose breakdown products.
4. The result of glucose breakdown is a maximum of 36 to 38 ATP, depending on the particular cell.
Glycolysis~>Preparatory reaction/Krebs cycle~>Electrons received in electron transport chain~>Glucose breakdown= 36 to 38 ATP
Define cellular respiration
Metabolic reactions that use the energy from carbohydrate, fatty acid, or amino acid breakdown to produce ATP molecules.
Define NAD+ (Nicotinamide adenine dinucleotide)
Coenzyme in oxidation-reduction reactions that accepts electrons and hydrogen ions to become NADH + H+ as oxidation of substrates occurs. During cellular respiration, NADH carries electrons to the electron transport chain in mitochondria.
Define FAD (flavin adenine dinucleotide)
A coenzyme of oxidation-reduction that becomes FADH2 as oxidation of substrates occurs in the mitochondria during cellular respiration, FAD then delivers electrons to the electron transport chain.
Define anaerobic
A chemical reaction that occurs in the absence of oxygen; an example is the fermentation reactions.
Define aerobic
A chemical process that requires air (oxygen); phase of cellular respiration that requires oxygen.
During glycolysis, what is the net production of ATP per glucose molecule?
a) 0
b) 1
c) 2
d) 8
e) 32-34
c) 2
Which of the following is not a product or reactant of glycolysis
a) NADH
b) ATP
c) pyruvate
d) oxygen
d) oxygen
Which of these is incorrect regarding fermentation?
a) There is a net gain of only two ATP per glucose
b) It occurs in the cytoplasm
c) The process starts with glucose entering glycolysis
d) NADH donates electrons to the electron transport chain
e) it’s anaerobic
d) NADH donates electrons to the electron transport chain
Fermentation is primarily involved in the recycling of
a) ADP
b) oxygen
c) pyruvate
d) NAD+
d) NAD+
The greatest contributor of electrons to the electron transport chain is
a) oxygen
b) the prep reaction
c) glycolysis
d) fermentation
e) the citric acid cycle
e) the citric acid cycle
Which of these is not true of the citric acid cycle?
a) the citric acid cycle include the prep reaction
b) the citric acid cycle produces ATP by substrate-level ATP synthesis
c) the citric acid cycle occurs in the mitochondria
d) the citric acid cycle produces two ATP per glucose molecule
a) the citric acid cycle include the prep reaction
Which of these is not true of the electron transport chain?
a) the electron transport chain is located on the cristae of the mitochondria
b) the electron transport chain produces more NADH than any metabolic pathway
c) the electron transport chain contains cytochrome molecules
d) the electron transport chain ends when oxygen accepts electrons
b) the electron transport chain produces more NADH than any metabolic pathway
The oxygen required by cellular respiration is reduced and becomes part of which molecule?
a) ATP
b) pyruvate
c) H2O
d) CO2
c) H2O
