1) Energy can be transferred and stored in cells in the form of: a) Chemical gra
ID: 56455 • Letter: 1
Question
1) Energy can be transferred and stored in cells in the form of:
a) Chemical gradients
b) Electrical gradients
c) Phosphate groups
d) Electrons
e) Hydrogen atoms
f) All of the above
2) Which of the following terms is used to describe the change in the shape of an enzyme following substrate attachment?
a) Substrate binding flexion
b) Induced fit
c) Conformational shift
d) Substrate forcing
e) Paradigm shift
3) In humans, DOPA is both a precursor of melanin in skin and of dopamine, a central nervous system neurotransmitter. What likely determines the fate of DOPA in skin cells as compared to nerve cells (ie: whether DOPA will become melanin or opamine):
a) Quantity of DOPA
b) Quantity of tyrosine
c) The quantity of tyrosinase present
d) The presence of different enzymes and later steps of metabolic pathways
Explanation / Answer
1) Energy can be transferred and stored in cells in the form of:
a) Chemical gradients
b) Electrical gradients
c) Phosphate groups
d) Electrons
e) Hydrogen atoms
Ans: All of the above.
Ans:A)according to the chemiosmatic theory electrochemical gadiant is created for the production of ATP.
B)electrons and hydrogens in the form of H+ Protons invoved in the electron transport chain to produce ATP.
C)enegry is stored in the terminal phosphate of the ATP.
2) Which of the following terms is used to describe the change in the shape of an enzyme following substrate attachment?
b) Induced fit
explanation:
Changes in Structure During the Induced Fit
The basis of chemical reactions is a change in atom arrangement and bonds between atoms. When the substrate interacts with the enzyme it undergoes a chemical reaction that allows the atoms to move relative to each other, the bonds to possibly lengthen or shorten and the most reactive groups to move closer to each other, causing a shape change. This shape change makes the substrate more amenable to alteration, as it holds the substrate in a transitional state, which helps speed up the reaction that that enzyme catalyzes.
Advantages of the Induced Fit Model
With the induced fit model, the way that the substrate has to change its structure may be useful in terms of the catalysis itself. It may represent the beginning of the reaction that the enzyme is catalyzing. Conversely, in the lock and key model, the catalysis follows after the substrate fits into the enzyme.
3) In humans, DOPA is both a precursor of melanin in skin and of dopamine, a central nervous system neurotransmitter. What likely determines the fate of DOPA in skin cells as compared to nerve cells (ie: whether DOPA will become melanin or opamine):
ans: The quantity of tyrosinase present
explanation:
Tyrosinase is an oxidase that is the rate-limiting enzyme for controlling the production of melanin. It is mainly involved in two distinct reactions of melanin synthesis; firstly, the hydroxylation of a monophenol and secondly, the conversion of an o-diphenol to the corresponding o-quinone. o-Quinone undergoes several reactions to eventually form melanin
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