1. Gated ion channels: (multiple choice) A) Opens only when there is a 104 diffe
ID: 149539 • Letter: 1
Question
1. Gated ion channels: (multiple choice)
A) Opens only when there is a 104 difference in ion concentration across a membrane.
B) Requires an input of energy to transport an ion across a membrane.
C) Generates an ion gradient.
D) Can transport any type of positive ion through the same channel.
E) All of the above are false.
True of False
2. Archaebacteria, many of which live in extreme environments such as deep sea vents, are more closely related to Eukaryote cells than are Eubacteria such as E. coli, which live in the human gut.
explain both of these please
Explanation / Answer
1. Gated ion channels are broadly classified broadly into two types: Ligand-gated and Voltage-gated. Ligand-gated ion channels do not need a difference in potential across a membrane, it requires a ligand for its opening. Also, For nerve impulse transmission, the threshold membrane potential Voltage-gated Na+ channel to open is -55mV. Hence, Option "a" is incorrect.
Gated ion channels do not require any energy(ATP) for its functioning, it either requires a ligand or a difference in membrane potential. Hence, option B is incorrect.
Gated ion channels do not generate an ion gradient, they transport ions down the electrochemical gradient. Generation of ionic gradient requires ATP which such channels do not need.
Gated ion channels are highly specific. The channels through which the ions pass are adjusted to the size of the ion for which that channel is specific. Hence, they cannot transport any type of positive ion through the same channel.
From the above statement, it is clear that option E "All of the above are false." is Correct.
2. True.
Archaebacteria, living in extreme environments are not placed under prokaryotes or under eukaryotes. They appear like prokaryotes and were originally classified as bacteria (hence the name), but later it was discovered that such organisms had genes that are more closely related to eukaryotes. Molecular phylogeny, which relies greatly on the sequences of rRNA to determine the relationships between organism, suggests that Archaebacteria have sequences that are similar to that of eukaryotes. But, Archaebacteria has no membrane-bound organelle. This is why they have been classified under an entirely different domain 'ARCHEA'.
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