A metabolic reaction with ΔG > 0 is coupled to ATP hydrolysis with ΔG = −32 kJ/mol. The metabolic reaction itself has ΔG = +20 kJ/mol under cellular conditions. What is the overall ΔG for the coupled process?
A) +52 kJ/mol
B) −12 kJ/mol
C) +12 kJ/mol
D) −52 kJ/mol
A) +52 kJ/mol
B) −12 kJ/mol
C) +12 kJ/mol
D) −52 kJ/mol
NTA EXAMINATION
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CALENDAR OUT
2026-2027 EXAMS 👇👇
https://youtube.com/shorts/C_61puord4k?si=qYVNYK_XfZU7E7y4
Membrane proteins can diffuse laterally but may show restricted movement because of:
A) Cytoskeletal attachment or extracellular matrix interactions
B) Absence of lipid molecules
C) Complete loss of membrane fluidity in all cells
D) Permanent cleavage of transmembrane helices
A) Cytoskeletal attachment or extracellular matrix interactions
B) Absence of lipid molecules
C) Complete loss of membrane fluidity in all cells
D) Permanent cleavage of transmembrane helices
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The cell membrane can maintain different protein compositions in its domains because:
A) All membrane proteins freely cross every cellular compartment
B) Diffusion barriers and selective trafficking restrict movement
C) Membrane proteins are synthesized inside the lipid bilayer
D) Proteins cannot interact with lipids
A) All membrane proteins freely cross every cellular compartment
B) Diffusion barriers and selective trafficking restrict movement
C) Membrane proteins are synthesized inside the lipid bilayer
D) Proteins cannot interact with lipids
A membrane protein that transports ions down their electrochemical gradient without ATP is most likely:
A) A primary ATPase
B) A DNA helicase
C) An ion channel or facilitated transporter
D) A ribosomal protein
A) A primary ATPase
B) A DNA helicase
C) An ion channel or facilitated transporter
D) A ribosomal protein
Ion channels differ from carrier proteins because ion channels generally:
A) Bind and chemically modify every transported ion
B) Transport molecules only against their gradients
C) Require covalent attachment of ATP to each ion
D) Provide an aqueous pathway through the membrane
A) Bind and chemically modify every transported ion
B) Transport molecules only against their gradients
C) Require covalent attachment of ATP to each ion
D) Provide an aqueous pathway through the membrane
Which statement best distinguishes channels from carriers?
A) Channels usually transport solutes through a continuous aqueous pore, whereas carriers undergo conformational cycles
B) Carriers never show substrate specificity
C) Channels always require ATP hydrolysis
D) Carriers transport only lipids and never ions
A) Channels usually transport solutes through a continuous aqueous pore, whereas carriers undergo conformational cycles
B) Carriers never show substrate specificity
C) Channels always require ATP hydrolysis
D) Carriers transport only lipids and never ions
A membrane protein contains a positively charged residue within its transmembrane region. Its presence may be explained by:
A) Complete absence of functional importance
B) Interaction with another charged residue or involvement in ion transport
C) Requirement for cellulose synthesis
D) Permanent exposure to bulk water
A) Complete absence of functional importance
B) Interaction with another charged residue or involvement in ion transport
C) Requirement for cellulose synthesis
D) Permanent exposure to bulk water
The carbohydrate portions of glycoproteins and glycolipids are generally found:
A) Only on the cytosolic surface
B) In the hydrophobic membrane core
C) Between fatty-acid tails
D) On the non-cytosolic surface of the membrane
A) Only on the cytosolic surface
B) In the hydrophobic membrane core
C) Between fatty-acid tails
D) On the non-cytosolic surface of the membrane
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Which membrane component is most directly responsible for cell–cell recognition?
A) Fatty-acid tails
B) Cholesterol rings
C) Membrane-associated carbohydrates
D) Phospholipid phosphate groups only
A) Fatty-acid tails
B) Cholesterol rings
C) Membrane-associated carbohydrates
D) Phospholipid phosphate groups only
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