Membrane Proteins Flashcards

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1
Q

Regions of hydrophobic R groups allow

A

strong hydrophobic interactions that hold integral proteins within the phospholipid bilayer

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2
Q

Some integral proteins are

A

transmembrane

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3
Q

What are peripheral membrane proteins?

A

Have hydrophilic R groups on their surface and are bound to the surface of membranes, mainly by ionic and hydrogen bond interactions

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4
Q

The phospholipid bilayer is a barrier to

A

ions and most uncharged polar molecules

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5
Q

Some small molecules, such as oxygen and carbon dioxide

A

pass through the phospholipid bilayer by simple diffusion

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6
Q

What is facilitated diffusion?

A

The passive transport of substances across the membrane through specific transmembrane proteins

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7
Q

What do different cell types have in order to perform specialised functions?

A

different channel and transporter proteins

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8
Q

Most channel proteins in animal and plant cells are ________ selective

A

highly

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9
Q

Some channel proteins are gated and change conformation to

A

allow or prevent diffusion

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10
Q

What are ligand-gated channels controlled by?

A

the binding of signal molecules

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11
Q

What are voltage-gated channels controlled by?

A

changes in ion concentration

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12
Q

Transporter proteins bind to the

A

specific substance to be transported and undergo a conformational change to transfer the solute across the membrane

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13
Q

Active transport uses

A

pump proteins that transfer substances across the membrane against their concentration gradient

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14
Q

What is required for active transport?

A

A source of metabolic energy

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15
Q

Some active transport proteins hydrolyse ATP directly, to

A

provide the energy for the conformational change required to move substances across the membrane

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16
Q

What does ATPase do?

A

hydrolyse ATP

17
Q

What is the electrochemical gradient?

A

A combination of the concentration gradient and the electrical potential difference

18
Q

What does the electrochemical gradient do?

A

determines the transport of the solute

19
Q

What do ion pumps (eg the sodium-potassium pump) use energy from the hydrolysis of ATP to do?

A

To establish and maintain ion gradients

20
Q

The sodium-potassium pump actively transports

A

sodium ions out of the cell and potassium ions into the cell

21
Q

The pump has high affinity for

A

sodium ions inside the cell; binding occurs; phosphorylation by ATP; conformation changes; affinity for sodium ions decreases; sodium ions released outside of cells, potassium ions bind outside the cell; dephosphorylation ;conformation changes; potassium ions taken into cell; affinity returns to start

22
Q

In the small intestine, the concentration gradient of sodium ions created by the sodium-potassium pump

A

drives the active transport of glucose

23
Q

The sodium potassium pump is found in

A

most animal cells

24
Q

The sodium-potassium pump accounts for a

A

high proportion of the basal metabolic rate in many organisms

25
Q

The glucose transporter responsible for this glucose symport transports

A

sodium ions and glucose at the same time and in the same direction

26
Q

When is a membrane potential (an electrical potential difference) created?

A

when there is a difference in electrical charge on the 2 sides of the membrane

27
Q

For each ATP hydrolysed

A

3 sodium ions are transported out of the cell and 2 potassium ions are transported into the cell

28
Q

What does the transport of ions establish?

A

both concentration gradients and an electrical gradient

29
Q

Sodium ions enter the cell down their

A

concentration gradient, the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient

30
Q

What happens in intestinal epithelial cells?

A

The sodium-potassium pump generates a sodium ion gradient across the plasma membrane