Lecture 16 - Mem. I Flashcards

1
Q

Biological membranes are easily dissociable due to______

A

Non-covalent bonding between phospholipids.

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2
Q

What is meant by the “fluid structure” of a membrane?

A

Lipids readily diffuse LATERALLY, but do not flip from inner to outer leaflets (or vice versa).

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3
Q

Describe how micelles are important to biological f(x).

A

Polar head groups face aqueous environment. The fatty acid tails produce an environment that can “dissolve,” or surround, hydrophobic molecules, like fats.

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4
Q

Most phospholipids form a bilayer instead of a micelle. Why?

A

Though both are driven by hydrophobic forces, most phospholipid fatty acid tails are too bulky to fit in a micelle interior (most micelles

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5
Q

Between FA tails, there are _______ interactions.

A

van der Walls

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6
Q

There are _____ and _____ forces between water and polar heads.

A

Hydrogen bonding; electrostatic

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7
Q

Hydrophobic interactions lead to these three “major consequences” in membrane formation.

A

1) lipid membranes are extensive
2) membranes close on themselves
3) membranes are self sealing (E* favorable)

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8
Q

The cholesterol ring structure produces (increased fluidity/stiffness) in a plasma membrane.

A

Stiffness

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9
Q

The hydrocarbon tail associated with a cholesterol molecule produces (fluidity/stiffness) of a membrane.

A

Fluidity (hydrophobic interactions)

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10
Q

In plasma membrane permeability (w/o any channels/transporters), what molecules readily diffuse?

A

Water (small, no net charge, high [ECF])

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11
Q

In plasma membrane permeability (w/o any channels/transporters), what molecules do not readily diffuse?

A

Large, charged molecules

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12
Q

Integral membrane proteins 1* interact with the PM by _______.

A

Hydrophobic interactions.

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13
Q

Integral membrane proteins can be removed from the PM by _______.

A

Dissociation of the membrane through detergents (disrupts Hydrophobic interactions).

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14
Q

Peripheral proteins are bound to the membrane by _____ and ______ interactions.

A

Electrostatic; hydrogen-bond

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15
Q

Peripheral proteins are dissociated from the membrane by ____ and _____.

A
  • pH changes (changes the side chains of the AAs interacting with polar heads)
  • salts (interact with the water in solution, causing dissociation and “salting out”)
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16
Q

Why are alpha helices the most common membrane spanning motif?

A

Alpha helices are very flexible (important in the fluid/pliable PM) and have OUTWARD facing hydrophobic R groups due to the helix

17
Q

These proteins are covalently linked to the PM.

A

Lipid linked proteins

18
Q

Phospholipids that are bound to proteins via sugar linkages.

A

GPI (glycosyl phosphotidylinositol) linked proteins

19
Q

What critical membrane proteins are found attached by GPI linkages?

A

Cell adhesion molecules

20
Q

Location of oxidative phosphorylation in the mitochondria.

A

Inner mitochondrial membrane

21
Q

Site of TCA cycle and fatty acid oxidation

A

Mitochondrial matrix

22
Q

Which mitochondrial membrane is highly permeable to most ions? Why is this important?

A

Outer membrane. Important for substrates to be able to readily diffuse.

23
Q

Explain the driving force behind lipid bilayer formation.

A

The amphipathic nature of phospholipids (polar head, non-polar tail) promotes formation. The polar heads face themselves toward the aqueous environment, and fatty acid tails form a hydrophobic area.