Membranes and Membrane transport Flashcards

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1
Q

The cytosol of nearly all prokaryotes is surrounded by a phospholipid bilayer called

A

plasma mem .

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2
Q

What is phospholipid?

A

phosphate group, two FA chains, and a glycerol backbone.
this molecule is amphipathic ( has a polar and a non polar portion)
micelles can form with phospholipids
(bc they are the most thermodynamically stable conformation) and if enough are present ..liposomes

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3
Q

unlike eukaryotic membranes, prokaryotic plasma membranes usually do not have steroids like ?

A

cholesterol

instead some bacterial mem contain steroid like molecules called hapanoids

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4
Q

Membrane proteins act as ..

A
transporters
receptors 
attachment sites 
identifiers 
adhesive proteins and enzymes
some membrane proteins are attachment sites that anchor the cytoskeleton.
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5
Q

adhesion by one cell to another is accomplished by?

A

mem proteins

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6
Q

integral or intrinsic proteins are..?

A

amphipathic

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7
Q

what are the forces that hold the membrane together?

A

intermolecular forces ! the mem is therefore fluid . (parts can move laterally )
the model is described as a fluid mosaic model.

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8
Q

in eukaryotic membranes what moderates the mem fluidity?

A

cholesterol.

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9
Q

in prokaryotic membranes what reduces the fluidity?

A

hapanoids

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10
Q

what is the chemical concentration gradient?

A

pointing in the direction of lower concentration

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11
Q

what is the electrical concentration gradient?

A

where a positively charged particle will move.

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12
Q

what are two aspects of a compound that affect its semipermeability ?

A

size and polarity.
larger molecule - less permeable .
polarity- greater polarity (charge) = less permeable the mem is to the molecule

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13
Q

passive diffusion

A

molecules move through leakage channels across the mem due to random motion

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14
Q

transport or carrier proteins

A

facilitate the diffusion of specific molecules across the mem.
in order for a passage to be considered facilitated diffusion, diffusion must occur down the electro-chemical gradient.

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15
Q

active transport

A

movement of compound against its electrochemical gradient

expenditure of energy is needed.

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