Plasma Membranes Flashcards

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1
Q

Phospholipid bilayer

A

Hydrophilic phosphate polar heads
Hydrophobic fatty tails

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2
Q

Fluid mosaic model

A

Phospholipids are free to move within the later relative to each other giving flexibility and proteins embedded in bilayer vary in shape and position

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3
Q

Membrane proteins

A

Intrinsic proteins
Glycoproteins
Glycolipids
Extrinsic proteins
Cholesterol

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4
Q

Intrinsic proteins

A

Embedded through layers
Amino acids w hydrophobic R groups that interact w fatty acid tails
-Channel proteins
-Carrier proteins

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5
Q

Channel proteins

A

hydrophilic channel that allows passive movement of polar molecules down conc gradient

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6
Q

Carrier proteins

A
  • role in passive and active transport can change shape
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7
Q

Glycoproteins

A

Role in cell adhesion and receptors for chemical signals
Chemical bonds elicits a response from cell

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8
Q

Glycolipids

A

Cell markers/ antigens can be recognised by immune system as self or not self - ATTACK!

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9
Q

Extrinsic proteins

A

Present on only one side hydrophilic r groups on outer surfaces

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10
Q

Cholesterol

A

Lipid that regulates fluidity of the membrane

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11
Q

Factors affecting membrane structure

A

Temp -phospholipids more kinetic energy and move losing structure increase permeability and denature transport proteins
Solvents - some dissolve membranes due to them being less polar than water

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12
Q

Diffusion

A

Movement of particles from high conc to low conc
Passive processs
Until reach equilibrium

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13
Q

Factors affecting diffusion

A

Temp- higher the higher kinetic energy particles move at higher speeds
Conc differences - greater the difference the faster the rate
Down conc gradient

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14
Q

Fascilitated diffusion

A

Diffusion across a membrane through protein channels
Selective permeability - specific to one molecule or ion
Can involve carrier proteins change shape when specific molecule binds

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15
Q

Active transport

A

Movement of ions from a low to high conc by the use of energy and carrier proteins
Molecule bonds to protein
Atp binds to protein inside cell
Causes protein to change shape opening inside cell
Molecule released inside of cell and protein returns to shape

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16
Q

Bulk transport

A

For large molecules such as enzymes and hormones unable to travel through proteins
Endocytosis - into cells csm invaginate forming a vesicle which punches off and moves into membrane
Exocytosis - reverse of endocytosis

17
Q

Osmosis

A

Movement of water from high wp to a low wp

18
Q

Animal cell and osmosis

A

If placed in solution water moves into cell increasing hydrostatic pressure inside cell and eventually bursts - cytolysis
If placed in low cell will become flaccid

19
Q

Plant cells and osmosis

A

If placed in solution hydrostatic pressure increases however cell wall protects cell - turgor
If lower wp cell is said to become plasmolysed- contents shrink away from cell wall