2B-Cell Membranes Flashcards

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1
Q

Cell membranes

A
  • partially permeable and control which substances enter or leave the cell
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2
Q

Fluid mosaic model

A

Phospholipids form a double bilayer, channel proteins, carrier proteins , glycolipids and glycoproteins, receptor proteins on cell surface membrane and cholesterol

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3
Q

Phospholipids in cell membranes

A

Hydrophobic fatty acid tails face in so doesn’t allow large and water soluble substances (ions and polar molecules) but small non polar substances can diffuse across

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4
Q

Cholesterol

A

A lipid that gives Membrane stability and bonds to hydrophobic fatty acid tails of phospholipids causing them to pack more closely together- makes more rigid -has hydrophobic regions barrier to polar substances and maintains cell shape

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5
Q

Why blood cells have cholesterol

A

Membranes stability as free floating so maintains shape

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6
Q

Temperature below zero affect on membranes

A
  • phospholipids little energy so don’t move much. -close together so membrane rigid. -channel proteins and carrier denature increasing membranes permeability -ice crystals pierce membrane - permeability increases
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7
Q

Temp of zero to 45

A
  • phospholipids more mobile not tightly packed - partially permeable As temp increases phospholipids move more increasing permeability
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8
Q

Temp of 45 above affect on membranes

A

Bilayer melts - increasing permeability - water inside cell expands puts pressure on membrane -proteins denature increasing permeability

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9
Q

Simple diffusion

A

Passive process net movement of particles from an area of high conc to low conc across a partially permeable membrane down a conc gradient until equilibrium is established

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10
Q

Factors affecting diffusion rate

A

1- conc gradient size. 2-thickness of exchange surface. 3- surface area

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11
Q

Facilitated diffusion

A

Passive - net movement of particles from area of high concentration to low conc across a channel or carrier protein until equilibrium is reached

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12
Q

What uses facilitated diffusion

A

Large and charged polar particles and ions

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13
Q

Carrier proteins

A

1- Large molecule attaches to carrier protein in membrane 2- protein changes shape 3- releases molecule on opposite side f membrane

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14
Q

Channel proteins

A

Pores in membranes for charge particles to diffuse through

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15
Q

Factors affecting facilitated diffusion rate

A

1- conc gradient size. 2- number or channel or carrier proteins

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16
Q

Osmosis

A

Net movement of water from an area of high water potential to low water potential across a partially permeable membrane until equilibrium is reached a passive process

17
Q

Pure water water potential

A

Zero

18
Q

Water potential of any water is

A

Zero or negative

19
Q

Water potential

A

Potential of water molecules to diffuse out or in of a solution

20
Q

How to lower Water potential

A

Add solutes

21
Q

The more negative water potential

A

More solutes in it

22
Q

Isotonic

A

Same water potential so won’t gain or lose any water as no net movement of water

23
Q

Hypotonic

A

Solutions with Higher water potential compared to inside of the cell so water enters

24
Q

Hypertonic

A

Solution with lower water potential than inside the cell so water leaves the cell net movement out

25
Q

Factors affects the rate of osmosis

A

1- water potential gradient 2- surface area 3- membrane thickness

26
Q

Active transport

A

Active process-energy to move particles across a membrane against a concentration gradient

27
Q

Carrier proteins in active transport

A

1- molecule attaches to it. 2-carrier protein shape changes and moves molecule across the membrane against the concentration gradient using energy from ATP.

28
Q

Co transporter proteins in active transport

A

1- bond 2 molecules to it and changes co-transporter proteins shape. 2-concentration gradient of one of the molecules used move the other against its own conc gradient using energy from ATP

29
Q

Co- transport and absorption of glucose

A

1- Na actively transported out of epithelial cells in ileum into blood by Na-k pump- conc gradient as high conc of Na in lumen of ileum than inside cell. 2-Na diffuse from lumen of ileum into epithelial cell down conc gradient via Na and glucose co transporter proteins so conc of glucose in cell decreases. 3- glucose diffuses into blood down conc gradient via protein channel via facilitated diffusion.

30
Q

Factors affecting Active transport

A

1-speed of individual carrier proteins 2- number of carrier proteins 3- rate of cell respiration and availability of ATP

31
Q

Antigens

A

Proteins molecules that generate an immune response found on body cells