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Cardiovascular and haemotology > membranes > Flashcards

membranes Flashcards

1
Q

what does amphipathic mean

A

consists of both hydrophilic and hydrophobic regions

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2
Q

what are cellular membranes formed from

A

phospholipid bilayers, polar hydrophilic head facing outwards and hydrophobic tails facing inside

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3
Q

name the 3 major membrane lipids

A

glycerophospholipids, sphingolipids, sterols

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4
Q

what are glycerophospholipids and describe their structure

A

-phosphorylated head group, glycerol, 2 hydrocarbon fatty acid chain
-amphipathic
-fatty acid can be saturated or unsaturated

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5
Q

what are sphingolipids and describe their structure

A

-phosphorylated head group, sphingosine backbone, 2 hydrocarbon fatty acid chains
-amphipathic

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6
Q

what are sterols and describe their structure

A

-cholesterol in animals
-influences membrane fluidity/rigidity
-unsaturated, double bonds in fatty acid tails provide space for sterols to sit in membrane

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7
Q

why have a selectively permeable barrier

A

maintain pH and ionic composition, regulate cell volume, generate ion gradient (muscles and nerve cells)

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8
Q

functions of channels/transporters/pores

A

allows compounds to enter/exit cell either along conc gradient (passively) or by using energy to go against conc gradient (active transport)

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9
Q

what do receptors and adhesion molecules do

A

bind extracellular molecules so other cells can sense them

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10
Q

name types of membrane proteins

A

channels, pores, transporters, receptors, adhesion molecules, enzymes

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11
Q

what molecules can pass through the membrane unaided and what cant

A

water, gases, urea can pass through bilayer unaided
-water needs facilitated transport by aqua porins, gases diffuse

ions, sugars, amino acids cannot pass through unaided
-need channels/transporters

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12
Q

what is diffusion rate influenced by

A

-concentration gradient steepness
-temperature
-surface area
-diffusion distance
-size/mass of substance

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13
Q

transport by diffusion is driven by differences on either side of the membrane, what are the differences that drive diffusion

A

chemical, electrical

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14
Q

examples of transporters

A

uni/sym/antiporters, ATP-binding cassette

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15
Q

what are gap junctions

A

channels that connect directly with neighbouring cells, allows rapid movement of ions

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16
Q

describe gated ion channels and give examples of each

A

highly specific for specific ions, open and close in response to a particular signal

ligand gated-acetyl choline
voltage gated- potential differences/depolarisation

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17
Q

what do transporters do

A

move compounds in and out of cell against their concentration gradients

-requires energy supplied by ATP hydrolysis

18
Q

what supplies energy for active transport

A

ATP hydrolysis

19
Q

what are symporters

A

cotransporters that transfer both molecules in the same direction

20
Q

what are antiporters

A

cotransporters that transfer molecules in opposite directions (one goes in membrane and one goes out)

21
Q

what does ABC transporter stand for

A

ATP binding cassette

22
Q

what do receptors do

A

detect extracellular signals called ligands like hormones

23
Q

how does secondary active transport/cotransport work

A

movement of a molecule down a conc gradient along with other ions like glucose, moves a molecule along its concentration gradient using energy indirectly to make a proton/sodium gradient

24
Q

what is pinocytosis

A

continuous process involving the uptake of extra cellular fluid via small membrane vesicles

25
Q

what are agonists and give an example

A

stimulate receptors, activate target as a ligand eg. insulin

26
Q

what are antagonists and give an example

A

inhibitors, blocks activation of target eg. beta blockers blocking adrenaline receptors

27
Q

function of transporters

A

move compounds in and out of cell against their conc gradient

28
Q

function of channels/pores

A

allow compounds to enter/leave along their conc gradient

29
Q

function of receptors

A

bind to extracellular molecules and convey signals across/into the cell

30
Q

function of adhesion molecules

A

allow cells to sense their environment, stick together to form tissues and adhere to extracellular matric

31
Q

name membrane proteins

A

transporters, channels, pores, receptors, enzymes, adhesion molecules

32
Q

what is active transport

A

transport of a molecule against its concentration gradient

33
Q

what is passive transport

A

-doesnt require input of metabolic energy
-driven by conc gradient

34
Q

what is exocytosis

A

secretion of proteins out and across the cytoplasmic membrane

35
Q

what is endocytosis

A

uptake of macromolecules from extracellular space across cytoplasmic membrane

36
Q

name the types of endocytosis

A

-receptor mediated endocytosis
-phagocytosis
-pinocytosis

37
Q

what is the process of exocytosis

A
  1. protein packaged into secretory vesicles by golgi and targeted to membrane
  2. vesicles fuse with membrane and release contents extracellularly
38
Q

what is the process of endocytosis

A

small portion of membrane envelopes molecule and pinches off to form a intracellular vesicle

-involves clathrin coated pits and vesicles

39
Q

what is clathrin

A

protein with 3 legged structure called triskelion which assembles into a basket structure

40
Q

what is phagocytosis

A

specialised from of endocytosis in macrophages and neutrophils to ingest bacteria and cell debri

41
Q

why cant bacteria do endocytosis/exocytosis and what do they do instead

A

they have dedicated transporter systems called translocases and the cell wall doesnt allow exo/endocytosis

42
Q

what are translocases

A

dedicated transporter systems in bacteria

Cardiovascular and haemotology (11 decks)

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