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Biology 241 > Topic 3 > Flashcards

Topic 3 Flashcards

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1
Q

what are lipids

A

water insoluble molecules composed mostly of carbon and hydrogen molecules (hydrocarbons)

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2
Q

what are biological lipids? (examples)

A

triglycerides (energy storage)
phospholipids (membranes)
sterols (membranes)

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3
Q

what are fatty acids?

A

a long chain of C atoms with a carboxyl group at one end
-hydrocarbons

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4
Q

how do fatty acid molecules vary?

A

the number of hydrocarbons in the chain (normally between 12 and 24)
-presence and number of carbon-carbon double bonds

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5
Q

what is the difference between an unsaturated fatty acid and a saturated fatty acid?

A

unsaturated fatty acids have one or more double bonds that create a kink in the chain (veg oil)
-saturated fatty acids only have single bonds (animals)

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6
Q

what are triglycerols?

A

energy storage molecules
-three fatty acids bound to a glycerol anchor

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7
Q

what are phospholipids?

A

a component of membranes

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8
Q

what are phospholipids composed of?

A

head group
tail

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9
Q

characteristics of phospholipid heads?

A

polar
water soluble (hydrophilic)
form noncovalent hydrogen bonds

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10
Q

characteristics of the phospholipid tail?

A

water insoluble (hydrophobic)
nonpolar
composed of hydrocarbon chains
have vanderwaals interactions

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11
Q

characteristics of the phospholipid tail?

A

water insoluble (hydrophobic)
nonpolar
composed of hydrocarbon chains
have Vanderwaals interactions

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12
Q

what are membranes?

A

selectively permeable barriers
-scaffolds for communication and chemical reactions

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13
Q

what is the fluid mosaic model?

A

lipids and proteins coexist in a membrane
-molecules (lipids and proteins) can move laterally (side to side) in the membrane

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14
Q

functions of membrane proteins?

A

transport = chanels/carriers
enzymes = proteins
signals bind to hormones
attachment to other cells

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15
Q

what is membrane fluidity?

A

the viscosity of a lipid bilayer (how easily things can flow through it)

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16
Q

what factors increase membrane fluidity?

A

shorter fatty acid tails
unsaturated fatty acids
presence of sterols
increase in temperature

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17
Q

what factors decrease membrane fluidity?

A

long fatty acid tails
saturated fatty acids
presence of sterols
decrease in temperature

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18
Q

how do sterols regulate membrane fluidity?

A

they prevent freezing by stopping phospholipids from packing too tightly
-prevent melting by filling gaps between phospholipids

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19
Q

what are sterols?

A

cholosterols (normally animal) that are inserted into bilayers

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20
Q

what does membrane fluidity affect?

A

permeability of the membrane

21
Q

what happens when membranes are leaky?

A

more solutes can pass through the bilayer more quickly

22
Q

why are viscous membranes better barriers?

A

fewer solutes can pass by the bilayer less quickly

23
Q

which molecules cannot diffuse across a lipid bilayer?

A

large charged and polar molecules, ions

24
Q

which molecules can diffuse accross a lipid bilayer?

A

small, uncharged and barely polar molecules

25
Q

why do cells need selective barriers?

A

cells are in dynamic environments where conditions are always changing
-helps maintain homeostasis by transporting only what the cell needs
-allows for different concentration inside the cell compared to the outside
-transport of molecules is regulated by the cell

26
Q

what is diffusion?

A

the tendency of dissolved molecules to evenly distribute themselves in a solution

27
Q

characteristics of diffusion?

A

molecules move from high concentration to low concentration
-equilibrium is eventually reached
-energy comes from the concentration gradient
-increase in entropy when molecules are evenly dispersed

28
Q

what happens in diffusion once equilibrium is reached?

A

the concentration gradient has been eliminated
-lower energy state

29
Q

what is osmosis?

A

the diffusion of water
-low solute concentration to high solute concentration

30
Q

what is tonicity?

A

the solute concentration difference across a lipid bilayer

31
Q

what does tonicity affect?

A

diffusion/osmosis accross a membrane

32
Q

what are the three major types of tonicity?

A

isotonic
hypotonic
hypertonic

33
Q

what is isotonic?

A

same concentration on the outside as the inside
-no movement of water, cells don’t change in shape or size

34
Q

what is hypotonic?

A

lower concentration outside the cell than inside
-water diffuses inward and the cell swells

35
Q

what is hypertonic?

A

higher concentration inside the cell than outside
-water diffuses out of the cell and the cell shrinks

36
Q

what are the two types of passive transport?

A

facilitated diffusion
simple diffusion

37
Q

what is simple diffusion?

A

small hydrophobic polar molecules diffuse directly across the membrane

38
Q

characteristics of simple diffusion?

A

moves down with the gradient
-powered by potential energy in the concentration gradient
-greater gradient= grater rate of movement

39
Q

what is facilitated diffusion?

A

large charged and polar molecules get help crossing the membrane by protiens

40
Q

characteristics of facilitated diffuesion?

A

down with gradient
-does not require ATP
-transporter is specific to molecule
-rate is gradient specific
-direction of transport is reversible
-channel for small molecules, carrier for large molecules

41
Q

why do cells need to concentrate molecules in the cell?

A

because cells live in dilute environments

42
Q

how do cells establish a concentration gradient?

A

cells move solutes away from equilibrium

43
Q

what is required in establishing a concentration gradient?

A

an energy source like atp (active transport)

44
Q

what is primary active transport?

A

highly specific protein pumps that cross the membrane to move solutes against its concentration gradient

45
Q

how does primary active transport function?

A

it uses ATP to power the transporter of the molecule
-can generate both chemical concentration gradient and electrochemical concentration gradients

46
Q

what is secondary active transport?

A

specific protein pumps that cross the membrane to move solutes against its concentration gradient

47
Q

how does secondary active transport function?

A

powered by energy released as a different solute moves down its concentration gradient
-uses symporters and antiporters

48
Q

what are symporters?

A

both solutes move in the same direction

49
Q

what are intiporters?

A

solutes move in opposite directions

Biology 241 (12 decks)

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