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Biology- IB > 1.4 membrane structure > Flashcards

1.4 membrane structure Flashcards

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1
Q

what are the different ways of transport particle move across membranes

A
  • simple diffusion
  • facilitated diffusion
  • osmosis
  • active transport
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2
Q

the membrane is ‘semipermeable’

what does semipermeable mean

A

to allow some, but not all molecules through.

- controls what goes in and out of the cell

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3
Q

what is passive transport

A

a form of transport which does not require energy as the molecules move from a high to low concentration->down the concentration gradient

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4
Q

examples of passive transport

A
  • diffusion
  • factiliated diffusion
  • osmosis
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5
Q

what is active transport

A

transport through the membrane which does require require energy as the molecule move from a low to high concentration–> moves against the concentratioon gradient

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6
Q

examples of active transport

A
  • ion pumps

- phagocytosis

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7
Q

what is a concentration gradient

A

where the concentration is different across an area

-i.e high and low concentration

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8
Q

what is the difference between passive and active transport

A
  • passive doesn’t require energy and goes from high to low concentration
  • active does require energy and goes from low to high concentration
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9
Q

Diffusion is a form of what type of transport

A

passive transport

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10
Q

what is diffusion

A

passive movement of particles

  • down the concentration gradient
  • higher to lower concentration
  • requires no energy
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11
Q

how does diffusion occur

A

occurs as the consequence of random motion of particles

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12
Q

why can’t all substances diffuse

A
  • the mebrane is semi-permeable so many substances can’t diffuse due to size or polarity
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13
Q

steep gradient

A

large difference in concentration between the two areas

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14
Q

what affects the speed of diffusion

A
  • the steepness of the concentration gradient
    - steeper concentration gradient= faster diffusion
  • size of the molecules
  • temperature
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15
Q

examples of substances that move via diffusion

A

mostly gases
- oxygen
carbon dioxide
-glucose

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16
Q

facilitated diffusion

A

passive transport of molecules or ions across a cell membrane

  • done through transmembrane integral proteins which transport the molecules
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17
Q

polar molecules

A
  • cannot freely diffuse due to the hydrophobic nature of the fatty acid tails of the phospholipids
  • are transported by proteins in the form of transmembrane
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18
Q

examples of factilated diffusion

A 
- glucose
sodium ions
- chloride ions
- amino acids
- nucleosides
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19
Q

ion channels

A

facilitated diffusion that involves channel proteins

- opens a channel to allow smaller molecules instead of binding to molecules

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20
Q

examples of molecules that ion channels allow through

A
  • sodium
  • potassium
  • calcium
  • chlorine
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21
Q

why do some molecules use factilated diffusion

A

the lipid bilayer is impermeable to them

e.g. the glucose molecule is to large to pass through unassisted

22
Q

what is osmosis

A

the movement of water molecules from an area of higher water concentration to an area of lower concentration through a semi-permeable membrane.

osmosis is a form of passive transport

does not require energy

23
Q

through osmosis, will water move to the hypertonic or hypotonic area and through what type of transport

A

the hypertonic area ( the low water area)

through osmosis

24
Q

what is osmolarity

A

the measure of a solutes concentration

25
Q

what osmolarity does water have

A

zero

26
Q

turgid

A

when a cell is placed in a low salt/ high water solution, the cell gains water as it is hypertonic and swells- becoming turgid.

27
Q

turgid in a plant cell vs animal cell

A

plant cell: optimal condition- turgid
- will be contained by the cell wall

animal cell/protist:
no cell wall so therefore may burst, killing the cell -lysed

28
Q

isotonic

A

when the solution and cell have the same concentration

if the cell and the solution have the same concentration then it is isotonic and they remain unchanged

isotonic saline solutions are used in medical procedures such as transporting kidneys.
- they mast be in a solution with the same osmorlatiy as a a human cytoplasm to prevent osmosis

29
Q

in fresh what cells tend to gain/lose water via what transport and why

A

gain

through osmosis

the cytoplasm contains dissolved substances and is therefore hypertonic to the fresh water which is hyoptonic

30
Q

potassium ion channels

A

they are the most common type of ion channel and are found in most cell types.
they form potassium selective pores that spend the cell membrane.

potassium ion channels are used to move K+ ions across the membrane

the channels work with the sodium-potassium pump in the axons of neurons

31
Q

the axons of neurons

A

transmit electrical impulses by translocating ions to create a voltage difference across the membrane

when at rest, the sodium-potassium pump expels sodium ions from the nerve cell, while potassium ions gather within the cell

when the neuron fires, these ions swap locations via facilitated diffusion through the sodium and potassium channels

32
Q

what type of transport is used when the neuron fires

A

facilitated diffusion via the sodium and potassium channels

33
Q

active transport

A

the movement of particles from an area of low concentration to and area of high concentration,going against the concentration gradient and requiring energy(ATP).

examples include:
the uptakes of glucose in the intestines of humans,
the exchange of Na and K+ ions in the nerve axons
uptake of mineral ions into root hair cells of plants.

34
Q

what are the two main types of active transport

A

protein pumps

  • only transport specific substances and in a specific direction,
  • substance binds to the protein
  • and energy(ATP) Is used to move the substance along

use of vesicles

  • the fluidity of the membrane allows materials to be taken into cells by endocytosis or released exocytosis
  • vesicles move materials within the cells.
35
Q

sodium-potassium pumps in nerve axons

A

nerve cells conduct nerve impules via a ‘mexican wave’ of Na+ and K+ ions in and out of the nerve.

axons contain a pump protein that moves Na+ and K+ ions across the membrane.

The ions are moved in opposite directions(antiport).

one energy(ATP) molecule is enough to transport three Na+ out and two K+ ions in.

36
Q

what are nerve cells

A

axons

37
Q

there are two states the sodium-potassium pumps have

A

In one there is more ‘binding site attraction’ for K+ ions outside the membrane.
- in this state K+ moves in and Na+ moves out.

In the other state the reverse occurs
- K+ moves out and Na+ moves in

ATP energy cause the change from one state to another

38
Q

how does ATP cause the change in the sodium-potassium pump’s states

A

it helps to establish a net charge across the plasma membrane with the interior of the cell being negatively charged with respect to the exterior.

this prepares nerve and muscle cells for propagation of nerve

39
Q

what are vesicles

A

usually small vacuoles containing proteins, that bud off from the endoplasmic reticulum or the Golgi bodies and then travel to the cell membrane

40
Q

exocytosis

A

secrection

when a vesicle fuses with the cell membrane, the contents are expelled and the membrane flattens out again

e.g.
secrection in substances: hormones, contractile vacoules in paramecin

41
Q

endocytosis

A

part of the cell membrane is pulled inward, the material in engulfed and the vesicle is pinched off

phagocytosis: is engulfing solid material
pinocytosis: is engulfing fluid material

42
Q

what are the molecules that make up living things

A

C.L.P.N.M.W
Clay lions paint nails mysteriously well

carbohydrates: glucose, starch, cellulose
Lipids: fats, waxes, oils
Proteins: enzymes, hormones, collagen, muscle
Nucleaic acids: DNA
Minerals: calcium, iron, sodium
Water

43
Q

carbon in living things

A

carbon is contained in organic compounds which are found in living things.

each carbon atom can form four covalent bonds: allows a great diversity of compounds to exist

the most common type is C-C and C-H.

44
Q

covalent bonds

A

hydrogen forms one covalent bond
oxygen and sulfer form two
nitrogen form three
Carbon can form four covalent bonds

additional groups added to the C-C molecule give the organic compound it’s properties.

covalent bonds are relatively strong so molecules are stable. weaker bonds can form between molecules.

44
Q

covalent bonds

A

hydrogen forms one covalent bond
oxygen and sulfer form two
nitrogen form three
Carbon can form four covalent bonds

additional groups added to the C-C molecule give the organic compound it’s properties.

covalent bonds are relatively strong so molecules are stable. weaker bonds can form between molecules.

life is based on carbon compounds including carbohydrates

45
Q

the theory of vitalism

A

it used to be thought that living organisms were composed of organic molecules that could only be produced by a ‘vital force’- made by a living thing

this was proved false through biochemistry discoveries which explained the living process: e.g. photosynthesis and respiration, in terms of the chemical substances and chemical reactions.

  • In 1828 Fredich Wohler synthesised urea artificially using silver isocyanate and ammonium chloride.

the structure of DNA has further explained living processes including protein synthesis, inheritance and evolution.

46
Q

synthesis of urea

A

Urea was discovered in human urine during the 18th century

the theory of vitalism would have meant that it could have only been made in living organisms with a vital force.
In 1828 Fredich Wohler synthesised urea artificially using silver isocyanate and ammonium chloride which disproved the the theory of vitalism.

47
Q

chemical synthesis

A

a key aspect to organic chemistry.

today most organic compounds that make up living organisms can be synthesised.
this is often used by pharmaceutical companies to. identify compounds from plants and animals and artificially synthesise them for use

e.g. hormones, enzymes, painkillers.

48
Q

metabolism

A

metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.

reactions may be anabolic or catabolic.

a metabolic pathway is a series of chemical reaction within a cell.

49
Q

anabolism

A

the synthesis of complex molecules from simpler molecules including the formation of complex molecules including the formation of macromolecules from monomers via condensation reactions.

examples include the synthesis of sugar from CO2, (photosynthesis), the synthesis of large proteins from amino acid building blocks, and the synthesis of new DNA strands from nucleaic acid building blocks

anabolic steriods build muscle and protein

50
Q

catabolism

A

The breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers

example
respiration where glucose is broken down. into carbon dioxide and water to produce energy(ATP)

Biology- IB (10 decks)

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