Biological Membranes

Front 1

plasma memnranes

Back 1

are partially permeable membranes

Front 2

what is a phospholipid made of?

Back 2

-hydrophillic head
-hydrophobic tail

Front 3

what is the hydrophillic part of the phospholipid?

Back 3

-the head
-polar

Front 4

what is the hydrophobic part of the phospholipid?

Back 4

-the tail
-non-polar

Front 5

what do muscle cell membranes do/have?

Back 5

-contain a large number of channels
-allows rapid uptake of glucose, providing energy for muscle contracting

Front 6

what do the membranes of shoot cells do/have?

Back 6

-have receptors allowing them to detect molecules that regulate growth

Front 7

what do the membranes of white blood cells have/do?

Back 7

-have proteins allowing recognition of foreign cells or/and bodies

Front 8

what is meant by partially permeable membranes?

Back 8

membranes that are permeable to some solutes and water

Front 9

describe extrinsic proteins

Back 9

-on the surface of the membrane or only partly embedded in it
-give mechanical support
-also work in conjunction with glycoproteins

Front 10

describe intrinsic proteins

Back 10

-span the width of the phopholipid bilayer
-some are enzymes
-others help to transport water-soluble material acrossmembrane

Front 11

describe channel proteins

Back 11

-faciliated diffusion
-small water-soluble molecules and ions such as calcium
-specialised to a specific molecule or ion
-gated so can be opened or closed
-charged or hydrophillic (water loving) molecules and ions allowed through
-NO ATP required

Front 12

describe carrier proteins

Back 12

-faciliated diffusion
-"flip-flop" carrier can take molecule in either direction depending on the concentration gradient
-chareged or hydrophillic molecules and ions allowed through
-specialsed to specific molecule
-when specific molecule fits it will change shape and allow molecule to move through
-NO ATP required

Front 13

describe simple diffusion

Back 13

-oxygen and carbon dioxide pass through the phospholipid bilayer
-travels down a concentration gradient
-lipid-based molecules also pass through such as steroid hormones
-NO ATP required

Front 14

what are diffusion, osmosis and faciliated diffusion known as?

Back 14

passive processes

Front 15

what are known as active processes?

Back 15

-active transport
-endocytosis
-exocytosis

Front 16

whats the differences betwenn active and passive processes?

Back 16

active needs ATP energy whereas passive doesnt

Front 17

describe cholesterol

Back 17

-ANIMAL cells only
-hydrophobic (water hating)
-add strngth to membrane
-prevents leaking of dissolved ions and water
-pulls fatty acid tails (hydrophobic) together
-hence limiting movement but not causing them to become rigid

Front 18

what is a glycoprotein?

Back 18

-a recognition site for hormones and neutrotransmitters
-made of carbohydrates and extrinsic proteins

Front 19

glycocalyx

Back 19

glycolipids and glycoproteins

Front 20

what is a glycolipid?

Back 20

-a recognition site for specific chemicals
-made of carbohydrates and phospholipids

Front 21

what are the differences between gluycolipids and glycoproteins?

Back 21

+glycolipids
-for specific chemicals
-sits on phospholipids

+glycoprotein
-for hormones and neutrotransmitters
-sits on an extrinsic protein

Front 22

what is a solvent?

Back 22

a liquid

Front 23

what is a solute?

Back 23

a dissolving ion, salt or sugar

Front 24

what does clostridium do?

Back 24

-causes paralysis and is found in dirt and soil
-often used in cosmetic surgery

Front 25

what do beta-blockers do and how?

Back 25

-stop the heart reacting to adrenalin
-specific shape so only block adrenalin
-some processes mimick the body

Front 26

describe how HIV works

Back 26

-HIV virus enters cell
-HIVs genetic material copies onto the nucleus of the cells DNA
-HIV virus now in the body and cant be disposed of as encoded onto the DNA of the cells. destroy DNA, destroy yourself

Front 27

why are receptors important?

Back 27

-must sense whats presentin the environment
-single-celled organisms must be able to move towards and detect what is present around them
-in multi-cellular organisms each cell must do its job for coordination to be successful.
-receptors help to carry out growth, development, movement and excretion

Front 28

describe hormone receptors

Back 28

-chemical messengers made by special chemicals that are released into organism
-communication is mediated by hormones
-bind to target membranes as they have complimentary shapes
-binding of a receptor and hormone causes target t o respond in a certaqin way

Front 29

what is a target membrane?

Back 29

cells with receptors for hormones

Front 30

describe insulin receptors

Back 30

-a type of hormone receptor
-insulin released from the pancreas in response to blood sugar levels
-attaches to insulin receptors on the plasma membranes
-triggers internal response making more glucose channels present on the surface membrane
-allows more uptake of glucose hence reducing the glucose level

Front 31

what is insulin?

Back 31

a protein

Front 32

describe medicinal drugs

Back 32

-interefere with receptors
-complementary to shape or type of receptor
-some block receptors
schizophrenia drugs mimick natural neutrotransmitters

Front 33

describe hijacking receptors

Back 33

-viruses bind to the receptors on plasma membranes that normally bind to host signalling molecules
-HIV enters the cells of the immune system. it will reproduce and eventually destroy
-poisons also bind with receptors on the muscle fibres

Front 34

if molecules are not requiring ATP energy to move where do they get there energy?

Back 34

kinetic energy

Front 35

what happens when molecules are distributed evenly?

Back 35

there is no net movement. they have reached a state of equilibrium

Front 36

why and where in the body is the state of equilibrium never reached?

Back 36

-in the lungs
-to maintain a steep concentration gradient, meaning that there is a constant change of oxygen and carbon dioxide in and out of the boidy via the lungs

Front 37

what speeds up the rate of diffusion?

Back 37

+temperature
-cells have increased kinetic energy

+concentration gradient
-the higher the concentration on one side means the quicker the diffusion

+stirring/movement
-increases the movement of molecules and hence diffusion

+surface area to volume ratio
-the bigger s.a to volume ratio the quicker things will diffuse
-things have a wider/bigger surface to diffuse across so will be quicker

+distance
the thicker the membrane the slower the rate of diffusion because further to travel

+size of molecules
-smaller the m olecules the quicker they will diffuse

Front 38

how do lipid based molecules pass through the phospholipid bilayer?

Back 38

-simply diffuse through the bilayer as they are lipid based which is the same as the fat soluble molecules of the phospholidid tail.
e.g steriod hormones

Front 39

how do small molecules and ions pass through the phospholipid bilayer?

Back 39

-carbon dioxide and oxygen are small enough to fit inbetween the phosholipids
-some water molecules even pass through even though they are polar

Front 40

what travels by faciliated diffusion?

Back 40

larger or charged molecules

Front 41

give an example of molecules moved by simple diffusion and channel and carrier proteins

Back 41

+simple diffusion
-carbon dioxide
-oxygen

+carrier proteins
-glucose
-amino acids

+channel proteins
-sodium ions
-calcium ions

Front 42

how is osmotic potential determined?

Back 42

the number of free water molecules (that are not attracted to anything else)

Front 43

in an animal cell what is meant by heamolysis?

Back 43

an animal cell that has burst

Front 44

what is meant by a crenated animal cell

Back 44

a shrunken animal cell

Front 45

what way does water move?

Back 45

water moves by osmosis from an area of high water (LESS NEGATIVE) potential to an area of low water (MORE NEGATIVE) potential

water will move from the kPA closer to 0 to the more negative kPa

for example -34 will move to -567. it tries to dilute the bigger negative

Front 46

what does active trsnsport refer to?

Back 46

the movement of ions or molecules that are pumped across the membrane by protein pumps that use ATP energy

Front 47

describe active transport

Back 47

-molecule can only move to one side. not reversible
-shaped to fit specific molecule
-shape of pump chnges by ATP energy, moving ot to the other side
-shape change means that the molecule cant go back the wrong way.

Front 48

describe the calcium ion movement in the muscles

Back 48

-muscles only contract if calcium ions are present
-when muscles are stimmulated to contract calcium ions are released from endoplasmic reticulum
-whem muscles relax the calcium ions are pumped into stores by calcium pumps on the ER

Front 49

how do cells move things in bulk transport?

Back 49

endocytosis-in
exocytosis-out

Front 50

how does endocytosis and exocytosis work?

Back 50

-uses ATP energy
-pinches off molecule and forms it into a vescles (endocytosis)
-vesciles hold things being moved around
-then excretes molecule/s (exocytosis)

Front 51

give some exmples of endo and exo cytosis

Back 51

+hormones
-pancreatic cells make insulin in large quantities
-its processes and packaged into vesciles
-membranes fuse with the vesciles to release insulin into the blood

Front 52

how do phagocytes use endo and exocyrosis to their advantage?

Back 52

-phagocytes (white blood cells) engulf invading micro-organisms
-they form them into vesciles and fuse the vescile with lysosomes so the enzymes digest the mirco-organism

Front 53

what does ENDO mean?

Back 53

inwards

Front 54

what does EXO mean?

Back 54

outwards

Front 55

what does PHAGO mean?

Back 55

solid

Front 56

what does PINO mean?

Back 56

liquid

Front 57

what does isotonic mean?

Back 57

-the external and internal water potential of the cell are the same
-there is no net movement

Front 58

what does hypotonic mean?

Back 58

-less negative water potential outside the cell than there is inside the cell
-hypo=less
-hypotonic=less negative, closer to 0

Front 59

what does hypertonic mean?

Back 59

-more negative water potential outside the cell
-hyper=more
-hypertonic=more negative, further away then 0. bigger negative

Front 60

athletes often have energy drinls after racing. they are designe to put the energy back into you, so what is the tonicity (name) of these drinks?

Back 60

hypotonic
-have more sugar n stuff inside so a bigger nagative as not pure water

Front 61

describe the problem with insects and animals that live in frshwater

Back 61

-freshwater is pure, hypotonic 0kPa so water will flow into the animal because cells are never 0kPa as they have salts and sugars in, which are hypertonic.
-this water constantly has to be pumped out.

Front 62

what happens if a cell is places in a hypertonic solution

Back 62

-more negative in the water so cell will lose water as it trys to dilute it.

Front 63

what will happen if you out a cell into a hypotonic solution?

Back 63

-solution is closer to 0 so less negative. it will move into the cell as it trys to dilute it

Front 64

why do the phospholipids form a double layer?

Back 64

-phosphate heads are hydrophillic and love the water
-fatty acid tails hate the water and are hydrophobic
-because either end is the opposite to each other they form a double layer beacuse there are 2 sides of water

Front 65

why is the membrane impermeable to biological molecules

Back 65

-too large
-not lipid soluble
-polar

Front 66

what are the diferences between active transport and diffussion and osmosis

Back 66

+diffussion and osmosis
-move from high to low concetration/water potential
-move down a concentration/water potential gradient

+active transport
-uses pumps and carriers formed by proteins
-inhibited by metabolic poisons

Front 67

what does lysis mean?

Back 67

burst

Front 68

what cells do crenated and heamolysed relate to?

Back 68

animal cells only

Front 69

what cells do turgid and plasmolysed refer to?

Back 69

plant cells only

Front 70

what molecules can pass through the phospholipid bilayer?

Back 70

molecules that dissolve in lipids

Front 71

what molecules pass through the protein pores?

Back 71

water soluble molecules

Front 72

what do proteins do?

Back 72

act as carriers and have an important role in faciliated diffusion and active transport

Front 73

when is diffusion useful?

Back 73

its a very slow process so only when distances are very small

Front 74

does the cell membrane have control over the pace or direction of the movement of molecules

Back 74

no and neither does the organism

Front 75

what speeds up faciliated diffusion across the membrane?

Back 75

carrier proteins

Front 76

do different membranes have different carriers?

Back 76

yes

Front 77

what does active transport require?

Back 77

-carrier proteins that are very specific
-ATP energy from respiration
-enables cells to go against a concentration gradient

Front 78

how do you measure the rate of diffussion?

Back 78

surface area x diff.in concntration
---------------------------------------
thickness of exchange surface

Front 79

describe ways in whgic a cell is adapted for quick and efficient diffusion

Back 79

-large surface area
-maintain a steep concentration difference
-very thin exchange surface
-increase in temperature

Front 80

what is the saturation effect of active transport?

Back 80

-as the external concentration increases so does the rate of faciliated diffussion and active transport
-they are then transporting molecules at their fastest known as the maximum turnover rate
-if the external concentration was to increase this wouldnt speed up the rate of movement