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Physiology > Exam 2: January 23-27 > Flashcards

Exam 2: January 23-27 Flashcards

1
Q

what are the functions of the plasma membrane?

A

1) it’s the boundary around our cell that acts as a discriminating barrier
2) it binds chemical messengers through the proteins on the surface of the cell
3) it sets cell characteristics such as shape and motility

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2
Q

how does the plasma membrane set cell characteristics?

A

it can set the shape and motility

cells can move themselves sometimes instead of being immobile

it can also be a connection to other cells which is needed to make tissues which turn into organs

also connects cells with the EC matrix

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3
Q

what are the components of the plasma membrane?

A

1) phospholipids
2) cholesterol
3) proteins
4) glycocalyx

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4
Q

what form does the plasma membrane have?

A

it’s a fluid mosaic model

you expect it to be constantly moving and made of lots of components

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5
Q

what are phospholipids?

A

part of the plasma membrane - the main building block of the PM

it has a polar head with 2 non polar tails = amphipathic

polar heads like being associated with intercellular fluid while tails don’t so they group together and bond due to hydrophobic bonding and a bilayer forms spontaneously

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6
Q

what is cholesterol?

A

part of the plasma membrane

1:1 relationship with the phospholipids

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7
Q

how does cholesterol prevent certain molecules from getting through the PM?

A

small polar molecules can’t go through the membrane as easily

Na+ get’s bounced easily by the hydrophobic tails because it’s charged however, water isn’t charged but it’s polar and it can slip through the gaps in the membrane but cholesterol fills those gaps

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8
Q

what function does cholesterol serve?

A

increases stiffness of the PM

allows for controlled bending of phosphomembrane and without cholesterol you couldn’t make a sphere shape

also helpful for vesicle formation!

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9
Q

what is a protein?

A

1:50 ratio with phospholipids but they’re actually half the mass of the plasma membrane aka they’re really big

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10
Q

what are the two types of proteins?

A

1) integral

2) peripheral

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11
Q

what are integral proteins?

A

ALWAYS amphipathic because part of it is in the phospholipid membrane and the other is associated with the interstitial/intercellular fluid

most are transmembrane proteins but not always

cannot be removed from the membrane without destroying the PM

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12
Q

what are the types of integral proteins?

A

1) channels

2) receptors

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13
Q

what are channels?

A

a type of protein which allow polar compounds to cross the membrane without having to associate with the non polar region

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14
Q

what are receptors?

A

a type of protein that is on the surface of the cell and receives signals and can also be anchors

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15
Q

what are peripheral proteins?

A

predominantly on the intracellular cellular fluid side aka the inside of the cell

can impact the shape and motility of the cell

proteins on the outside are extracellular matrix proteins

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16
Q

what is the glycocalyx?

A

the branch sugar structures that we find on the extracellular fluid side of our membrane - we don’t see it on the inside

it can be attached to phospholipids and integral proteins

causes a fuzzy appearance – glycocalyx is 3D and you can only focus on one plane at a time so it’s easy to focus in inside of PM but not the outside with a microscope

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17
Q

what are the functions of the glycocalyx?

A

1) identification
2) mechnical protection
3) limits cell growth

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18
Q

how does the glycocalyx serve as identification?

A

the glycocalyx on Bronson’s cells are different than mine

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19
Q

how does the glycocalyx serve as mechanical protection?

A

glycocalyx kind of stick out and look like hairs on our arm and they help us to prevent things from getting to our skin so the glycocalyx gives us mechanical protection for our cells so things can’t get to integral proteins or our phospholipids

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20
Q

how does the glycocalyx limit cell growth?

A

it limits how close cells can be to each other so it limits cell growth

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21
Q

what are junctions?

A

direct linkage of cells

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22
Q

what are the types of junctions?

A

1) gap junctions
2) desmosomes
3) tight junctions

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23
Q

what are gap junctions?

A

they are direct linkages that are small channels created by proteins called connexons

it’s multiple connexons that help make the gap junction

not that strong

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24
Q

what are gap junctions made by?

A

proteins called connexons

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25
Q

is there ICF or ECF flow with gap junctions?

A

ICF flow? Yes! Things can move from cell to cell without leaving either cell - whomever this is also limited because you can’t move huge things through them, only small things

ECF flow? Yes! water can just go around the gap junctions and get around them like it it’s raining and you’re standing under a walkway you’ll still get wet because water can go around the tunnels

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26
Q

what are desmosomes? what are they made up of?

A

made up by cadherin protein linkages where cadherin linkages are proteins that both cells have

it’s the strongest connection

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27
Q

is there ICF or ECF flow with desmosomes?

A

ICF flow? No! there’s not peace for anything to move because it’s just proteins linking up and forming a bond

ECF flow? Yes! because just like gap junctions you can go right around it

like two people’s arms stuck together by gum

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28
Q

what are tight junctions? what are they made up of?

A

they create the sealing of our plasma membrane

they’re made of claudin protein linkages which are also proteins that come from both cells

we’re creating a zipper around the cell, not buttons - multiple cells are connecting all the way around

forces movement through the cell aka transcellular so you have more control since your membrane is selective

you want this in epithelial cells because they’re supposed to be a barrier and you don’t want things to be slipping through them

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29
Q

is there ICF or ECF flow with tight junctions?

A

ICF flow? No!

ECF flow? No!

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30
Q

why is ATP an energy source for cellular metabolic pathways?

A

Phosphates are high energy bonds because it’s a covalent bond which is very strong and breaking it releases a lot of energy

aka equation 1: ATP ADP + Pi + energy

you don’t invest ATP, you have to make it

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31
Q

what are the two ways to make ATP?

A

1) substrate level phosphorylation

2) oxidative phosphorylation

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32
Q

what is substrate level phosphorylation? where does it happen?

A

bound Pi transferred to ADP to create ATP

ADP + XP ←→ ATP + X

happens in glycolysis and TCA cycle

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33
Q

what is oxidative phosphorylation? what’s an example of it?

A

you create an energy input that allows us to transfer an unbound Pi to ADP

equation 1

happens in the electron transport chain

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34
Q

what is glycolysis?

A

breaking down of sugar = catabolism of sugar/carbohydrate

a series of 10 enzymatic reactions

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35
Q

where does glycolysis occur?

A

it doesn’t require a special compartment to occur it just occurs in the cytosol

36
Q

what is the net production of glycolysis?

A

1 glucose gets us 2 ATP plus other products based on the conditions we run glycolysis under

37
Q

what are the products of glycolysis if under aerobic conditions?

A

NADH and pyruvate

aerobic means there’s oxygen

38
Q

what does NADH do?

A

it’s an intermediary that will help us move energy from one place to another

39
Q

what are the products of glycolysis if under anaerobic conditions?

A

lactate and NAD+ are made from pyruvate and NADH

40
Q

what happens if you’re under anaerobic conditions?

A

you get lactic acid build up when you’re under anaerobic conditions because you convert pyruvate to lactate so that you can convert pyruvate to lactate and NADH gets converted to NAD+ which is the “empty” dump truck

41
Q

what is the oxygen dependence of oxygen?

A

glycolysis is independent of O2 because without oxygen we can still complete the process - it just changes the end point and we get lactate and NAD+ instead of NADH and pyruvate

42
Q

how is glycolysis regulated?

A

the job of glycolysis is to make ATP so you don’t need to be running this process all the time

high [ATP] lessens glycolysis

high [ADP] increases glycolysis

43
Q

what kind of phosphorylation is glycolysis?

A

substrate level phosphorylation

44
Q

what are alternate names of the krebs cycle?

A

citric acid cycle or the tricarboxylic acid cycle or TCA cycle

45
Q

what’s the relationship between the Krebs cycle and glycolysis?

A

the Krebs cycle starts with the catabolism of pyruvate aka glycolysis feeds into the Krebs cycle

46
Q

what happens to the Krebs cycle if pyruvate isn’t available?

A

derivatives from amino acids and lipids

if we didn’t have enough glucose we could use the breakdown products from proteins (AA) and lipids (fats) to create ATP

47
Q

where does the Krebs cycle occur?

A

mitochondria

8 enzymatic reactions

48
Q

what is the net production of the Krebs cycle? what kind of phosphorylation is used?

A

2 ATP via substrate level phosphorylation plus CO2, NADH, and FADH2

49
Q

what critical equation does the Krebs cycle rely on?

A

critical equation 3 because the Krebs cycle makes CO2 which then has to be dealt with

50
Q

what is the independence on oxygen of the Krebs cycle?

A

the Krebs cycle is indirectly dependent on O2 because the krebs cycle will not work under anaerobic conditions

the reason it’s indirect is because there isn’t actually oxygen in the process - some other process that influences this one is what needs oxygen

51
Q

how is the Krebs cycle regulated?

A

high [ATP] means less Krebs cycle

higher [ADP] means more Krebs cycle

52
Q

how much ATP is made between Krebs and glycolysis?

A

4 ATP

2 from glycolysis and 2 from Krebs

53
Q

what does the ETC do? where does it happen?

A

it recycles NADH and FADH2 to make NAD+ and FAD

takes the loaded dump truck and off loads them - what’s in the dump truck is electrons - it’s moving electrons through the proteins in our mitochondria

this occurs in the mitochondria

54
Q

what’s the net production of the ETC?

A

28-34 ATP and H2O

dependent on other activities occurring in the mitichondria at the time

recycling the dump trucks gets you back NADHback so you can continue to run in aerobic conditions

55
Q

what is the dependence on oxygen of the ETC?

A

directly dependent on O2

the ETC DOES NOT HAPPEN without oxygen because there’s oxygen directly in these steps

56
Q

what happens to the water product of the ETC when you’re sick?

A

most of the time we’re making water but sometimes your immune system tweaks the process and you can instead make free radicals – this is why you need to stay hydrated when your sick because you’re making less water

57
Q

what’s the summary of glycolysis, krebs and ETC?

A

glycolysis: glucose and other molecules fuel the process to make pyruvate which makes 2 ATP

Krebs: prtuvate from glycolysis makes acetyl CoA which goes through TCA cycle to make 2 ATP

ETC: electrons carrier by NADH and FADH2 through oxidative phosphorylation

58
Q

what do tight junctions force us to do?

A

they prevent extracellular fluid movement which forces us to have to go across the plasma membrane barrier = transcellular movement

59
Q

what is a discriminant barrier?

A

it’s not an absolute barrier

60
Q

what is the purpose of the tails in the plasma membrane?

A

the non polar tails of the phospholipids in the PM limits polar movement across membrane because tails are non polar and are held together by hydrophobic interactions

61
Q

what passes through the PM easily?

A

the PM is not a barrier to small non polar compounds

NP come out on the other side because there isn’t space for them to stay in the middle with eh tails

62
Q

what has difficulty passing through the PM?

A

the PM is a barrier to any sized polar molecules and large non polar molecules

cholesterol makes it even harder for small polar molecules that could have possibly slipped through because cholesterol fills the gaps between the tails

large non-polar molecules have trouble moving across because it would disrupt the tail pattern and cause problems

63
Q

what is used to get things across the PM?

A

proteins!

channels: create a gap like a regular door

transporters/carriers: revolving door

64
Q

is everything always in constant motion?

A

Yes!

unless we’re at absolute zero (0K) components are always in random motion

65
Q

what drives motion?

A

[X]

[X] = # of X/V

66
Q

when does diffusion happen?

A

when [X] different between two areas

diffusion won’t happen if a gradient isn’t present - random motion will still be happening there just won’t be net movement

67
Q

how does diffusion work?

A

you diffuse form high to low concentration areas

it will always follow the gradient! diffusion will NEVER happen against its gradient so the cell doesn’t have to put in any energy since the compounds are all moving naturally

68
Q

what does diffusion depend on?

A

1) permeability
2) surface area
3) size of [X] gradient
4) distance

69
Q

how does diffusion depend on permeability?

A

there’s a direct relationship between diffusion rate and permeability

the higher the permeability the faster the rate

a window with a screen with different gap sizes

70
Q

how does diffusion depend on surface are?

A

direct relationship

how much space do we have for this diffusion to happen across?

the smaller the surface area the slower the diffusion rate

like a slightly open window vs. a wide open window

71
Q

how does diffusion depend on the size of the gradient?

A

direct relationship

the bigger the gradient the bigger the diffusion rate

the bigger the hill the faster you’ll be able to go down it

72
Q

how does diffusion depend on distance?

A

inverse relationship

if you take the two areas and start moving them apart it’ll take longer for diffusion to happen

diffusion has a problem with distance

our lungs and GI track are as thin as possible to make the distance as small as possible – so when distance gets larger, diffusion gets slower which is an inverse relationship

73
Q

what are examples of things that can move across the PM?

A

the bilayer is small and non polar so the only things that can diffuse across are small non polar things like O2 and CO2

74
Q

is the plasma membrane a barrier?

A

no! because things just diffuse from high to low - it’s like a chain link fence to hold in a mouse

this causes a storage problem!! we do better in making ATP if our cells are oxygenated and we aren’t in anaerobic conditions

but if we store oxygen in the cells then there isn’t enough in the interstitial fluid and the oxygen would flow out of the cell with its gradient

75
Q

what can we do to make sure the cell is getting as much oxygen as possible?

A

1) If we want oxygen always going into our cell, we want loads of oxygen outside of our cells so that the gradient is constantly sending oxygen inside our cells
2) another way to keep oxygen in our cells is to bind the oxygen to something that is too big and can’t go across the membrane (like a cone on a pet) – for example we can store oxygen in our skeletal muscles by binding oxygen to myoglobin so we don’t have to go anaerobic and have acid lactic build up

76
Q

what are channels?

A

they are solute specific!

sodium and potassium specific channels that other ions can’t move through

channels are diffusion so it’s also with the gradient and has no energy cost

77
Q

what are the types of channels?

A

1) leak channels
2) gated channels
3) aquaporins

78
Q

what are leak channels?

A

allows things to continually leak and they’re always open

relatively rare category (look like a hotdog bun)

79
Q

what are gated channels?

A

only open when triggered – they can be either open or closed - there’s multiple ways that you can set up for how that gate can be open or closed

80
Q

what are the types of gated channels?

A

1) chemically gated
2) voltage gated
3) mechanically gated
4) thermally gated

81
Q

what are chemically gated channels?

A

binding ligand – when we bind something to a protein we change its shape that gets us from being closed to open

82
Q

what are voltage gated channels?

A

electrical distribution change which changes the shape from being closed to open

83
Q

what are mechanically gated channels?

A

stretch/deform the protein from closed to open form

this can happen in association with the membrane because it’s fluid mosaic model

84
Q

what is a thermally gated channel?

A

heat/cool the protein and converts it from being closed to open

at the right temperature we have the right matching component

85
Q

what is an aquaporin?

A

water doesn’t diffuse, it does osmosis

86
Q

what is osmosis?

A

the net diffusion of H2O across a membrane

water will move from high to low water concentration

water goes from low solute concentration to high solute concentration

Physiology (15 decks)

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