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CELS191 > Plasma Membrane and Organelles > Flashcards

Plasma Membrane and Organelles Flashcards

1
Q

What must a cell do?

A
  • Manufacture cellular materials
    -Obtain raw materials
    -Remove waste
    -Generate the required energy
    -Control the conditions inside the cell
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2
Q

What is the plasma membrane and its function?

A

The plasma membrane is the perimeter or boundary of the cell. It provides particular conditions inside the cell, which may be different depending on the cell type. It acts as a semi-permeable barrier to allow things to move across.

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2
Q

The smaller the cell is….

A

The smaller the cell is, the easier it is for things to move across the membrane, like nutrients which pass in and out of it. As the cell gets bigger, it would be harder for the bigger cells to get nutrients in and out.

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3
Q

Functions of the plasma membrane

A
  • Allows the passage of oxygen, nutrients and waste
    -Controls movement of substances in and out of the cell
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4
Q

Why is there a limit to the cell size/ maximum cell size?

A

There is a limit to the cell size because it won’t get enough nutrients to survive if it is too big. A small cell has a greater surface to volume ratio than a larger cell.

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5
Q

Explain the structure of the phospholipid bilayer

A

The plasma membrane is made out of two layers of phospholipids. A phospholipid has a hydrophilic head, arranging itself with two layers facing out, while the hydrophobic tails face each other on the inside. Cholesterol in this bilayer help stabilise the fluidity of the membrane.

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6
Q

The plasma membrane is not…

A

static. It is constantly dynamic and moving. The phospholipids are swapping with one another, proteins are coming and leaving and fusion of bubbles are present.

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7
Q

What three things control the consistency of the phospholipid bilayer?

A

-Saturation
-Temperature
-Cholesterol

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8
Q

If the plasma membrane is saturated…

A

the tails of the phospholipids are packed tightly together, with not much space and less fluidity.

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9
Q

If the plasma membrane is unsaturated, ….

A

the tails would push each other away, preventing it from tightly packing together and there is more fluidity and space.

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10
Q

High temperature of the plasma membrane means..

A

more fluidity

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11
Q

Low temperature of the plasma membrane means …

A

more fluidity

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12
Q

To ensure that the fluidity of the membrane is just right…

A

cholesterol helps stabilise it.

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13
Q

Why are proteins important for a cell to work properly?

A

They determine the function of the cell and the plasma membrane.

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14
Q

The cell can have many different types of proteins…

A

Which can be available all the time or not, depending on what the cell needs. Some proteins can have chains sticking off them or extra proteins or are attached to things inside the cells.

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15
Q

What are the five key functions of the membrane proteins?

A

-Signal transduction
-Cell recognition
-Intercellular joining
-Linking cytoskeleton and extracellular matrix
-Membrane transport

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16
Q

Explain signal transduction

A

Membrane proteins are involved in signal transduction which is taking a signal from one form and location and putting it into another form and location. The job is to relay information from the environment or from elsewhere in the body and into the cell.

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17
Q

What happens during signal transduction

A

The membrane protein and a signalling molecule travels and finds a receptor that binds it specifically, giving it information with which it passes it on to proteins in the cell which causes different things to happen (grow, divide, move, make something or die)

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18
Q

What happens as a result of the signal transduction?

A

Cells could either grow, divide, move, make something or die.

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19
Q

What is a glycoprotein?

A

A membrane protein that has added sugars.

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20
Q

It is important that cells can recognise each other in the body.

A

For example, the immune system has to recognise if a cell is foreign/an invader. Membrane proteins can do that as well.

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21
Q

Cell Recognition often involves…

A

glycoproteins

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22
Q

What happens during cell recognition?

A

Another cell will have a membrane protein that will perfectly match up with the sugars and/or shape of the glycoprotein when they come in contact with each other, they recognise one another as a cell.

23
Q

Some cells in the body float around on their own but..

A

others work collectively together as clumps or sheets of cells like skin. They have to be anchored together. This is called intercellular joining.

24
Q

The process of intercellular joinng involves

A

One cell attaching strongly to a membrane protein from another cell. Then they are anchored together and held in place.

25
Q

How long does intercellular joining last?

A

Some proteins form long lasting connections between cells while some are only for short periods of time.

26
Q

Membrane Transport

A

allows small amounts of molecules to move across the membrane and can be passive or active.

27
Q

Linking cytoskeleton and extracellular matrix allows..

A

Allows a cell to physically connect with protein structures outside the cell/ the extracellular matrix.

28
Q

What is the extracellular matrix

A

Anything outside the cell like fibres, sugars and proteins, often made by the cell itself.

29
Q

With membrane transport, what membrane proteins are utilised?

A

Membrane proteins that either have a channel or a carrier which allows to move small amounts of particular molecules to move across the membrane.

30
Q

What are the factors for substances to move across membranes?

A
  • What the molecules are
  • How big the substances are
    -How much is moving at once
  • If it is through bulk transport or through membrane transport
30
Q

Differences between passive and active transport

A

Molecules move DOWN the concentration gradient and no energy is needed in passive transport. Molecules move AGAINST the concentration gradient and energy is needed.

31
Q

What types of movement do not require any energy

A

Diffusion and Facilitated Diffusion

32
Q

What types of movement require energy

A

Active transport and co transport

33
Q

Diffusion

A

Hydrophobic molecules such as steroid hormones and gasses move down from a high concentration gradient to a low concentration.

33
Q

If a molecules wants to move across the membrane and is lipid soluble, and the membrane is made out of phospholipids,

A

it does not need help to move across and can just make its way across the plasma membrane.

34
Q

If there are water molecules or molecules that have a charge to them,

A

the plasma membrane is going to reject them and won’t let them get through in diffusion.

35
Q

Facilitated Diffusion

A

The movement of hydrophilic molecules requiring membrane proteins called channels and carriers, which aid the movement of specific substances down their concentration gradient. No energy is required, but some channels open and close in response to signals.

36
Q

Carriers undergo a…

A

shape change to help guide the molecules.

37
Q

Protein membrane: Channel

A

A protein is hollow in the middle and as long as there are fewer molecules inside the cell than outside the cell, they can move through the channel inside for free.

38
Q

Protein Membrane: Carrier

A

Carrier proteins change shape in the presence of what they are trying to move. This protein changes shape and opens up to allow/guide molecules to move down the gradient from one side to another. It can also move in the opposite direction as well.

39
Q

Why do cells osmo regulate?

A

To prevent swelling or shrinking under conditions that might affect it

40
Q

The water will only move easily if…

A

there are membrane proteins in the plasma membrane called aquaporins

41
Q

Definition of aquporins

A

Water channel

42
Q

What happens during facilitated diffusion, using aquaporins in your answer

A

Water will move from a high water concentration moving down the aquaporin to the low water concentration.

43
Q

If there is a high water concentration,

A

there is a low solute concentration

44
Q

If there is a low water concentration,

A

there is a high solute concentration

45
Q

To move things against the concentration gradient,

A

the process of active transport is done with the help of ATP.

45
Q

Transport proteins will only let molecules move it…

A

ATP (Adenosine Triphosphate) is present.

46
Q

To take molecules inside the cell,

A

energy is needed to push them in. Carriers will let the molecules in and with only the presence of ATP will it change shape to let the molecules inside the cell against the concentration gradient.

47
Q

Active transport is where molecules move…

A

AGAINST the concentration of a low to a high concentration gradient, with the help of ATP.

48
Q

Active transport allows a cell to have…

A

an internal concentration of a substance that is different from its surroundings

49
Q

What happens during co-transport

A

It is when one substance that is being actively pumped across the membrane with energy and its concentration gradient created by pumping the substance is used to generate the movement of a completely different substance against its concentration gradient.

50
Q

Functions of organelles

A

-Provide special conditions for specific processes
-Keep incompatible processes apart
-Allow specific substances to be concentrated
-Form concentration gradients
-Package substances fro transport or export

51
Q

Explain the structure of the plasma membrane

A

The two layers of the phospholipid bilayer is composed of the heads facing outwards while the tails are facing inwards forming a semipermeable layer. Cholesterol in the layer is helping to stabilise the fluidity.

51
Q

Some of the processes and the conditions that a cell needs are different and in conflict with the conditions needed somewhere else in the cell.

A

organelles keep them separate and apart. It allows things to move from one place to another while keeping it protected and in its environment while still moving it around the cell.

52
Q

What are the barrier surrounding the organelles made out of

A

The same materials that make the plasma membrane

CELS191 (9 decks)

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