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Biology 101 > Unit 5- Cell (Plasma) Membrane > Flashcards

Unit 5- Cell (Plasma) Membrane Flashcards

1
Q

What is The Fluid Mosaic Model?

A

Plasma membranes are dynamic and constantly in flux.

The fluid nature: due to fatty acids tails and cholesterol embedded in the membrane (in animal cells)

The mosaic nature: proteins and protein- carbohydrate complexes found throughout the membrane
Diversity of different macromolecules
Bilayers- two layers of phospholipids and proteins embedded in those layers
Sugars were attached to the exterior surface of the membrane
Cholesterol imparts rigidity and some resistance to flow- Important in the viscus nature of membrane

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2
Q

Who came up with the fluid mosaic model?

A

Nickelson and Singer-1972

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3
Q

What is the structure of Phospholipids in the plasma membrane/

A

Phospholipids form a 2-layer cells membrane that separates fluid within the cell from the fluid outside the cell

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4
Q

the plasma membrane has phospholipids structure that is Amphipathic- _________ heads and ________ tails

A

hydrophilic/hydrophobic

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5
Q

The plasma membrane is________

A

Selective permeability- they allow some substances to pass through, but not others

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6
Q

The selective permeability process is called

A

Diffusion

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7
Q

Which substances can pass through the membrane?

A

lipid-soluble substances (fat soluble vitamins or hormones)- Nonpolar molecules
O2, H2O, CO2- small molecules essential to life.
They have to diffuse through quickly

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8
Q

Which substances cannot pass through the membrane?

A

Substances that cannot pass through the membrane and must pass through transport proteins channels
Ions- Na+, K+
Simple sugar and amino acids- any molecule that has polarity

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9
Q

What is Passive transport?

A

No energy ( ATP) required

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10
Q

Substance move from an area of _______ concentration to an area of ______concentration

A

higher/lower

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11
Q

What are Factors affecting the rate of diffusion:

A

Diffusion gradient- The steeper, the higher the rate
Size of molecules or ions- The smaller the size the higher the rate
Temperature- the higher the temp, the higher the rate
Diffusion medium- rate in gas> rate in liquid> rate in solide
Surface area- the larger the surface area, the higher the rate
Why cells are microscopic- allows diffusion to be faster

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12
Q

What is facilitated transport

A

A type of passive transport that does not require energy to move molecules down their concentration gradient. Uses membrane proteins to move molecules across the membrane that are large or charged (ions)

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13
Q

Examples of facilitated transport?

A

Glucose and amino acid transport- Since glucose is a large polar molecule, it cannot pass through the lipid bilayer of the membrane. Thus, it needs carriers called glucose transporters to pass through.

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14
Q

______ molecules need a channel or carrier

A

Polar- because they cannot pass through the plasma membrane

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15
Q

Name three forms of passive transport

A

1) DIffusion
2) Osmosis
3) Transport protein

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16
Q

Channels are_______

A

always open

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17
Q

Explain channel proteins

A

Molecules can easily flow
Like water and oxygen- easier for them to diffuse

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18
Q

Carrier proteins_______

A

change shape

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19
Q

True or false: Carrier proteins are always open?

A

False

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20
Q

Explain the process of carrier proteins

A

bind to substance -> protein shape changes-> bound molecule moves into/put of cell

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21
Q

What is osmosis?

A

molecules move from high->low concentration across semi-permeable membrane (often water)

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22
Q

What is a solute?

A

something that is dissolved in a solvent (e.g sugar)

23
Q

What is a Solvent

A

It does the dissolving (e.g. water)

24
Q

What is Tonicity?

A

water potential of 2 solutions separated by semipermeable membrane
Solute concentration outside the cell and water respond the that

25
Q

What is Osmolarity?

A

total solute concentration of the solution

26
Q

What is Hypotonic?

A

extracellular fluid has lower solute concentration than cell; water enters cell ( expands)

27
Q

What is Hypertonic?

A

extracellular fluid has high solute concentration than cell; water exits cell (shrinks)

28
Q

What is Isotonic?

A

solute concentration of cell= sae as extracellular fluid

29
Q

True or False: Active Transport does not require ATP

A

False

30
Q

Define active transport

A

Primary active transport moves ions across a membrane and creates an electrochemical gradient ( charge +/- concentration diffusions). Change the shape and opening of the protein to allow the molecule to enter or exit requires energy

31
Q

Electrochemical gradient vs. Concentration gradient:

A

With active transport there is usually an electrochemical gradient that exists
A charged difference because ions involved
Ions or molecules can be excluded or the cell can accumulate them
Equilibrium does not have to be accomplished
Concentration gradient is a chemical gradient
Difference of molecules on one side of the membrane compared to the other

32
Q

What is the function of a Uniporter?

A

arries 1 molecule or ion in one direction

33
Q

What is the function of symporters?

A

Carries 2 different molecules or ions both in the same direction

34
Q

What is the function of Antiport?

A

Carrie 2 different molecules or ions in different directions
One moves in and one moves out

35
Q

What is the function of bulk movement?

A

Some molecules are simply too large or exit a cell by passive or active transport
Some molecules are needed in bulk, not one at a time

36
Q

Bulk movement involves_______

A

the formation of vesicles that either use the cell membrane or recycle the cell membrane

37
Q

What is Endocytosis?

A

When a molecule(s) enters the cell

38
Q

What is exocytosis?

A

When a molecule(s) exits the cell

39
Q

Bulk movement always_________

A

Recycles the cell membrane

40
Q

What is Phagocytosis?

A

When one cell consumes another “ cell eating”

41
Q

What is pinocytosis?

A

A cell drinks a mass of water “ cell drinking”

42
Q

What is Receptor-mediated endocytosis?

A

Proteins can bond to the receptors on surface of membranes and if it fits will form a vesicle around it to take it in

43
Q

Viruses are able to enter the cell through___________

A

Receptor-mediated endocytosis

44
Q

Explain the process of phagocytosis

A

Cells ingest large particles or even cells by enclosing them in an extension of the cell membrane and budding off a new vaculos
Cell eating
CELL MEMBRANE IS USED TO ENVELOPE
Endosymbiosis is a unique example

45
Q

Explain the process of pinocystosis

A

Cell takes in molecules by drinking in the extracellular fluid
Cell drinking

46
Q

Explain the process of receptor-mediated endocytosis

A

Receptor proteins in the plasma membrane ensure only targeted substances are brought into the cell
A vesicle forms around and the substance is brought in

47
Q

Explain the process of exocystosis

A

Water material for example is enveloped in a vesicle and fuses with the plasma membrane
Waste materials is expelled into the extracellular space
Secretion of proteins and neurotransmitters

48
Q

What imparts rigidity and some resistance to flow?

A

cholesterol

49
Q

The recognition of self facilitated by the plasma membrane plays an important role in ________.

A

the immune response

50
Q

The surface of the plasma membrane is ________ due to the ________.

A

hydrophilic; phospholipids

51
Q

All types of endocytosis include ________.

A

he formation of a plasma membrane pocket around the target

52
Q

________ form specialized sites on the cell surface that allow cells to recognize each other.

A

Carbohydrates

53
Q

In ________, the energy required is provided by an electrochemical gradient.

A

secondary active transport

Biology 101 (16 decks)

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