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Biology > Cell Membranes > Flashcards

Cell Membranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

What is the main part of the membrane?

A

Phospholipid bilayer

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1
Q

Approximately how thick is the membrane?

A

7nm

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2
Q

Which end of the phospholipid do glycoproteins/lipids attach to?

A

Hydrophilic

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3
Q

What do antigens do?

A

Cause antibody reaction

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4
Q

What does cholesterol do?

A

Controls fluidity
Steroid- lipid
Makes membrane less permeable to charged/polar particles

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5
Q

Define transmembranous protein

A

Carrier protein with channel to allow transport in and out of cell

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6
Q

Define intrinsic protein

A

Protein on surface that doesn’t permeate membrane

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7
Q

What can proteins act as in the membrane?

A

Enzymes

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8
Q

What do glycoproteins do?

A

Binding site (for neurotransmitters, hormones etc)
Antigens
Stabilisation
Receptors for cell signalling

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9
Q

How can foreign microbes make detection more difficult?

A

Change the structure of their surface cell proteins

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10
Q

FLUID MOSAIC MODEL

Explain pls.

A

Fluid- molecules free to move in/out

Mosaic- made up of different proteins embedded in a phospholipid bilayer

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11
Q

Name for burst animal cell (in hypotonic solution)

A

Lysed (lysis)

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12
Q

Define tonicity

A

Difference in water concentration of two solutions separated by a semipermeable membrane

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13
Q

Define hypotonic

A

Lower concentration outside cell

Water enters

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14
Q

Define hypertonic

A

Higher concentration outside cell

Water leaves

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15
Q

Name for when cell shrinks due to water loss

A

Crenated

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16
Q

What is ATP broken down into after active processes?

A

ADP
and
Inorganic phosphate

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17
Q

Rate of diffusion depends upon what?

A

Concentration gradient
Temperature
SiZe oF PaRtiCLeS
Surface area

18
Q

What kind of particles need special pathways to cross the plasma membrane?

A

Charged/polar molecules

19
Q

What does the sodium-potassium pump do?

A

Aids the active transport of sodium and potassium in/out of cells against the concentration gradient. Uses ATP

20
Q

When one ATP is broken down in the sodium-potassium pump, what happens?

A

Two potassium atoms are taken in

21
Q

When is facilitated diffusion used?

A

To transport LARGE and/or highly charged ⚡ particles

22
Q

Facilitated diffusion moves substances _____ the concentration gradient

A

Down

23
Q

Two types of facilitated diffusion

A

Channel proteins change shape

Ion specific channels

24
Q

Conditions for high water potential?

A

Solution with:
A lot of water ☔
Under a lot of pressure

25
Q

Three mechanisms of cell signalling?

A

1⃣Receptor acts as ION CHANNEL
2⃣Receptor activates G-PROTEIN
3⃣Receptor acts as ENZYME

26
Q

How do ion channels work?

A

Chemical signal activates proteins, which open to form channel

27
Q

How does g-protein activation work?

A

Signal molecule➡ receptor➡ g-protein

28
Q

How do receptor-enzyme hybrids work?

A

Signal molecule brings two parts together, activates cytoplasm-side enzymes, causes response.

29
Q

Mechanism of endocytosis?

A

Plasma membrane surrounds particle by folding. Makes vesicle inside.

30
Q

Mechanism of exocytosis

A

Vesicles pinch off from the Golgi, travel through plasma membrane, fuse with membrane and release contents.

31
Q

Why doesn’t H2O need facilitated diffusion?

A

Although it’s polar, it’s small enough to pass through transmembranous proteins.

32
Q

True or false

Plasma membranes can allow an electrical current to pass along them

A

True

33
Q

Why are the heads of phospholipids hydrophilic?

A

They have a tiny charge which attracts the water

34
Q

How does cholesterol regulate fluidity?

A

Ensures plasma membrane doesn’t become too stiff when cold or too fluid when hot

35
Q

How do small, non-polar substances enter cell?

A

Passive diffusion

36
Q

How do large substances enter?

A

Endocytosis using ATP

37
Q

How do polar substances enter?

A

Facilitated diffusion

38
Q

Differences between active transport and facilitated diffusion

A

FD not against conc grad

AT uses ATP

40
Q

Function of plasma membrane

A

Control in/out
Cell signalling
Receptor

41
Q

Role of membranes inside cells

A

Compartmentalisation
Inc surface area
Vesicles
Partially permeable- control in/out of organelle

42
Q

Outline mechanism of exocytosis

A

Vesicle forms at Golgi

Transported along microtubules

43
Q

How do phospholipids control fluidity of plasma membrane?

A

When unsaturated, membrane is more fluid
Because
The kink in the tail of the unsaturated lipid means the molecules can’t sit closely together

Biology (14 decks)

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