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Biology > Membranes > Flashcards

Membranes Flashcards

1
Q

What are cell membranes formed from?

A

A phospholipid bilayer

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2
Q

What does the molecule have?

A

A head and tail

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3
Q

The head is hydrophilic which means it is what?

A

Water loving (phosphate part)

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4
Q

The tail is hydrophobic which means what?

A

Water fearing (lipid part)

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5
Q

The inside and outside of a cell is mostly water, so the phospholipid molecule take on what?

A

A specific orientation

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6
Q

What else does the membrane contain that spans the whole cross-section?

A

Proteins; transmembrane proteins

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7
Q

The membrane is what?

A

Not static, the molecules are not fixed in place

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8
Q

Because the molecules are not static, they are allowed to do what?

A

Freely slide and drift around and past one another

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9
Q

What does the cell membrane follow?

A

The fluid mosaic model

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10
Q

What is facilitated diffusion?

A

A type of passive transport

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11
Q

What is facilitated diffusion used for?

A

The movement of large molecules across the membrane with the help of transmembrane proteins

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12
Q

What are the two types of transmembrane proteins?

A

Carrier proteins and channel proteins

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13
Q

What are carrier proteins?

A

Act as a lock where a molecule is the key, only one type of molecule can work, the molecule fits in a shape specific region of the proteins which induces a conformational shift in the proteins, this transports the molecule across the membrane (no energy required)

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14
Q

What are channel proteins?

A

Essentially a tunnel that let ions and water through, stuff substance specific

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15
Q

What is active transport?

A

The opposite of passive transport

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16
Q

Where do molecules move in active transport?

A

From an area of low concentration to an area of high concentration

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17
Q

The movement of active transport is?

A

Against the concentration gradient

18
Q

Is energy required for active transport?

A

Yes, ATP

19
Q

What kind of molecules simply do active transport?

A

Small molecules (pumps)

20
Q

Large molecules are transported across the membrane in what?

A

Vesicles (formed from the cell membrane pinching in or by the Golgi)

21
Q

What is exocytosis for?

A

Secretion and waste removal; a vesicle moves toward the cell membrane, fuses with it and releases its contents

22
Q

What is endocytosis for?

A

To move large substances into the cell; solids by phagocytosis (eating) and liquids by pinocytosis (drinking)

23
Q

What is the function of the membrane?

A

Regulating the movement of substances into and out of a cell

24
Q

What are cells?

A

Semi-permeable; some substances can move in + out while others cannot

25
Q

What can slip directly between the phospholipid molecules?

A

Small molecules

26
Q

Large molecules and water must use what to cross the membrane?

A

Transmembrane proteins

27
Q

What is Brownian motion?

A

Particles are in constant random motion

28
Q

What is the concentration gradient?

A

The difference in concentration between two areas

29
Q

What is equilibrium?

A

When two areas have equal concentrations

30
Q

What is passive transport?

A

When molecules move across the membrane from an area of high concentration to low concentration

31
Q

What type of movement on the concentration gradient is passive transport?

A

Down the concentration gradient; doesn’t require energy

32
Q

T or F; The way one type of substance undergoes passive transport is independent of other substances

A

True

33
Q

What is diffusion?

A

Basic passive transport

34
Q

What is osmosis?

A

A special term for the passive transport of water; through specialized transmembrane proteins called aquaporins

35
Q

What are related terms?

A

Used to describe the relationship between the concentration of two areas

36
Q

What does hypotonic mean?

A

An area with less concentration

37
Q

What does isotonic mean?

A

When two areas have equal concentrations

38
Q

What does hypertonic mean?

A

An area with greater concentration

39
Q

What tends to happen to hypertonic areas?

A

They tend to gain water

40
Q

What tends to happen to hypotonic areas?

A

They tend to lose water

41
Q

What happens at equilibrium?

A

Molecular movement continues, it just means that the rates forward and back are equal

42
Q

What can happen to cells in the extreme?

A

A cell could shrivel or burst

Biology (8 decks)

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