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Bio I - 1 > Bio I - 6 > Flashcards

Bio I - 6 Flashcards

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Biology 101 flashcards
1
Q

What is the plasma membrane?

A

It is a boundary that separates the living cell from its surroundings

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2
Q

What is selective Permeability?

A

It means that the plasma membrane allows some substances to cross it more easily than others

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3
Q

What is the most abundant lipid in the plasma membrane?

A

Phospholipids

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4
Q

What does ampithetic molecule mean?

A

It contains hydrophobic and hydrophilic regions

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5
Q

What does the fluid mosaic model state?

A

That a membrane is a fluid structure with a mosaic of various proteins embedded in it

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6
Q

What are membranes made of?

A

Proteins and lipids

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7
Q

What is a freeze fracture study?

A

Freeze fracture is a specialized preparation technique that splits a membrane along the middle of the phospholipid bilayer

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8
Q

What did the phrase fracture study support?

A

The fluid mosaic model

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9
Q

True or false
Phospholipids in the plasma membrane can move within the bilayer. 

A

True

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10
Q

How do the lipids and proteins move in the bilayer?

A

They drift laterally

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11
Q

Does a molecule ever flip flop transversely across the membrane?

A

Rarely

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12
Q

What happens to the membrane when temperatures cool?

A

Membranes switch from a fluid state to a solid state

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13
Q

At What temperature does the membrane solidify?

A

It depends on the type of lipid

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14
Q

Are membranes rich and unsaturated fatty acids are _______ than those rich in saturated fatty acids. 

A

More fluid

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15
Q

True or false
Membranes must be more solid to work properly.

A

False. They must be more fluid

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16
Q

What is cholesterol?

A

It is a steroid

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17
Q

How does cholesterol affect the membrane?

A

At warm temperatures cholesterol restrains movement of phospholipids. At cool temperatures it maintains fluidity by preventing tight packing.

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18
Q

What do proteins determine?

A

Most of the membrane specific functions

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19
Q

What is a membrane composed of?

A

It is a collage of different proteins embedded in the fluid matrix of the lipid bilayer

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20
Q

What are peripheral proteins?

A

They are proteins that are bound to the surface of the membrane

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21
Q

What are integral proteins?

A

They are proteins that penetrate the hydrophobic core

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22
Q

What are integral proteins called that span the membrane?

A

Transmembrane proteins

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23
Q

The Hydrophobic regions of an integral proteins consist of one or more stretches of _________ often coiled into __________

A

Non polar amino acids
Alpha helices

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24
Q

What are the six major functions of membrane proteins?

A

Transport
Enzymatic activity
Signal transduction
Cell cell recognition
Intercellular joining
Attachment to the cytoskeleton an extra cellular matrix

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25
Q

When is the asymmetrical distribution of proteins lipids and associated carbohydrates in the plasma membrane determined?

A

When the membrane is built by the ER and Golgi apparatus

26
Q

True or false.
Hydrophobic nonpolar molecules such as hydrocarbons can dissolve in the lipid bilayer and pass through the membrane rapidly

A

True

27
Q

Do polar molecules cross the membrane easily?

A

No

28
Q

What do transport proteins do?

A

They allow for passage of hydrophilic substances across the membrane

29
Q

What are channel proteins?

A

They are a type of transport proteins that have a hydrophilic channel that certain molecules or ions can use as a tunnel

30
Q

What are aquaporins?

A

They are channel proteins that facilitate the passage of water

31
Q

What are carrier proteins?

A

They are transport proteins that bind to molecules and change the shape to shuttle them across the membrane

32
Q

What is a passive transport?

A

It is the movement of ions and other atomic or molecular substances across cell membranes without need of energy input

33
Q

What is active transport?

A

It is the movement of ions or molecules across the cell membrane into a region of higher concentration assisted by enzymes and requiring energy

34
Q

What is diffusion?

A

Diffusion is the tendency for molecules to spread out evenly into the available space

35
Q

What is dynamic equilibrium?

A

At dynamic equilibrium as many molecules cross one-way as cross in the other direction

36
Q

Diffusion follows the natural concentration gradient. What is the natural concentration gradient?

A

When a molecule moves from higher concentration to lower concentration of molecules

37
Q

Does diffusion require input of energy And a carrier protein?

A

No

38
Q

What is osmosis?

A

Osmosis is the diffusion of water across a selectively permeable membrane

39
Q

Water diffuses across a membrane from the region of _____ to the region of _____

A

Lower solute concentration
Higher solute concentration

40
Q

What is tonicity?

A

What is the ability of a solution to cause a cell to gain or lose water

41
Q

What is a isotonic solution?

A

The solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

42
Q

What is a hypertonic solution?

A

When the solute concentration is greater than the inside of the cell and therefore the cell loses water

43
Q

What is a hypotonic solution?

A

The solute concentration is less than that inside the cell and therefore the cell gains water

44
Q

What happens when a plant cell is in a hypotonic solution?

A

It swells until the wall opposes uptake; the cell is now turgid/ firm

45
Q

What happens to a plant cell and an isotonic state?

A

There is no net movement of water into the cell; the cell becomes flaccid/ limp and the plant may wilt

46
Q

What is facilitated diffusion?

A

It is when transport proteins speed the passive movement of molecules across the plasma membrane

47
Q

What do channel proteins include?

A

Aqua Porins, for facilitated diffusion of water
Ion channels that open or close in response to a stimuli/gated channels

48
Q

What to channel proteins provide?

A

They provide corridors that allow a specific molecules or ions across the membrane

49
Q

What is active transport?

A

Active transport moves substances against their concentration gradient

50
Q

Does active transport require energy?

A

Yes
The energy is usually in the form of ATP

51
Q

What is active transport performed by?

A

The specific proteins embedded in the membranes

52
Q

What does active transport allow cells to do?

A

It allows cells to maintain concentration gradients that differ from their surroundings

53
Q

What is one type of active transport system?

A

The sodium potassium pump

54
Q

What is bulk transport?

A

It Is the transport of larger molecules across the membrane

55
Q

What does the bulk transport process require?

A

It is an active transport process that requires input of energy and a carrier protein

56
Q

What are two bulk transport systems?

A

Exocytosis and endocytosis

57
Q

What is exocytosis?

A

It is when transport vesicles migrate to the membrane, fused with it, and release their contents

58
Q

What type of cells use exocytosis to export their products?

A

Secretory cells

59
Q

What is endocytosis?

A

The cell takes in macromolecules by forming vesicles from the plasma membrane

60
Q

What are the three types of endocytosis?

A

Phagocytosis – larger molecules (cellular eating), pinocytosis – smaller molecules (cellular drinking)
Receptor mediated endocytosis

Bio I - 1 (10 decks)

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