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Cell Biology > Lab Exam 2 > Flashcards

Lab Exam 2 Flashcards

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0
Q

What is chemical potential?

A

Measure of free energy available to do the work of moving a mole of molecules from one location to another

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1
Q

What is the law of diffusion?

A

Molecules move from areas of higher chemical potential to areas of lower chemical potential

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2
Q

Give an example of a time chemical potential is used

A

To move a molecule through a cell membrane

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3
Q

The relationship between concentration of dissolved substance and chemical potential is what?

A

Proportional

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4
Q

Molecules move from areas of _____ concentration to areas of _____ concentration

A

High concentration to Low concentration

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5
Q

What is osmosis?

A

Movement of water molecules from regions if higher water potential to regions of lower water potential across a selectively permeable membrane

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6
Q

What is water potential?

A

Measure of the chemical potential of water molecules

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7
Q

What is water potential affected by?

A

Amount of other substances dissolved in water

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8
Q

The ______ the concentration of a dissolved solute in water, the _____ the water potential

A

Greater, lower

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9
Q

What is the water potential of pure water?

A

0

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10
Q

When solute is added to pure water, does the water potential become negative or positive

A

Negative

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11
Q

Water moves across membranes toward areas with ______ concentration of solutes, where the water potential is ______

A

Higher, lower

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12
Q

Give two examples of passive transport

A

Diffusion

Osmosis

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13
Q

What does passive transport mean?

A

Molecules are moving down concentration or free energy gradients

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14
Q

What is active transport?

A

Moving a molecule against a gradient and requiring energy

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15
Q

What movement is exhibited in Brownian movement?

A

Jiggling

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16
Q

Can you see water molecules in a microscope ?

A

No

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17
Q

Would an increase in temperature increAse or decrease the rate of Brownian movement?

A

Increase

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18
Q

Why are molecules in liquids in constant movement?

A

Due to their kenetic energy

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19
Q

What is the rate of diffusion controlled by? (4 things)

A

The size of the diffusing particle
The temperature
The viscosity of the medium
The concentration gradient

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20
Q

Does the net movement of molecules slow down as equilibrium is reached? Why?

A

Yes, because the concentration gradient is smaller

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21
Q

What can you say about the chemical potential of pigment molecules at different distances from the center of a spreading pigment spot

A

At the center the chemical potential is higher, away from the center is lower

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22
Q

How is chemical potential of pigment molecules related to their rate of movement?

A

As the chemical potential decreases, the rate of movement slows down.

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23
Q

Does net diffusion eventually come to an end? Why?

A

Yes, because equilibrium was reached

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24
Q

What type of membrane does a cell membrane have?

A

Semi permeable

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25
Q

What molecules can move freely through the cell membrane?

A

Hydrophobic solute molecules, water, small polar uncharged molecules

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26
Q

Solutes diffusing through a selectively permeable membrane diffuse from an area of ______ chemical potential to an area of _____ chemical potential

A

High,

Lower

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27
Q

What happens it two solutions diffusing contain equal concentrations of solute?

A

Their chemical potentials are equal and no net movement of particles occurs

28
Q

In a laboratory how can molecules of different sizes be separated?

A

Molecules of different sizes can be separated by dialysis using artificial semipermeable membranes

29
Q

How do living membranes select molecules of differing sizes to go through them?

A

They change their pore size by altering lipid and protein content

30
Q

What can you say about the effects of molecular size on the diffusion of molecules across a semi permeable membrane?

A

If the molecule is very big then it won’t go through the membrane

31
Q

What is an isosmotic/isotonic medium?

A

Medium that has the same concentration of osmotically active particles as are present inside the cell

32
Q

What is a hyperosmotic/hypertonic medium?

A

Medium that has higher concentration of osmotically active particles that forces a cell to lose water by osmosis to the medium

33
Q

What is plasmolysis and what does it occur in?

A

Plasmolysis is when a cell becomes dehydrated and shrinks and it occurs in plants

34
Q

What is crenation and what does it occur in?

A

Crenation is when a cell becomes dehydrated and shrinks. It occurs in red blood cells

35
Q

What is a hypoosmotic/hypotonic medium?

A

Medium that has a lower concentration of osmotically active particles.

36
Q

What is turgidity and in what does it occur?

A

Turgidity is when a cell gains water by osmosis and swells

37
Q

What is hemolysis? And in what does it occur?

A

Hemolysis is when a cell gains water and swells and can continue to gain water until it bursts. It occurs in red blood cells

38
Q

What does lysed mean?

A

The cell burst

39
Q

What is the relationship between the increase in mass and the molarity of sucrose in the dialysis bag?

A

There’s a proportional relationship

40
Q

If two solutions are isotonic to each other, how do their solute concentrations compare?

A

They are the same

41
Q

What are enzymes?

A

Proteins that control reactions in cells

42
Q

What are biological catalysts?

A

Accelerate metabolic reactions to a biologically useful rate by lowering activation energy.

43
Q

Enzymes are ______ proteins

A

Globular

44
Q

Enzymes folds create the _____ site

A

Active

45
Q

Each amino acid has one specific _______

A

Substrate

46
Q

What is the alteration of the active site called?

A

An induced fit

47
Q

Any structural change in an enzyme will __________ it by altering its ________ and _______ the reaction rate

A

Denature
Active site
Slowing down/stopping

48
Q

What is an inhibitor?

A

A molecule that binds to the active site preventing a substrate from bonding and prevents chemical reactions

49
Q

Enzymes function best at optimal _______ and ______

A

Temperature

pH

50
Q

What enzyme is found in living tissues?

A

Catalase

51
Q

What does the enzyme catalase do?

A

Breaks down hydrogen peroxide in cells

52
Q

What is hydrogen peroxide broken down into?

A

Oxygen and water

53
Q

The presence/absence of what gas will determine if a reaction is taking place

A

O2

54
Q

What is the enzyme responsible for the browning process of fruits?

A

Catecholase

55
Q

What is the substrate of catecholase?

A

Catechol

56
Q

When does the browning reaction begin?

A

When the enzyme and substrate are brought together by cell damage in the presence of oxygen.

57
Q

Why does oxygen start the browning process in fruit? What molecule does it form?

A

Oxygen promotes the exchange of electrons and pulls electrons from catechole which forms benzoquinone.

58
Q

What does heat do to an enzymatic reaction?

A

Denatures the protein and decreases/stops reaction

59
Q

Explain what happens when a protein is denatured

A

It loses shape, substrate can no longer go in it, no more active area = no rx

60
Q

What is solid milk called?

A

Curd

61
Q

What is liquid part of milk called?

A

Whey

62
Q

What enzyme is required to produce cheese curd?

A

Rennin

63
Q

What is the major protein in milk?

A

Casein

64
Q

What does rennin do to casein?

A

Converts it to paracasein

65
Q

What does para casein do?

A

Clots or curds the milk.

66
Q

What is velocity?

A

Rate of rx

67
Q

Why is there no increase in reaction rate once the saturation level of the substrate is reached?

A

All enzymes activation sites are occupied so no further substrate can be used

68
Q

Does an increase in enzyme concentration influence the mass of curd produced?

A

Yes the more concentrated the more curd produced

Cell Biology (13 decks)

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