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Bio 101 > Chapter 5 > Flashcards

Chapter 5 Flashcards

Structure and Function of Plasma Membranes

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1
Q

active transport

A

method of transporting material that requires energy

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2
Q

amphiphilic

A

molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments

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3
Q

antiporter

A

transporter that carries two ions or small molecules in different directions

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4
Q

aquaporin

A

channel protein that allows water through the
membrane at a very high rate

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5
Q

carrier protein

A

membrane protein that moves a substance
across the plasma membrane by changing its own shape

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6
Q

caveolin

A

protein that coats the plasma membrane’s
cytoplasmic side and participates in the liquid uptake process by potocytosis

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7
Q

channel protein

A

membrane protein that allows a substance to pass through its hollow core across the plasma membrane

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8
Q

clathrin

A

protein that coats the plasma membrane’s inward facing surface and assists in forming specialized structures, like coated pits, for phagocytosis

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9
Q

concentration gradient

A

area of high concentration
adjacent to an area of low concentration

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10
Q

diffusion

A

passive transport process of low-molecular
weight material according to its concentration gradient

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11
Q

electrochemical gradient

A

a combined electrical and
chemical force that produces a gradient

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12
Q

electrogenic pump

A

pump that creates a charge imbalance

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13
Q

endocytosis

A

type of active transport that moves substances, including fluids and particles, into a cell

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14
Q

exocytosis

A

process of passing bulk material out of a cell

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15
Q

facilitated transport

A

process by which material moves
down a concentration gradient (from high to low
concentration) using integral membrane proteins

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16
Q

fluid mosaic

A

model describes the plasma membrane’s structure as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids,
respectively), resulting in a fluid character (fluidity)

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17
Q

glycolipid

A

combination of carbohydrates and lipids

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18
Q

glycoprotein

A

combination of carbohydrates and proteins

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19
Q

hydrophilic

A

molecule with the ability to bond with water;
“water-loving”

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20
Q

hydrophobic

A

molecule that does not have the ability to
bond with water; “water-hating”

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21
Q

hypertonic

A

situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell

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22
Q

hypotonic

A

situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell

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23
Q

integral protein

A

protein integrated into the membrane structure that interacts extensively with the membrane lipids’ hydrocarbon chains and often spans the membrane

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24
Q

isotonic

A

situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net water movement into or out of the cell

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25
Q

osmolarity

A

total amount of substances dissolved in a specific amount of solution

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26
Q

osmosis transport
passive transport

A

of water through a semipermeable
membrane according to the water’s concentration gradient across the membrane that results from the
presence of solute that cannot pass through the membrane

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27
Q

passive transport

A

method of transporting material
through a membrane that does not require energy

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28
Q

peripheral protein

A

protein at the plasma membrane’s
surface either on its exterior or interior side

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29
Q

pinocytosis

A

a variation of endocytosis that imports
macromolecules that the cell needs from the extracellular
fluid

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30
Q

plasmolysis

A

detaching the cell membrane from the cell wall
and constricting the cell membrane when a plant cell is in
a hypertonic solution

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31
Q

potocytosis

A

variation of pinocytosis that uses a different
coating protein (caveolin) on the plasma membrane’s
cytoplasmic side

32
Q

primary active transport

A

active transport that moves ions
or small molecules across a membrane and may create a
difference in charge across that membrane

33
Q

pump

A

active transport mechanism that works against
electrochemical gradients

34
Q

receptor-mediated endocytosis

A

variation of endocytosis
that involves using specific binding proteins in the
plasma membrane for specific molecules or particles, and
clathrin-coated pits that become clathrin-coated vesicles

35
Q

secondary active transport

A

movement of material that results from primary active transport to the electrochemical gradient

36
Q

selectively permeable

A

membrane characteristic that allows
some substances through

37
Q

solute

A

substance dissolved in a liquid to form a solution

38
Q

symporter

A

transporter that carries two different ions or
small molecules, both in the same direction

39
Q

tonicity

A

amount of solute in a solution

40
Q

transport protein

A

membrane protein that facilitates a
substance’s passage across a membrane by binding it

41
Q

transporter

A

specific carrier proteins or pumps that facilitate movement

42
Q

uniporter

A

transporter that carries one specific ion or molecule

43
Q

A doctor injects a patient with what the doctor thinks is an isotonic saline solution. The patient dies, and an autopsy reveals that many red blood cells have been
destroyed. Do you think the solution the doctor injected
was really isotonic?

A

No, the solution wasn’t isotonic

No, the solution must have been isotonic, as a hypotonic solution would cause water to enter the cells, thereby making them burst

44
Q

Injecting a potassium solution into a person’s blood is lethal. Capital punishment and euthanasia
utilize this method in their subjects. Why do you think a potassium solution injection is lethal?

A

Cells typically have a high concentration of potassium, and with injecting this it makes your blood toxic

45
Q

If the pH outside the cell decreases, would you expect the amount of amino acids transported into the
cell to increase or decrease?

A

If the pH outside the cell decreases, the transport of amino acids into the cell would increase.

46
Q

Which plasma membrane component can be either
found on its surface or embedded in the membrane
structure?

A

protein

47
Q

Which characteristic of a phospholipid contributes to the fluidity of the membrane?

A

double bonds in the fatty acid tail

48
Q

What is the primary function of carbohydrates attached to the exterior of cell membranes?

A

identification of the cell

49
Q

A scientist compares the plasma membrane composition of an animal from the Mediterranean coast with one from the Mojave Desert. Which hypothesis is most likely to be correct?

A

The cells from the Mojave Desert animal will have a higher cholesterol concentration in the plasma membranes.

50
Q

Water moves via osmosis _________.

A

from an area with a high concentration of other solutes to a lower one

51
Q

The principal force driving movement in diffusion is the__________.

A

concentration gradient

52
Q

What problem is faced by organisms that live in fresh
water?

A

Their bodies tend to take in too much water

53
Q

In which situation would passive transport not use a
transport protein for entry into a cell?

A

oxygen moving into a cell after oxygen deprivation

54
Q

Active transport must function continuously because
__________.

A

diffusion is constantly moving solutes in opposite
directions

55
Q

How does the sodium-potassium pump make the interior of the cell negatively charged?

A

by expelling more cations than are taken in

56
Q

What is the combination of an electrical gradient and a concentration gradient called?

A

electrochemical gradient

57
Q

What happens to the membrane of a vesicle after exocytosis?

A

It fuses with and becomes part of the plasma membrane

58
Q

Which transport mechanism can bring whole cells into a
cell?

A

phagocytosis

59
Q

In what important way does receptor-mediated
endocytosis differ from phagocytosis?

A

It transports only small amounts of fluid.

60
Q

Many viruses enter host cells through receptor-mediated
endocytosis. What is an advantage of this entry strategy?

A

The virus only enters its target host cell type.

61
Q

Which of the following organelles relies on exocytosis to
complete its function?

A

Golgi apparatus

62
Q

Imagine a cell can perform exocytosis, but only minimal
endocytosis. What would happen to the cell?

A

The plasma membrane would increase in size over
time.

63
Q

Why is it advantageous for the cell membrane to be fluid
in nature?

A

The fluid characteristic of the cell membrane allows greater flexibility to the cell than it would if the membrane were rigid. It also allows the motion of membrane components, required for some types of membrane transport.

64
Q

Why do phospholipids tend to spontaneously orient
themselves into something resembling a membrane?

A

The hydrophobic, nonpolar regions must align with each other in order for the structure to have minimal potential energy and, consequently, higher stability. The fatty acid tails of the phospholipids cannot mix with water, but the phosphate “head” of the molecule can. Thus, the head orients to water, and the tail to other lipids.

65
Q

How can a cell use an extracellular peripheral protein as
the receptor to transmit a signal into the cell?

A

In an extracellular space, the other molecules will be bound with peripheral proteins. Though they do not have a transmembrane domain, peripheral proteins can bind to other molecules.

In order to pass the signal into the cell, they must correlate with integral membrane proteins.

66
Q

Discuss why the following affect the rate of diffusion:
molecular size, temperature, solution density, and the
distance that must be traveled.

A

The rate of diffusion is affected by molecular size, temperature, solution density, and the distance molecules must travel, with larger molecules, higher density, and greater distances slowing down diffusion, while higher temperatures speed it up

67
Q

Why does water move through a membrane?

A

The water moves through a membrane when it is not in an equilibrium state and when it doesn’t have equal concentrations on each side of the membrane.

68
Q

Both of the regular intravenous solutions administered
in medicine, normal saline and lactated Ringer’s
solution, are isotonic. Why is this important?

A

The intravenous solutions ensure the concentration of the solution which will be injected and It also compares it to blood plasma. Additionally, It ensures that there is no change in the size of the cell.

69
Q

Describe two ways that decreasing temperature would
affect the rate of diffusion of molecules across a cell’s
plasma membrane.

A

Two ways that decreasing temperature would affect the rate of diffusion of molecules across a cell’s plasma membrane

Decreases the kinetic energy of the molecules in the plasma membrane.
Increases the density of the plasma membrane

Due to a decrease in temperature the kinetic energy of the plasma membrane will also be decreased so that the rate of diffusion alters.

70
Q

A cell develops a mutation in its potassium channels
that prevents the ions from leaving the cell. If the cell’s
aquaporins are still active, what will happen to the cell?
Be sure to describe the tonicity and osmolarity of the
cell.

A

If the cell’s aquaporins are active then Osmolarity increases inside the cell by creating the hypotonic solution.

Explanation

If the mutation occurs in the potassium channel, accumulation of the potassium ions occurs that is pumped into the cell due to this osmolarity increases inside the cell by creating the hypotonic solution.

As plasma membrane is selectively permeable to water so that water will flow into the cell by the aquaporins, If the concentration of potassium is high, then enough water will flow into the cell to lyse it.

How an extracellular solution develops changes in a cell volume by affecting the osmosis is described by the tonicity whereas the total solute concentration of the solution is described by the osmolarity.

71
Q

Where does the cell get energy for active transport
processes?

A

The cell uses energy stored in it in the form of ATP (adenosine triphosphate).

72
Q

How does the sodium-potassium pump contribute to
the net negative charge of the interior of the cell?

A

The sodium-potassium pump contributes to the net negative charge inside the cell by the electrochemical gradient.

Explanation

The concentration gradient of sodium in the cell tends to move into the cell and the electrical gradient of Na+ moves it inside to the negative charge but this situation is different for other elements like potassium in this situation electrical gradients of the K+ move into the cell but the concentration gradients move K+ outside the cells.

73
Q

Glucose from digested food enters intestinal epithelial
cells by active transport. Why would intestinal cells use
active transport when most body cells use facilitated
diffusion?

A

Intestinal cells use active transport because it prevents the backflow of glucose into the gut.

Explanation

When glucose enters the intestinal cells through active transport it prevents the backflow of the glucose into the gut and it also ensures the transportation of the glucose continuously even after the presence of the high level of glucose is in the intestinal cells.

74
Q

The sodium/calcium exchanger (NCX) transports
sodium into and calcium out of cardiac muscle cells.
Describe why this transporter is classified as secondary
active transport.

A

When there is a use of energy in transporting the particles then it’s known as active transportation.

Explanation

In the Secondary active transport sodium ions and some other compounds are brought into the cell. Because of the primary active transport process, sodium ion concentrations start building outside of the plasma membrane which creates an electrochemical gradient.

75
Q

Why is it important that there are different types of proteins in plasma membranes for the transport of materials into and out of a cell?

A

There are specialized channels that facilitate the passage of materials through the membrane. So to pass all types of materials, the presence of proteins are must, inside and outside of the plasma membrane.

Explanation

The proteins are very useful channels as they work only for a specific ion or material which is required by the cell at a certain moment. If a single channel allows all types of materials through it then it might bring unwanted products into the cell and hinder its functions or damage the cell. Thus the specific proteins allow specific products and this helps in the normal functioning of the cell.

76
Q

Why do ions have a difficult time getting through
plasma membranes despite their small size?

A

Ions are charged particles present in a solution. The charge is either positive or negative. As the cell membrane is semipermeable, it doesn’t allow charged, hydrophilic ions to pass through it.

Explanation

As the cell membrane is semipermeable thus it doesn’t allow charged, hydrophilic ions to pass through it. Thus charged ions need special Proteins through which they can pass through and enter cell plasma.

Bio 101 (9 decks)

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