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Bio 112 > Chapter 5- Membranes > Flashcards

Chapter 5- Membranes Flashcards

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Biology 101 flashcards
1
Q

Cellular communication

A

One cell membrane releases something to another cell membrane

Membrane to membrane interactions

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2
Q

Transporters

A

How to get things through a cell membrane

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3
Q

Motion at the Cellular Level

A

Diffusion

Osmosis

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4
Q

Membranes

A

Cell membranes are fluid=Not a solid structure

Membrane fluid as in having ripples and waves

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5
Q

Membrane Structure

A

51% of cell membrane is made up of phospholipids

Phospholipids arranged in a bilayer

Globular proteins inserted in the lipid bilayer

Fluid mosaic model- mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond

If the cell membrane is too fluidiy then holes may form

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6
Q

Phospholipids

A

Structure consists of

Glycerol- a 3-carbon polyalcohol

2 fatty acids attached to the glycerol
Nonpolar and hydrophobic

Phosphate group attached to the glycerol
Polar and hydrophilic

Spontaneously forms a bilayer
Fatty acids are on the inside
Phosphate groups are on both surfaces

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7
Q

Saturated Fatty Acids

A

Carbon has no double bonds

As you increase temperature, you need to be more saturated to be molecularly stable

Saturated fats are found in organisms that are warm blooded ( around 98 F= animals)

Because saturated fats are able to handle higher temperatures they are commonly seen in warm blooded animals

Solid at room temperatures ( ex: Butter)

Saturated fats are able to handle high temperatures due to its membrane structure

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8
Q

Unsaturated Fatty Acids

A

Move fewer total Hydrogens

Some of the carbons form a double bond

The carbon double bonds cause a bend at the legs

Unsaturated fats are more commonly in organisms at or below 70 F

Cold blooded organisms have more unsaturated fats

At room temperature a fluid ( ex: Olive Oil)

As you take unsaturated fats and increase temperature, they become molecularly unstable

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9
Q

Where is the force coming from that holds the phospholipids together?

A

The nonpolarity of the tails cause them to stick together as one

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10
Q

Environmental Influences

A

Saturated fatty acids make the membrane less fluid than unsaturated fatty acids

“Kinks” introduced by the double bonds keep them from packing tightly

Most membranes also contain sterols such as cholesterol, which can either increase or decrease membrane fluidity, depending on the temperature

Warm temperatures make the membrane more fluid than cold temperatures

Cold tolerance in bacteria due to fatty acid desaturases

Temperature is the environmental influence that interferes with the cell membrane

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11
Q

Do cholesterol and saturated fats correlate with each other?

A

Yes

Cholesterol is found in warm blooded things

Cholesterol has the same affect as saturation- It changes membrane fluidity

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12
Q

Cellular Membranes have 4 components

A
  1. Phospholipid Bilayer
  2. Transmembrane Protein
  3. Interior Protein Network
  4. Cell Surface Markers
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13
Q

Phospholipid Bilayer

A

Flexible matrix, barrier to permeability

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14
Q

Transmembrane Proteins

A

Integral membrane proteins

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15
Q

Interior Protein Network

A

Peripheral membrane proteins

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16
Q

Cell Surface Markers

A

Glycoproteins and Glycolipids

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17
Q

The Six Main Roles of the Proteins in the Cell Membrane

A
  1. Transport
    How we get things across the cell membrane
  2. Enzyme
    Speed up changes
  3. Cell Surface Receptor
    Hormones
  4. Cell Surface Identity Marker
    For blood groups: Specific carbos outside the cell membrane that act as “identity badges”
  5. Cell to Cell Adhesion
    Anchoring junction
  6. Attachment to the cytoskeleton
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18
Q

What can move through the cell membrane?

A

Water soluble molecules can’t move through the cell membrane

Ions can’t get through because they are charged

Small, nonpolar molecules can get through the cell membrane

Fat soluble molecules can get through the cell membrane

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19
Q

Transmembrane Protein Structure

A

The “design” of a transmembrane protein

Nonpolar regions of the protein are embedded in the interior of the bilayer

Polar regions of the protein protrude from both sides of the bilayer

Transmembrane domain
Spans the lipid bilayer

Proteins need only a single transmembrane domain to be anchored in the membrane, but they often have more than one such domain

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20
Q

Difference between Passive and Active Transport

A

Passive: Transport that does not require energy

Active: Carriers that require energy to work (ATP)

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21
Q

Transporters

A

2 general types of transporters

  1. Channels (always passive)
  2. Carriers (can be passive or active)
  3. The only way ions can pass through the cell membrane
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22
Q

Channels

A

Holes- Protein holes that hold open a gap

Channel proteins are “free” passive transport

There is a variation in the diameter of the channel, which determines what goes through

The size and charge of the channel determines what goes through

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23
Q

Carriers

A

Can be either Active or Passive

Has to bind (Hydrogen Bonding) to transmembrane protein

  1. Changes the shape
  2. The change in the shape allows the carrier to push the particle through
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24
Q

Channel Protiens

A

Function as holes in the membrane that let certain molecules pass down their concentration gradient

Are always categorized as “passive” because they do not use ATP

They use diffusion instead

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25
Q

Diffusion

A

The force that drives things through a fluid

Spreads out (equally spaced) from high concentration to low concentration

Causes channel proteins to work

Movement of molecules from high concentration to low concentration

Will continue until the concentration is the same in all regions

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26
Q

Passive Transport

A

Movement of molecules through the membrane in which:

No additional energy is required

Molecules move in response to concentration gradient

Diffusion is passive transport movement from high to low concentration

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27
Q

Semi Permeable Membrane

A

Some things go through it while others dont

Polar molecules can’t move through the cell membrane as easily as nonpolar molecules

Water (polar) is able to move through the cell membranes due to specific channel the membrane as for water molecules.

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28
Q

Osmosis

A

Diffusion of water

Whatever side has the most stuff dissolved in it the water molecules will follow

Cytoplasm of the cell is an aqueous solution

Water is solvent

Dissolved substances are solutes

Net diffusion of water across a membrane toward a higher solute concentration

Water will always follow the solutes

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29
Q

Osmotic Concentration

A

When 2 solutions have different osmotic concentrations

Hypertonic- higher solute concentration

Hypotonic- lower solute concentration

When two solutions have the same osmotic concentration, the solutions are isotonic

Aquaporins- holes in the cell membrane

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30
Q

Isotonic Solution

A

Equal/Even solute concentration “Same”

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31
Q

Hypertonic Solution in Animal and Plant Cells

A

Animal cells shrink and shrivel

“dehydration”

Plant cells shrink form all the walls

Seawater is a hypertonic solution

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32
Q

Hypotonic Solution in Animal and Plant Cells

A

Cell swelling

Hypotonic hydrators

Animal cells burst due to not having a cell wall

Plant cells like hypotonic solutions -> Swelling

Water rushes into the RBC

33
Q

Maintaining Osmotic Balance

A

Isosmotic regulation involves keeping cells isotonic with their environment

Marine organisms adjust internal concentration to match sea water

Terrestrial animals circulate isotonic fluid

34
Q

Carrier Proteins

A

Can help transport both ions and other solutes, such as some sugars and amino acids

If passive, requires a concentration difference across the membrane

Must bind to the molecule they transport

Transport limited by the number of transporters

35
Q

Active Carrier Proteins

A

Move something against the concentration gradient

Requires energy-ATP is used directly or indirectly to fuel active transport

Moves substances from low to high concentration (this is why you need energy)

Requires the use of highly selective carrier proteins

36
Q

Passive Carrier Proteins

A

Uses diffusion (from high concentration to low concentration gradient)

37
Q

Carrier Protein: Uniporter

A

One thing at a time in one direction

38
Q

Carrier Protein: Symporter

A

Moves two things in the same direction

39
Q

Carrier Protein: Antiporter

A

Moves two things in opposite directions

40
Q

Carrier Protein Example: Sodium-Potassium (Na+-K+) Pump

A

Active Antiporter

Direct use of ATP for active transport

Uses an antiporter to move 3 NA+ out of the cell and 2K+ into the cell
Against their concentration gradient

ATP energy is used to change the conformation of the carrier protein

Affinity of the carrier protein for either Na+ or K+ changes so the ions can be carried across the membrane (the result)

Happens for every cell in the body

41
Q

Coupled Transport

A

Transmembrane Level

No ATP is directly used

“Secondary active transport”

Importing mechanism

Na+ passively moving + its inertia allows glucose to “catch a ride”

Moving two molecules in the same direction

Symporter is an example

42
Q

Bulk Transport

A

Requires energy -> Active process

Endocytosis
WIthin a cell

Exocytosis
Outside a cell

43
Q

Endocytosis

A

Within a cell

Movement of substances into the cell

Phagosytosis- Cell takes in large particulate matter

Pinocytosis-Cell takes in only fluid and ions

44
Q

Exocytosis

A

Outside of cell

Movement of substances out of cell

Used in plants to export cell wall material

Used in animals to secrete hormones, neurotransmitters, digestive enzymes

If the membrane is too stiff/rigid= the cell is unable to move things out

if the membrane is too fluidly then holes will form

45
Q

Phagocytosis

A

Cell exiting

46
Q

Pinocytosis

A

Cell drinking usually large quantities of water

47
Q

How does increasing the amount of cholestrol in a cell membrane change the membrane?

A

Decreases fluidity

48
Q

Pinocytois would be useful for a cell that needed to…

A

Take in lots of substances dissolved in fluid outside of the cell

49
Q

The phosolipids in the cell membrane of all from a very warm environment could contain _____ saturated fats than the phospholipids in the cell membrane of cells from a very cold enviroment.

A

More

50
Q

Imagine a phospholipid bilayer all membrane that has a greater concentration of sodium ions on the outside of the cell than on the inside. What would happen if you insert a transmembrane protein that allowed only sodium ions to pass through it in either direction?

A

Sodium would move from outside the cell to the inside of the cell

51
Q

A human red blood cell, which is permeable to water, is placed into a hyptonic solution. Which way will water move?

A

Out of the cell

52
Q

Which of the following transporters would you use to pump a potassium ion against its concentration gradient?

A

Active Carrier Protein

53
Q

What type of transport would be best to move a bacterium into a eukaryotic cell?

A

Phagocytosis

54
Q

A transmembrane protein that moves two molecules or ions in the same direction is classified as…?

A

A symporter

55
Q

Active transmembrane proteins can be used to create a concentration difference between the inside of the cell and the outside of a cell. True or False

A

True

56
Q

Hypotonic hydration is a term used to describe

A

Drinking pure water

57
Q

What are the 4 components of Cellular membranes?

A
  1. Phospholipid bilayer
    Flexible matrix, barrier to permeability
  2. Transmembrane proteins
    Integral membrane proteins
  3. Interior protein
    Peripheral or interacellular membrane proteins
  4. Cell Surface markers
    Glycoproteins and glycolipids (Sugar-protein and sugar-fats)
58
Q

Bilayers are what?

A

fluid

59
Q

What holds the 2 layers together?

A

Hydrogen bonding

60
Q

Individual_____and unanchored_____can move through the membrane

A

Phospholipids

Proteins

61
Q

What are kinks?

A

“Kinks” introduced by the double bonds keep them from packing tightly

62
Q

Most membranes contain what to increase or decrease membrane fluidity, depending on temperature?

A

Most membranes also contain sterols such as cholesterol, which can either increase or decrease membrane fluidity, depending on the temperature

63
Q

What are the various functions of membrane proteins?

A 
Transporters
Enzymes
Cell-surface receptors
Cell-surface identity markers
Cell-to-cell adhesion proteins
Attachments to the cytoskeleton
64
Q

Peripheral proteins

A

attached to either surface

65
Q

Integral proteins

A

span the lipid bilayer

66
Q

Pores

A

sheets cerate opening

67
Q

The external portion of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are _____________, in order to successfully anchor them in the phospholipid bilayer.

A.highly polar
B.negatively charged
C.non-polar
D.positively charged
E.water soluble
A

C. Non-Polar

68
Q

Barrier

A

Barrier to crossing membrane is the hydrophobic interior that repels polar molecules but not nonpolar molecules

Nonpolar molecules will move until the concentration is equal on both sides

Limited permeability to small polar molecules

Very limited permeability to larger polar molecules and ions

69
Q

Facilitated Diffusion

A

Molecules that cannot cross the membrane easily may move through proteins
Move from higher to lower concentration

Channel proteins
Carrier proteins

Membrane is selectively permeable

70
Q

What type of molecules can pass directly through the plasma membrane, without the aid of a transport protein, easiest?

A.small, polar
B.large, polar
C.small, non-polar
D.large, non-polar

A

C. Small, non-polar

71
Q

Ion Channels

A

Allow the passage of ions

Gated channels – open or close in response to stimulus (chemical or electrical)

3 conditions determine direction of ion flow
Relative concentration on either side of membrane
Voltage differences across membrane
Gated channels – channel open or closed

72
Q

Osmotic pressure

A

Force needed to stop osmotic flow

Cell in a hypotonic solution gains water causing cell to swell – creates pressure

If membrane strong enough, cell reaches counterbalance of osmotic pressure driving water in
with hydrostatic pressure driving water out

Cell wall of prokaryotes, fungi, plants, protists
If membrane is not strong, may burst

Animal cells must be in isotonic environments

73
Q

As a scientist, you perform an experiment in which you create an artificial cell with a selectively permeable membrane through which only water can pass. You put a solution of glucose into the cell and then you place the cell into a beaker of water. What observations do you expect to see?

A.Water moves out of the cell.
B.Glucose moves out of the cell.
C.No net change in cell weight.
D.Water moves into the cell.
E. Glucose moves into the cell.
A

D. Water moves into the cell

74
Q

Active Transport

A

Requires energy – ATP is used directly or indirectly to fuel active transport

Moves substances from low to high concentration

Requires the use of highly selective carrier proteins

Carrier proteins used in active transport include
Uniporters – move one molecule at a time
Symporters – move two molecules in the same direction
Antiporters – move two molecules in opposite directions

These terms can also be used to describe facilitated diffusion carriers

75
Q

Sodium- Potassium (Na+ - K+) Pump

A

Direct use of ATP for active transport

Uses an antiporter to move 3 Na+ out of the cell and 2 K+ into the cell
Against their concentration gradients

ATP energy is used to change the conformation of the carrier protein

76
Q

Osmotic concentration

A

When 2 solutions have different osmotic concentrations

Hypertonic solution has a higher solute concentration

Hypotonic solution has a lower solute concentration

When two solutions have the same osmotic concentration, the solutions are isotonic

Aquaporins facilitate osmosis

77
Q

Hypotonic

A

Hypotonic: In comparing two solutions, the one with a lower solute concentration.

Water will move towards the hypertonic solution.

Hypertonic (One gets hyper when one has too much sugar):

In comparing two solutions, it is referring to the one with a higher solute concentration.

Water will move towards the hypertonic solution

78
Q

Isotonic

A

The concentration of solute is the same inside and outside of the membrane.

Net flow is “0”. There is equal exchange

79
Q

The process often thought of as “cell eating” is

A.osmosis
B.pinocytosis
C.phagocytosis
D.diffusion
E.active transport
A

C. phagocytosis

Bio 112 (18 decks)

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