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BIO 201 > Chapter 5 > Flashcards

Chapter 5 Flashcards

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1
Q

Phospholipid Bilayer

A

●The plasma membrane is common to all cells

●External surface lined with hydrophilic polar heads
●Cytoplasmic* surface lined with hydrophilic polar heads
●Nonpolar, hydrophobic, fatty-acid tails sandwiched in between

  • Cytoplasm is the gelatinous liquid that fills the inside of a cell. It is composed of water, salts, and various organic molecules
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2
Q

Fluid Mosaic Model

A

●Phospholipid bilayer
●Protein molecules
● Some phospholipids and proteins have carbohydrate chains attached, making glycolipids and glycoproteins
●Cholesterol affects the fluidity of the membrane

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3
Q

Protein molecules- Fluid Mosaic Model

A

●Float around like icebergs on a sea
●Membrane proteins may be peripheral or integral
●Peripheral proteins are found on the inner surface
●Integral proteins are embedded in the membrane

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4
Q

What do channel proteins allow through the membrane?

A

Channel proteins allow charged or large molecules through the membrane. For example, channel proteins allow ions like sodium, potassium, and calcium, as well as larger molecules like glucose, to pass through the membrane.

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5
Q

What is the function of a channel protein?

A

The function of a channel protein is to move molecules from one side of the membrane to the other without binding to them and without using energy.

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6
Q

What is an example of an inherited disorder in channel protein?

A

Cystic fibrosis, an inherited disorder is caused by a
faulty chloride (Cl–) channel; a thick mucus collects in
airways and in pancreatic and liver ducts.

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7
Q

Carrier Proteins

A
  • Selectively interacts with a specific molecule or ion so
    that it can cross the plasma membrane.
  • Combine with the substance to be transported
  • Assist passage of molecules through membrane
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8
Q

A suggested cause of Obesity - Carrier Protien

A

The inability of some persons to use energy for sodium- potassium (Na+–K+) transport has been suggested as the cause of their obesity

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9
Q

Cell Recognition Protein:

A

The MHC (major histocompatibility complex) glycoproteins are different for each person, so organ
transplants are difficult to achieve. Cells with foreign MHC glycoproteins are attacked by white blood
cells responsible for immunity.

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10
Q

Cell Recognition Proteins:

A
  • Glycoproteins (Glycoproteins are molecules that comprise of protein and carbohydrate chains that are involved in many physiological functions including immunity.)
  • Help the body recognize foreign substances
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11
Q

Receptor Protein: Relationship to Pygmies

A

Pygmies are short, not because they do not produce enough growth hormone, but because their plasma
membrane growth hormone receptors are faulty and cannot interact with growth hormone.

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12
Q

Receptor Proteins:

A

Is shaped in such away that a specific molecule can bind to it.

Allow a cell to respond to signals from other cells

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13
Q

Enzymatic Proteins:

A

Carry out metabolic reactions directly

Catalyzes a specific reaction. The membrane protein, adenylate cyclase, is involved in ATP metabolism.

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14
Q

What bacteria has enzymatic proteins?

A

Cholera bacteria release a toxin that interferes with the
proper functioning of adenylate cyclase; sodium (Na+) and water leave intestinal cells, and the individual may die from severe diarrhea.

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15
Q

Junction Proteins:

A

Attach adjacent cells

Tight junctions join cells so that a tissue can fulfill a function, as when a tissue pinches off the neural tube
during development. Without this cooperation between
cells, an animal embryo would have no nervous system.

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16
Q

Permeability of the Plasma Membrane

A
  • The plasma membrane is differentially (selectively) permeable
  • Allows some substances to move across the membrane Inhibits passage of other molecules
  • Passive Transport:
    No ATP requirement
    Molecules follow concentration gradient
  • Active Transport
    Requires a carrier protein
    Requires energy
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17
Q

Passage of Molecules Across the Membrane

A

Energy Not Required (aka Passive)
- Diffusion
- Facilitated Transport

Energy Required
- Active Transport
-Bulk Transport

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18
Q

Diffusion

A

Diffusion is a spontaneous process in which a substance moves from a region of high concentration to a region of low concentration, eventually eliminating the concentration difference between the two regions.

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19
Q

Simple Diffusion

A

-A solution consists of:
A solvent (liquid), and
A solute (dissolved solid)
- Diffusion
Net movement of solute molecules down a gradient
Molecules move both ways, but net high to low
- Equilibrium:
When NET movement stops
Solute concentration is uniform

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20
Q

Example of Facilitated Transportation - Gas Exchange in Lungs

A

Energy is not required to move oxygen or carbon dioxide across membranes. Instead, these gases follow pressure gradients that allow them to diffuse. The anatomy of the lung maximizes the diffusion of gases: The respiratory membrane is highly permeable to gases; the respiratory and blood capillary membranes are very thin; and there is a large surface area throughout the lungs.

21
Q

Osmosis

A

Osmosis is the process by which water molecules pass through a membrane from a region of higher water concentration to a region of lower water concentration.

The movement of water molecules through the cell membrane is caused by differences in the concentration of the solute on its two sides.

22
Q

Osmosis

A
  • Special case of diffusion
  • Focuses on solvent (water) movement rather than solute
  • Diffusion of water across a differentially (selectively) permeable membrane
  • Solute concentration on one side is high, but water concentration is low
  • Solute concentration on other side is low, but water concentration is high
  • Water can diffuse both ways across membrane but the solute can’t
    -Net movement of water is toward low water (high solute) concentration
23
Q

What is Osmotic pressure?

A

is the pressure that develops due to osmosis

The amount of water contained within the cell creates a pressure

The cell membrane regulates the osmotic pressures of intracellular and intercellular fluids.

24
Q

Types of Transport: Osmosis

A

Isotonic Solution

Hypotonic Solution

Hypertonic Solution

25
Q

Describe Isotonic Solution

A
  • When the internal solute concentration equals the external solute concentration, it is said to be isotonic.
  • No net movement of water in or out of the cells occurs.
  • Solute and water concentrations are equal on both sides of membrane
26
Q

Hypotonic Solution

A

Concentration of solute in the solution is lower than inside the cell - also known as endosmosis

Cells placed in a hypotonic solution will swell

May cause cells to break

27
Q

Hypertonic Solution

A

Concentration of solute is higher in the solution than inside the cell - as known as exosmosis

Cells placed in a hypertonic solution will shrink or
Plasmolysis an example is a plant loses its support and wilts.

28
Q

Isotonic in Animal Cells

A

In an isotonic solution, there is no net movement of water.

29
Q

Hypotonic in Animal Cells

A

In a hypotonic solution, water mainly enters the cell, which may burst (lysis is the breaking down of the membrane of a cell).

30
Q

Hypertonic in Animal Cells

A

In a hypertonic solution, water mainly leaves the cell, which shrivels (crenation - cells shrink and their forms become altered during crenation, generally with a ruffled or scalloped edge).

31
Q

Isotonic in Plant Cells

A

In an isotonic solution, there is no net movement of water.

32
Q

Hypertonic in Plant Cells

A

In a hypertonic solution, vacuoles lose water, the cytoplasm shrinks (plasmolysis), and chloroplasts
are seen in the center of the cell.

33
Q

Hyportonic in Plant Cells

A

In a hypotonic solution, vacuoles fill with water, turgor pressure (Pressure exerted by fluid in a cell that presses the cell membrane against the cell wall. Turgor is what makes living plant tissue rigid) develops, and chloroplasts are seen next to the cell wall.

34
Q

Facilitated Transport

A
  • Molecules that can’t get through membrane lipids
  • Combine with carrier proteins
  • Follow concentration gradient, moving from high
    concentration to low concentration
35
Q

Types of Transport: Carrier Proteins

A

Facilitated Transport - This is a type of passive transport (does not require metabolic energy) in which molecules that cross the cell membrane move quickly due to the presence of specific permeases* in the membrane.

Active Transport - is a kind of cellular transport in which substances like amino acids, glucose and ions are transported across cell membranes to a region that already has a high concentration of such substances.

*is basically a transmembrane pump which carries symport of lactose with proton

36
Q

Active Transport

A
  • Molecules move against concentration gradient, from low concentration to high
  • Molecules combine with carrier proteins
  • Requires energy
37
Q

The major function of the sodium-potassium pump is to:

A

a. pump Na+ into and K+ out of the cell.
b. generate the resting membrane potential.
c. maintain the concentration gradients of Na+ and K+ across the plasma membrane.
d. oppose any tendency of the cell to undergo hyperpolarization.

38
Q

The Sodium-Potassium Pump Cycle

A

It is an active cycle

  1. Carrier has a shape that allows it to take up 3 Na+.
  2. ATP is split, and phosphate group attaches to carrier.
  3. Change in shape results and causes carrier to release 3 Na+ outside the cell.
  4. Carrier has a shape that allows it to take up 2 K+
  5. Phosphate group is released from carrier.
  6. Change in shape results and causes carrier to release 2K+ inside the cell.
39
Q

Membrane-Assisted Transport

A

Macromolecules are transported into or out of the cell inside vesicles

40
Q

Macromolecules are transported into or out two ways

A

Exocytosis – Vesicles fuse with plasma membrane and secrete contents

Endocytosis – Cells engulf substances into a pouch which becomes a vesicle

41
Q

What is Phagocytosis

A

It is one type of endocytosis.

Phagocytosis is the process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome.

42
Q

What is Pinocytosis

A

pinocytosis, otherwise known as fluid endocytosis and bulk-phase pinocytosis, is a mode of endocytosis in which small molecules dissolved in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in their containment within a small vesicle inside the cell.

43
Q

What is Receptor-Mediated Endocytosis

A

– Specific form of pinocytosis using receptor proteins and a coated pit

44
Q

What are cell Junctions

A

Cell junctions are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals.

Combined with cell adhesion molecules and extracellular matrix, cell junctions help hold animal cells together.

45
Q

In vertebrates, there are three major types of cell junction:

A

-Adhesion junctions (aka anchoring junctions)
- Gap junctions (aka communicating junction)
- Tight junctions (aka obstruction junctions)

46
Q

Adhesion Junctions

A

Adhesion or anchoring-type junctions not only hold cells together but provide tissues with structural cohesion.

These junctions are most abundant in tissues that are subject to constant mechanical stress such as skin and heart.

47
Q

Gap Junctions

A

Gap junctions or communicating junctions, allow for direct chemical communication between adjacent cellular cytoplasm through diffusion without contact with the extracellular fluid.

48
Q

Tight Junctions

A

Tight junctions act as barriers that regulate the movement of water and solutes between epithelial* layers

*epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix.

BIO 201 (5 decks)

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