Module 4: Cell Membrane

Question 1

form a major structural element in cells

Answer 1

biomembrane

Question 2

encloses a cell, and its integrity is necessary to the life of the cell.

Answer 2

plasma membrane or cell membrane

Question 3

Prokaryotic and eukaryotic cells are surrounded by this structure which defines its boundaries and gives the essential differences between the cytoplasm and the extracellular environment.

Answer 3

cell membrane

Question 4

surrounded by a plasma membrane but contain no internal membrane-limited sub compartments

Answer 4

prokaryotic

Question 5

partitioned by membranes into smaller sub compartments called organelles.

Answer 5

larger eukaryotic cells

Question 6

form closed structures, separating the lumen on the inside from the outside and are based on a simple bilayer structure.

Answer 6

biomembrane

Question 7

FUNCTIONS OF MEMBRANES

Answer 7

Serves as Permeability barriers
Sites of specific functions
Regulates the transport of solute
Detects and transmits electrical and chemical signals
Mediates cell-to cell communication

Question 8

boundaries of the cell and its compartments must be
defined – to keep desirable substances in and the undesirable
substances out

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 8

a. serves as permeability barriers

Question 9

The interior, lipid bilayer of the membrane (hydrophobic) is an effective _______ that restricts the passage of most polar, hydrophilic molecules and ions.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 9

a. serves as permeability barriers

Question 10

Also, to maintain
concentration of solution in its cytosol that differ from those
of extracellular fluid (ECF) and in each organelle.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 10

a. serves as permeability barriers

Question 11

This _______ function allows the cell to maintain concentrations of solutes in its cytosol that differ from those in the extracellular fluid and in each of the intracellular membrane-enclosed compartments.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 11

a. serves as permeability barriers

Question 12

An example for such cell functions are cell respiration and the protein processing in the endoplasmic reticulum because molecules and structures responsible for those functions are either embedded in or localized on membranes.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 12

b. sites of specific functions

Question 13

Specific membranes are known and identified based on the particular enzymes, transport proteins, receptors, and other
molecules associated with it. Certain enzymes become markers to identify particular membranes during isolation of organelles.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 13

b. sites of specific functions

Question 14

Ex. Glucose-6-phosphatase is a membrane-
bound enzyme in the ER. If present in a preparation of mitochondria it means contamination with ER membranes.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 14

b. sites of specific functions

Question 15

Cells may have specific transporters for glucose, amino acids or other nutrients. Na+ & K+ ions are transported by specific ion channel proteins in the cell membranes of neurons. Nerve cells transmit electrical signals as Na+ and K+ ions are transported across the plasma membrane of neurons by specific ion channel proteins.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 15

c. regulate the transport of solute

Question 16

Transport proteins
in muscle cells move calcium ions across membranes to assist
in muscle contraction.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 16

c. regulate the transport of solute

Question 17

Membranes contain the protein molecules that act as receptors to detect external signals.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 17

d. detects and transmits electrical and chemical signals

Question 18

The binding of specific signal molecules to their receptor triggers specific chemical events on the inner membrane that lead to changes in cell function.

Example, muscle and liver cell membranes contain insulin receptors and can therefore respond to this hormone, which helps cells take in glucose. WBCs have specific receptors that recognize chemical signals from bacteria and initiate a cellular defense response.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 18

d. detects and transmits electrical and chemical signals

Question 19

term used to describe the specific mechanisms used to transmit signals from the outer surface of cells to the cell interior

Answer 19

signal transduction

Question 20

Multicellular organisms have a variety of ways to adhere or be in contact with other cells.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 20

e. mediates cell-to-cell communication

Question 21

are membrane proteins that provide specific cell-to-cell contact, a process that is critical during embryonic development in animal. The extracellular sequences of amino acids bind calcium ions and stimulate adhesion between similar cells in a tissue.

Answer 21

cadherin

Question 22

Other membrane proteins in animal tissues form adhesive junctions, which hold cells together, and tight junctions, which form seals that block the passage of fluids between cells. Membrane proteins such as ankyrin can also be points of attachment to the cell cytoskeleton, lending rigidity to tissues.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 22

e. mediates cell-to-cell communication

Question 23

The gap junctions in animal cells and
plasmodesmata in plant cells provide direct cytoplasmic connections that allow the exchange of at least some cellular components.

a. serves as permeability barriers
b. sites of specific functions
c. regulate the transport of solute
d. detects and transmits electrical and chemical signals
e. mediates cell-to-cell communication

Answer 23

e. mediates cell-to-cell communication

Question 24

refer to the membranes that comprises
the cell itself (plasma membrane) and membranes that comprise the organelles (eg golgi apparatus, mitochondria, nucleus).

Answer 24

biomembrane

Question 25

Biological membrane functions

Answer 25

Boundary
Transport
Organization and Localization of functions
Signal Detection
Cell Communication

Question 26

• Physical barrier that demarcates the internal components
  against extracellular components
• Semi-permeability

a. boundary
b. transport
c. organization and localization of functions
d. signal detection
e. cell communication

Answer 26

a. boundary