Module 4: Cell Membrane Flashcards
form a major structural element in cells
biomembrane
encloses a cell, and its integrity is necessary to the life of the cell.
plasma membrane or cell membrane
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.
cell membrane
surrounded by a plasma membrane but contain no internal membrane-limited sub compartments
prokaryotic
partitioned by membranes into smaller sub compartments called organelles.
larger eukaryotic cells
form closed structures, separating the lumen on the inside from the outside and are based on a simple bilayer structure.
biomembrane
FUNCTIONS OF MEMBRANES
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
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
a. serves as permeability barriers
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
a. serves as permeability barriers
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
a. serves as permeability barriers
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
a. serves as permeability barriers
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
b. sites of specific functions
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
b. sites of specific functions
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
b. sites of specific functions
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
c. regulate the transport of solute
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
c. regulate the transport of solute
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
d. detects and transmits electrical and chemical signals
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
d. detects and transmits electrical and chemical signals
term used to describe the specific mechanisms used to transmit signals from the outer surface of cells to the cell interior
signal transduction
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
e. mediates cell-to-cell communication
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.
cadherin
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
e. mediates cell-to-cell communication
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
e. mediates cell-to-cell communication
refer to the membranes that comprises
the cell itself (plasma membrane) and membranes that comprise the organelles (eg golgi apparatus, mitochondria, nucleus).
biomembrane
Biological membrane functions
Boundary
Transport
Organization and Localization of functions
Signal Detection
Cell Communication
- 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
a. boundary
