Module 3: Structures Flashcards
It contains the Phospholipid, Membrane proteins, Carbohydrate chain, cholesterol, membrane proteins.
Cell Membrane
Also known as cellular
membrane or plasma
membrane
Biological Membrane
The cell membrane______________ the
cell from the outside
environment.
Separates and protect
______________ from the cell membrane that
surrounds a cell.
Outermost envelope
Two layers of
phospholipids
arranged backto-
back which
covers the cell.
Lipid Bilayer
Cell takes in macromolecules by
forming vesicles from the plasma
membrane
Endocytosis
Transport vesicles migrate to the
membrane, fuse with it, and
release their contents outside the
cell
Exocytosis
Requires the input of energy from the cell.
Active Transport
Uses ATP and protein pumps to transport
molecules against the concentration
gradient (low to high concentrations).
Active Transport
Sodium-potassium pump
* Cell to cell communication (synapses)
* Action potentials
* Nervous system functions
Active Transport
Channel proteins have a hydrophilic
channel that certain molecules or ions can use as a tunnel.
Passive Transport
Channel proteins called aquaporins
facilitate the passage of water
Passive Transport
Carrier proteins bind to molecules and
change shape to shuttle them across the membrane.
Passive Transport
the control of
solute concentrations and water
balance, is a necessary adaptation for
life in such environments.
Osmoregulation
A protist, which is
hypertonic to its pond water
environment, has a contractile
vacuole that acts as a pump.
Paramecium,
is the ability of a surrounding solution to cause a cell to gain or lose water
Tonicity
Solute concentration is the same as that inside the cell; no net
water movement across the plasma membrane
Isotonic solution
Solute concentration (high to low) is greater than that inside
the cell; cell loses water
Hypertonic solution
Solute concentration is less than that inside the cell; cell
gains water
Hypotonic solution
Solute that moves from high to low concentrations
Diffusion
Solvent moves from low to high concentrations
Osmosis
Occurs without the input of cellular
energy. High concentration to low concentration
Passive Transport
- Simple diffusion (i.e. oxygen).
- Facilitated diffusion
* Channel mediated
* Carrier Mediated
Passive Transport
Transport of biomolecules does what? (Three answers)
- Selectively permeable
- Regulate what enters and
exits the cell. - Facilitating the transport
of materials needed for
cell activities.
Physically
separates the
intracellular
components of
the cells from
the extracellular
environment.
Protection of cells
Bound either to proteins
(forming glycoproteins) or to
lipids (forming glycolipids).
Plays a key role in cell
recognition and
protection.
Found on the outside
surface of cells.
Carbohydrates
- Maintains the structural
integrity of the cell. - Regulates the fluidity of cell
membranes.
Cholesterol
- Extrinsic membrane protein
- Loosely associated with the
membrane surface. - Either on the extracellular or
cytoplasmic surface. - Connected to the polar head
of the lipid bilayer. - Hydrophilic in nature.
Peripheral Membrane Proteins
- Type of integral membrane protein.
- The protein itself is not in contact
with the membrane. - Anchored on the cell membrane
through covalent binding to a lipid
molecules. - i.e. glycosyl-phosphatidylinositol
or GPI anchored proteins.
Lipid-Anchored Membrane Proteins
- Made by Singer and Nicolson in
1972 - No consistent pattern or
arrangement; just like a mosaic - Cell membrane has proteins that are
partially embedded
Fluid Mosaic Model
- Forms basic structure of
membrane - Acts as barrier
Phospholipid Bilayer
- Manage passage of required
molecules - Facilitate communication
within cell’s environment
Membrane Proteins
3 adaptations of cell membrane
Hot environment, Cold environment, Extremely salty environments
(Cell membrane - cellular communication)
- Neurotransmitter-mediated
signaling
- Allow neurons to transmit
signals through chemicals
Chemical Synapses
(Cell membrane - cellular communication)
Direct electrical coupling
- Allow neurons to transmit
signals through electricity
Electrical Synapses
- Intrinsic membrane protein
- Permanently embedded in
membrane - Connected to nonpolar head of lipid
bilayer - Hydrophobic
- ie. transmembrane and transport
proteins
Integral Membrane Protein
Where membranes of
neighboring cells are pressed
together, preventing leakage of
extracellular fluid.
tight junctions
(anchoring
junctions) Junction that fasten cells together into
strong sheets
Desmosomes
(communicating
junctions) Junctions that provide cytoplasmic
channels between adjacent cells
Gap junctions
Neighboring cells in tissues,
organs, or organ systems often
adhere, interact, and communicate
through direct physical contact
Cell Junctions
ECM is made up of _____ such as collagen, proteoglycans,
and fibronectin
glycoproteins
ECM proteins bind to _______ in the plasma membrane called
integrins
receptor proteins
Microtubules control the beating of _____ and ______ microtubule-containing extensions that
project from some cells
flagella and cilia
are the thickest of the 3 components of the cytoskeleton
Microtubules
(actin filaments) are the thinnest components
Microfilaments
are fibers with diameters in a middle range
Intermediate filaments
encloses the nucleus, separating it from the cytoplasm
Nuclear envelope
is a double
membrane; each membrane
consists of a lipid bilayer
Nuclear membrane
is located within
the nucleus and is the site of
ribosomal RNA (rRNA) synthesis
nucleolus
