Quiz 1 Flashcards
What are other names for a plasma membrane?
Plasmalemma or cell membrane
Major components of a cell (3)
Plasma membrane (outer) , cytoplasm, nucleus
Functions of plasma membrane (6)
- Envelope of the cell
- Perform as a semipermeable membrane
- Place for membrane receptors
- Signal transduction into intracellular environment
- Cell to cell integration
- Maintain electrical gradient between intra & extracellular (capacitance)
Components of a plasma membrane
Phospholipids,
cholesterol,
proteins,
oligosaccharide chains (linked to phospholipids and proteins)
What makes up the phospholipid-bilayer structure?
- P-Face
- E-Face
The inner layer that faces the cytoplasm in a phospholipid-bilayer structure
P-Face
The Outer layer that faces the extracellular compartment in a phospholipid-bilayer structure
E-face
Nonpolar fatty acid chains, can be _________ or _________
- Saturated; Straight
- Unsaturated; Kinked
Structural components of a phospholipid (2)
- Polar head group
- Nonpolar (long chain) fatty acid chains
What kind of fatty acid allows the phospholipid structure to be straight?
Saturated
What kind of fatty acid allows the phospholipid structure to be bent?
Unsaturated
Membrane __________ is present in about the same amount as phospholipid?
Cholesterol
Phospholipids are most stable when organized into a double layer with the _______ fatty acid chains located in a middle region away from water and the _________ polar head groups contacting the water?
Hydrophobic, hydrophilic
Phospholipids are _________, consisting of two _______ long-chain fatty acid’s liked to a charged _________ head that bears a phosphate group.
Amphipathic, non-polar, polar
The polar hydrophobic head of a phospholipid gets attracted to water on the __________, turn and that chain will automatically face __________.
Outside, inside
Fluidity is crucial for the purpose of: (4)
-Exocytosis, endocytosis, membrane trafficking and membrane biogenesis
Fluidity increases with:
- Increased temperature
- Increased number of unsaturated bonds of the fatty acyl tails
Fluidity decreases with:
Decrease in temperature
Function of Cholesterol in the plasma membrane
-Acts as a fluidity buffer with changes in temperature
Function of Cholesterol in the plasma membrane (Depending on temperature)
- Cold temperatures: prevents the membrane from becoming rigid
- Hot temperatures: Acts as an interfering molecule and lowers fluidity
Membrane Proteins constitute around ____% of plasma membrane
50
Types of Integral Protein
Transmembrane and multi pass proteins
___________ proteins are firmly embedded in the lipid layers; those that completely span the bilayer are called _________ proteins
Integral, transmembrane
Protein to lipid ratio in a plasma membrane is more or less _______
1:1
Multipass proteins can either move _______, or held static in place by part of the cytoskeleton
Laterally
List the 6 integral protein categories (6)
*Know These
Pumps, Channels, Receptors, Linkers, Enzymes, Structural proteins
____________ transport certain ions like Na+, amino acids and sugars. (Sodium potassium)
Pumps
_____________ allow for passive diffusion of small ions, molecules and water. (Aquaporin)
Channels
_________________ allow the ligands to bind to such as hormones, antibodies, coated vesicle endocytosis
Receptor Proteins
_____________ anchor the intracellular cytoskeleton to the extracellular matrix
Linker proteins
Example of Enzymes for Integral Proteins:
__________ for ion pumping
ATPases
Function of Structural Proteins
Forming junction with neighboring cells
What does Spectrin do?
Stabilizes cell membranes or erythrocytes
Mutations in spectrin causes hereditary defects of the erythrocyte such as: (2)
*Know these
Hereditary elliptocytosis, hereditary spherocytosis
Oligosaccharide chains constitute the _____________
Glycocalyx
What are glycolipids?
Phospholipids and membrane proteins that have the oligosaccharide chains attached
Types of transport across the plasma membrane (3)
-Passive, active, vesicular
What is passive transport?
Transport where no energy is requires and materials move from higher to lower concentrations
Types of passive transport
- Simple diffusion
- Facilitated Diffusion: Channel, carrier/pump
What are some characteristics of simple diffusion?
-lipophilic, diffuse easily, exchange oxygen and CO2 though the lung blood air barrier
What is aquaporin?
A protein channel that allows water to come in
What is active transport?
Transport where energy (ATP) is required to transport molecules against electrochemical gradient via carrier protein
Forms of active transport
-Primary active transport, secondary active transport
Primary Active Transport uses __________
ATP
Forms of secondary active transport
- Symporter (Same directions)
- Antiporter (Opposite directions)
How does secondary active transport work?
Harnessing energy while moving substances up the concentration gradient while pushing Na down the gradient
Forms of Endocytosis (Vesicular Transport)
Phagocytosis, pinocytosis, receptor mediated endocytosis
Definition/Process of Phagocytosis
“Cell Eating”
-Bacteria/Dead cells are engulfed and those materials are internalized and broken down (cytoplasmic vacuole/phagosome)
What blood-derived cells are specialized for phagocytosis?
Macrophages and neutrophils
Definition/Process of Pinocytosis
- “Cell Drinking”
- Involves smaller invaginations of the cell membrane which fuse and entrap extracellular fluid (looking like fluid)
What is the difference between phagocytosis and receptor mediated endocytosis
- RME: Involves receptors that will bind to a specific molecule and only take that in
- Phagocytosis: Uses cells like macrophages/neutrophil to keep area free of debris
What is an example of receptor mediated endocytosis?
Developing RBC’s in bone marrow (RBCs need Iron)
What is exocytosis?
Movement of large molecules from the cell by vesicular transport
-Move from P Face to E Face
What do secretory vesicles/secretory granules contain
Enzymes accumulated in the apical portion of cells that are ready to be released into lumen
What is membrane trafficking?
Process of membrane movement and recycling through the process of endocytosis and exocytosis
What are cells characteristically involved in endocytosis/absorption in the GI tract?
Simple epithelia
What are cells characteristically involved in exocytosis/secretion?
Glandular epithelium
What are types of glandular epithelium? (3)
Serous gland, mucus gland and demilune
What do microvilli do?
Increase surface area
What is the purpose of the serous gland?
Secreting mainly proteins and enzymes
What is the purpose of the mucus gland?
Secreting mucous
What is the purpose of the demilune?
Secretes both serous and mucous products
Cells communicate with one another to: (3)
- Regulate tissue and organ development
- To control their growth and division
- To coordinate their functions
Types of cell signalling (5)
Endocrine, paracrine, synaptic, autocrine, juxtacrine
In ____________ signaling, the signal molecules (hormones) are carried in the blood from their sources to target cells throughout the body
Endocrine
In_________ signaling, the chemical ligand diffuses in extracellular fluid but is rapidly metabolized so that its effect is only local on target cells near its source.
Paracrine
In_________signaling, a special kind of paracrine interaction, neurotransmitters act on adjacent cells through special contact areas called____________
Synaptic, synapses