The Cell Membrane Structure Flashcards
Gateway of the cell that acts as a boundary, controls what enters and leaves, regulates chemical composition, and maintains homeostasis of the cells
Cell Membrane
Most commonly studied organism for cell membrane
Erythrocytes
Flexible and allows a unicellular organisms to perform locomotion
Cell Membrane
A model that suggests that the plasma membrane is made of two layers of globular proteins with phospholipid inside to make a layer and then join two layers together to make a channel for molecules to pass
Sandwich Model
Who were the proponents of the Sandwich Model
Danielli and Davson
Model that suggests the plasma membrane has an outer layer of glycoprotein coat with phospholipid bilayer inside. Proposed by Robertson
Unit membrane model
Model that suggest the phospholipid bilayer are composed with proteins partially or fully imbedded. The basic paradigm of biological membrane structure proposed by Singer and Nicolson
Fluid-Mosaic Model
The lipids in a membrane are organized into a __________________________
Liquid crystalline lattice
The transition temperature of the lipid membrane
-20 degrees celsius to 60 degrees celsius
How many types of protein are present in the cell membrane?
50 different types of protein
Trait of the lipid molecules to having a hydrophilic and a hydrophobic end
Amphipathic or Amphiphilic
Process of rapidly freezing membrane followed by a fractionation using a knife
Freeze-Fracture
Why is the plasma membrane composed of two layers of lipids?
To repel the water that constantly surrounds the cell. To much water can cause the cell to burst
Describes that the plasma membrane has consistency of olive oil at body temperature due to unsaturated phospholipids.
Fluid
Characteristic of the plasma membrane where proteins form a collage that differs on either side of membrane and from cell to cell (greater than 50 types of proteins)
Mosaic
State of hydrocarbons when exposed to low temperatures:
Gel phase
Hydrocarbon phase at high temperatures
Fluid phase
Formation of _________ is energetically favorable
Sphere
______ a harsh ionic detergent, and ________, a gentler non-ionic detergent commonly used as solubilizing agents
SDS, Triton X100
Types of phospholipid membrane movement
- Lateral Diffusion
- Flexion
- Rotation
- Flip-flop(rare)
It affects the fluidity of the plasma membrane
Cholesterol
Found in plants and serves the same purpose as cholesterol in the plasma membrane
Sterol
How does cholesterol affect fluidity at body temperature?
Lessens fluidity
Restrains the movement of phospholipids, also reducing permeability
Cholesterol maintains fluidity by not allowing phospholipids to pack close together during
Colder temperatures
__________ of the cholesterol makes the plasma membrane more rigid, less permeable, and resistant to low temperature crystalization
Planar rings
Major membrane component in animal cells. Not found on plant cells. Sterols function the same.
Cholesterol
Solid state of the plasma membrane
Paracrystalline state
Classification of Membrane Proteins
- Peripheral Membrane Proteins
- Integral Membrane Proteins
- Transmembrane Proteins
Types of Membrane Proteins
- Channel Protein
- Carrier Protein
- Cell Recognition Protein
- Receptor Protein
- Enzymatic Protein
Channel and Carrier proteins belong to this classification of membrane proteins
Transport Proteins
Protein for insoluble molecules and ions to pass through freely
Channel Proteins
Binds to a substance/solute and carry it across the membranes, conforms to the shape of the substance in process
Carrier Proteins
Binds to chemical messengers which sends a signal to the cell, causing cellular reaction
Receptor Protein
Carries out enzymatic reactions at the membrane when a substrate binds to it
Enzymatic Proteins
Serves as ID tags of the cell, made from glycoproteins
Cell recognition proteins
Maintains cell shape and stabilize by attaching to the cytoskeleton or the extracellular matrix
Attachment Proteins
Space between the cells composed and filled with proteins and carbohydrates secreted by the cells in return supports the cells in a tissue
Extracellular Matrix
Binds the cells together, two types: Tight and Gap junctions
Intercellular Junction Proteins
Type of cell junction where transmembrane proteins of opposite cells attach in a zipper like fashion
No leakage
Tight junctions
Bars the movement of dissolved materials
Cytoplasmic plaques of two cells bind with the aid of intermediate filaments of keratin
Allows for stretching
Ex. Bladder, Stomach, Heart
Desmosomes
Channel of opposing cells join together creating small channels for ions, sugars, amino acids, and other small molecules to pass
Allows direct communication between cells
Gap Junctions
A type of gap junction present on plant cells
Plasmodesmata
Establishes the rate of Membrane Component Movement
Fluorescence Recovery After Photobleaching (FRAP)
The lattice becomes a _________ at transition temperature
Frozen crystalline gel
