3. Cell Membrane and Structure Composition Flashcards
Amino acid
- molecules that combine to form proteins
- Amino acids and proteins are the building blocks of life
Charged/uncharged molecules meaning
any particle that contains more electrons than protons is said to be negatively charged
Hydrogen Bond
interaction involving a hydrogen atom located between a pair of other atoms having a high affinity for electrons
Lipid
any of various organic compounds that are insoluble in water
Polar /unpolar molecules
Polar: Positive and Negative ends on some molecules
Partial negative charge
the more electronegative atom is the one with the partial negative charge
Partial positive charge
less electron-dense region
Plasma Membrane
- a thin fatty film studded with proteins and coated with carbohydrates
- A living cell is a self-reproducing system of molecules held inside a container
Functions of Plasma Membrane
- cell communication
-import and export of molecules
-cell growth
-motility
Amphipathic
- Molecules with both hydrophilic and hydrophobic parts
- All membrane lipids
Phospholipids
- hydrophilic heads face water on both surfaces of the bilayer
- hydrophobic tails are all shielded from the water and lie next to one another in the interior
How the hydrophobic and hydrophilic regions of phospholipids are involved in
membrane formation
Structure:
- Head: Hydrophilic, polar, attracted to water.
- Tails: Hydrophobic, nonpolar, repelled by water.
Membrane Bilayer:
-Spontaneous arrangement in aqueous environment.
- Forms a lipid bilayer, the basis of cell membranes.
Hydrophobic Tails:
-Cluster together to create a nonpolar interior.
Impermeable barrier to water-soluble molecules.
Hydrophilic Heads:
- Face outward, interact with watery surroundings.
- Maintain compatibility with both inside and outside of the cell.
Amphipathic Nature:
- Self-assemble into bilayer spontaneously.
- Driven by the need to minimize exposure of hydrophobic tails to water.
Membrane Fluidity:
- Influenced by phospholipid composition.
- Unsaturated fatty acids increase fluidity, saturated fatty acids lead to rigidity.
Protein Integration:
- Membrane proteins have hydrophobic regions.
- Embedded or associated with the lipid bilayer.
How membrane fluidity can be regulated by the cell
Lipid Composition:
- Adjust phospholipid types.
- More unsaturated fats increase fluidity.
Cholesterol:
- Acts as a fluidity buffer.
- Maintains optimal conditions.
Temperature Sensing:
- Adjusts lipid composition with temperature changes.
Protein Influence:
- Membrane proteins impact fluidity.
- Affect lipid movement and arrangement.
Dynamic Membrane:
- Regulates lipid movement within the membrane.
Desaturation Enzymes:
- Produce enzymes for unsaturated fatty acids.
- Enhances fluidity as needed.
Adaptation:
- Cells alter lipid composition based on environmental changes.
How new membrane are synthesized and matured
Lipid Synthesis:
- Cells produce lipids, especially phospholipids, in the endoplasmic reticulum (ER).
Phospholipid Assembly:
- Newly synthesized lipids are assembled into bilayers within the ER.
Vesicle Formation:
- Portions of the ER membrane form vesicles, transporting lipids.
Golgi Processing:
- Golgi apparatus modifies lipids and processes proteins.
Protein Integration:
- Membrane proteins are synthesized and inserted into the ER membrane.
Vesicle Budding:
- Vesicles containing modified lipids and proteins bud off from the Golgi.
Transport to Cell Membrane:
- Vesicles fuse with the cell membrane, incorporating new components.
Membrane Maturation:
Integrated lipids and proteins undergo modifications for maturation.
Lateral Movement:
- Components move laterally within the membrane, contributing to fluidity.
Endocytosis and Exocytosis:
- Membrane components are recycled or replaced through internalization and release.
Differentiate between integral and peripheral proteins
Inegral proteins:
- exposed to aqueous enviornemnt on both sides of membrane
- used to transport molecules across membranes
- extend through the lipid bilayer (transmembrane,
associated with the lipid monolayer, or lipid-linked
Peripheral proteins:
- located on surface of membrane
- interact with integral membrane proteins or phospholipids
How the movement of membrane components is restricted
- Lipid composition
- Cholestoral content
- Protein interactions
- Cytoskeleton Attachment
Compare and contrast the three types of cell junctions found in animals
- Tight Junctions
- Desmosomes
- Gap Junctions
Tight Junctions
Function:
-Forms a tight seal between adjacent cells.
- Prevents leakage of extracellular fluids and solutes between cells.
Structure:
- Proteins from adjacent cells interact to create a continuous barrier.
- Tight junctions are found near the apical surface of epithelial cells.
Location:
- Abundant in tissues where a strong barrier is essential, such as epithelial linings of the digestive tract.
Desmosomes
Function:
- Provides mechanical strength and resilience to tissues.
- Anchors cells together and distributes tension or stress.
Structure:
- Connects the cytoskeletons of adjacent cells.
- Consists of cadherin proteins and linker proteins forming a dense structure.
Location:
- Common in tissues subjected to mechanical stress, such as skin and heart muscle.
Gap Junctions
Function:
- Facilitates direct communication and exchange of small molecules between adjacent cells.
- Allows the passage of ions, metabolites, and signaling molecules.
Structure:
- Consists of connexin proteins forming channels (connexons) that align between adjacent cells.
Location:
- Found in various tissues where coordinated activity or signaling between cells is crucial, such as cardiac muscle.
Do on paper
- Predict how removal of any components of the cell membrane affect its properties and
function
-Design investigations to analyze the function of proteins and carbohydrates in cell
adhesion and cell recognition
