Biomembrane And Cell Architecture Flashcards
What are the three classes of lipids found in biomembranes?
- Phosphoglycerides
- Sphingolipids
- Cholesterol
These lipids play crucial roles in the structure and function of biomembranes.
What is the structure of a typical phosphoglyceride molecule?
Consists of a hydrophobic tail with two fatty acyl chains esterified to glycerol phosphate and a polar head group attached to the phosphate group.
Fatty acyl chains may differ in carbon number and saturation.
What are the two important properties of the lipid bilayer?
1) The hydrophobic core is an impermeable barrier to water-soluble solutes.
2) The stability of the bilayer is maintained by hydrophobic and van der Waals interactions.
These properties allow the bilayer to retain its architecture despite environmental changes.
What are the three ways proteins interact with membranes?
- Integral membrane proteins
- Lipid-anchored membrane proteins
- Peripheral membrane proteins
Each type has a distinct mechanism of interaction with the membrane.
What is a lipid raft?
Microdomains where cholesterol and sphingolipids cluster with specific proteins, forming detergent-resistant membranes.
Lipid rafts play a role in signaling and membrane organization.
What technique is used to quantify lateral movements of specific plasma-membrane proteins and lipids?
Fluorescence recovery after photobleaching (FRAP).
This technique allows observation of membrane dynamics.
What does net flux indicate?
The movement of a substance into the cell (influx) and out of the cell (efflux) is not balanced.
This means that one process exceeds the other.
Fill in the blank: Simple diffusion through the lipid bilayer is a type of _______.
passive transport
Passive transport does not require energy.
What is the function of mitochondria?
Generate ATP by oxidation of glucose and fatty acids.
Mitochondria are known as the powerhouses of the cell.
What is the role of lysosomes?
Degrade material internalized by the cell and worn-out cellular membranes and organelles.
Lysosomes contain enzymes that facilitate this degradation.
What is the function of the nuclear envelope?
Encloses the contents of the nucleus; the outer membrane is continuous with the rough ER.
This structure protects genetic material and regulates transport.
What is synthesized in the nucleolus?
Most of the cell’s rRNA.
The nucleolus plays a key role in ribosome biogenesis.
What does the smooth endoplasmic reticulum (ER) do?
Synthesizes lipids and detoxifies certain hydrophobic compounds.
The smooth ER is involved in lipid metabolism.
What is the primary function of rough endoplasmic reticulum (ER)?
Synthesis, processing, and sorting of secreted proteins, lysosomal proteins, and certain membrane proteins.
The rough ER is studded with ribosomes, which are sites of protein synthesis.
What is the role of the Golgi complex?
Processes and sorts secreted proteins, lysosomal proteins, and membrane proteins synthesized on the rough ER.
The Golgi apparatus is key for modifying proteins before they are sent to their destinations.
What do secretory vesicles do?
Store secreted proteins and fuse with the plasma membrane to release their contents.
This process is crucial for exocytosis.
What is the function of peroxisomes?
Detoxify various molecules and break down fatty acids to produce acetyl groups for biosynthesis.
Peroxisomes contain enzymes that facilitate these reactions.
What is the function of cytoskeletal fibers?
Form networks and bundles that support cellular membranes, help organize organelles, and participate in cell movement.
The cytoskeleton is essential for maintaining cell shape and facilitating intracellular transport.
What do microvilli do?
Increase surface area for absorption of nutrients from the surrounding medium.
Microvilli are especially abundant in epithelial cells.
What is the primary composition of the cell wall?
Composed largely of cellulose.
The cell wall provides structural support and protection against mechanical stress.
What is the role of vacuoles?
Store water, ions, and nutrients, degrade macromolecules, and function in cell elongation during growth.
Vacuoles are vital for maintaining turgor pressure in plant cells.
What is the function of chloroplasts?
Carry out photosynthesis and are surrounded by a double membrane containing a network of internal membrane-bounded sacs.
Chloroplasts are found in plant cells and some algae.
Can you describe the structure of phospholipids?
A hydrophobic tail with two fatty acyl chains and a polar head group attached to glycerol phosphate.
This unique structure is critical for forming lipid bilayers.
What are the two types of transport across cell membranes?
- Passive transport
- Active transport
Passive transport occurs without energy, while active transport requires energy input.
