Lecture 6 Flashcards
(15 cards)
What is the role of the cell membrane as a barrier?
It separates a cell from its surroundings, maintains a distinct molecular composition, and prevents free mixing of molecules across the membrane.
Example: The cell membrane acts as a selective barrier, allowing only certain molecules to pass through.
How do receptor proteins in the cell membrane function in communication?
They allow cells to receive environmental signals, enabling response and adaptation to changes.
Additional information: Receptor proteins can trigger various intracellular signaling pathways.
What is the primary function of glycerophospholipids in the cell membrane?
They contribute to membrane fluidity and structure, comprising the majority of the lipid bilayer.
Example sentence: Glycerophospholipids form the basic structure of the cell membrane.
How does cholesterol impact membrane fluidity?
Cholesterol maintains fluidity by preventing freezing and maintaining membrane stability across temperature changes.
Example: Cholesterol helps regulate the fluidity of the membrane in different environmental conditions.
What types of movement do flippases, floppases, and scramblases facilitate in the membrane?
They regulate lipid movement between the inner and outer leaflets of the membrane.
Additional information: Flippases move lipids from the outer to inner leaflet, while floppases move lipids in the opposite direction.
Differentiate between integral and peripheral membrane proteins.
Integral proteins span the membrane with hydrophobic and hydrophilic regions, while peripheral proteins are temporarily associated and do not fully span the membrane.
Example: Integral proteins are embedded within the membrane structure, while peripheral proteins are attached on the surface.
Describe the function of ion channel-linked receptors.
They open or close in response to a ligand binding, allowing ions to pass through the membrane and initiating a cellular response.
Example sentence: Ion channel-linked receptors are essential for nerve signaling and muscle contraction.
What is the role of the glycocalyx in decreasing dehydration?
It regulates fluid movement across cell surfaces and maintains vascular integrity, preventing dehydration.
Additional information: The glycocalyx also plays a role in cell adhesion and immune response.
Explain how O-linked and N-linked glycosylation differ.
N-linked glycosylation starts in the ER with attachment to nitrogen of asparagine, while O-linked starts in the Golgi with attachment to the oxygen of serine or threonine.
Example: N-linked glycosylation is a co-translational modification, while O-linked glycosylation is a post-translational modification.
What is the function of endocytosis and exocytosis in membrane transport?
They are processes for transporting substances into (endocytosis) and out of (exocytosis) cells, using vesicles that fuse with the membrane.
Example sentence: Endocytosis is crucial for nutrient uptake, while exocytosis is important for secretion of cellular products.
How do glycolipids contribute to cell recognition?
They are involved in cell-cell interactions and recognition, such as in antigenic functions determining blood type.
Additional information: Glycolipids play a key role in immune response and tissue development.
What component of the membrane primarily impacts its fluidity?
Membrane lipids, including unsaturated fatty acids and cholesterol, are crucial in determining membrane fluidity.
Example: Changes in lipid composition can significantly alter membrane fluidity.
Discuss the significance of gap junctions in cell communication.
Gap junctions allow direct communication between cells by enabling passage of ions and small molecules.
Example: Gap junctions play a vital role in coordinating cellular activities in tissues like the heart and brain.
What function do tight junctions serve in the cell membrane?
They provide adhesion and create a barrier that controls the movement of molecules between epithelial cells.
Example sentence: Tight junctions help maintain tissue integrity by preventing leakage between cells.
How do sphingolipids contribute to membrane structure?
Sphingolipids, such as glycosphingolipids, include sphingosine and form ceramide, contributing to membrane stability and functionality.
Additional information: Sphingolipids are important components of lipid rafts in the membrane.
