In-Class Lecture 2: Membrane structure and function, Jihan notes Flashcards
What does a barrier to diffuse mean in terms of the energy demand requirement on a cell?
It decreases the energy demand, but not having to let everything in and processing everything
In the cell, where are the processes for handling glucose located?
In the cytosol
In the cell, where are the enzymes for the TCA cycle located?
Mitochondrial matrix
Where does translation occur in the cell?
In the cytosol
What are two key features of a membrane enhancing its chances of survival?
- They are flexible
2. They are self-healing
What 5 processes are dependent on a cell’s ability to add or remove membrane?
- Cell growth
- Synaptic vesicle recycling
- Neurotransmitter and hormone release
- Nerve regeneration
- Insulin regulation of glucose transporters
How does exocytosis impact the total cell membrane surface area?
It allows for its expansion
Exocytosis, in conjunction with endocytosis, leads to the ability to regulate ___ and ___ sensitivity in target cells (membrane remodeling)
Transport and signal
Exocytosis is the process by which what type of signals can be stored in a cell and released when needed?
Hydrophilic signals (like polypeptide hormones and most neurotransmitters)
What are two appropriate signals that initiate exocytosis?
- Binding of ligand to cell surface receptors
2. Transient depolarization (such as with an action potential in a neuron)
What three steps are involved in the cascade of exocytosis with the appropriate signaling?
- Increase in intracellular calcium
- Interactions of SNARE and SNAP proteins
- ATP hydrolysis
What are three functions of endocytosis?
- To remove proteins from the cell membrane (glucose transporters)
- Form intracellular vesicles (synaptic vesicle recycling)
- Incorporate particulate matter from the ECF (example of phagocytosis)
What diseases are implicated in the process of endocytosis?
Hepatitis, polio, AIDS, iron toxicity
In the process of endocytosis, the inner leaflet of an endocytotic vesicle is made of the ___ ____ of the cell membrane.
outer leaflet
For receptor-mediated endocytosis, what type of protein molecules occur where the membrane invagination will take place?
Clathrin
Coated vesicles, from the process of endocytosis, generally fuse with primary lysosomes, making secondary lysosomes. What are the enzymes within responsible for? What molecules are produced by the lysosomes, that are used by the cell?
The lysosomal enzymes digest the contents within the coated vesicle. This frees up amino acids, simple sugars, and nucleotides to be used by the cell.
What three factors are necessary to provoke endocytosis?
- Energy (often from ATP hydrolysis)
- Calcium (keeps the ligand bound)
- Contractile elements of the microfibrils in the cell (to pinch off the vesicle)
What is a hydration sphere, as it relates to the lipid bilayer of a cell?
The hydration sphere is a coating of water molecules around an ion or molecules; they stabilize hydrophilic compounds in solution. When this layer is shed, the compound goes to a higher energy state, but it is done to cross the lipid bilayer to the area of hydrophobicity.
What is a glucose that is newly acquired by a cell phosphorylated by? What is formed?
Hexokinase, forming glucose-6-phosphate.
How does phosphorylating a glucose molecule keep it inside the cell? 2 parts
- The phosphate makes glucose-6-phosphate even more hydrophilic than glucose
- G6P is not a substrate for the GLUT transporters (while regular glucose is), leading to a reduced likelihood that the glucose will be transported out of the cell.
