Membranes Flashcards
Which is polar, the hydrophilic head or hydrophobic tail?
hydrophilic head
Which is negatively charged, the hydrophilic head or hydrophobic tail?
hydrophilic head
What is the charge of the hydrophobic tail?
No charge
What does cholesterol contribute to?
the fluidity and stability of the membrane.
stiffens membrane
Do peripheral proteins penetrate the membrane?
No
What do the Glycoproteins and glycolipids together form?
glycocalyx
Describe the 3 important functions of the lipid bilayer.
It forms the basic structure of the membrane.
Its hydrophobic interior serves as a barrier
The cell can maintain differences in solute composition and concentrations inside/outside the cell
It is responsible for the fluidity of the membrane
Enables the cell to change shape (e.g. RBC or a muscle cell)
What type of proteins form water-filled highly-selective ion channels?
transmembrane
What is an example of a disease where there are genetic mutations in channels?
cystic fibrosis
What carrier is expressed by thyroid gland cells?
iodine
Where are docking marker receptors located and what do they do?
Located on the inner membrane surface
Interact with secretory vesicles leading to exocytosis of the vesicle contents
What is an example of a membrane bound enzyme which can be located on either membrane surface?
protein kinase C
What are caherins and integrins?
Cell adhesion molecules
What do cadherins do?
helps hold cells within tissues together
What do integrins do?
span the plasma membrane acting as a link between extra- and intra-cellular environments
What serve as self-identify markers that enable cells to identify and interact with one another?
membrane carbohydrate
What are different cell markers important in?
cell-to-cell interactions, especially during embryonic development
When are there abnormal surface markers?
cancer cell growth
What are desmosomes?
Adhering junctions that anchor cells together, especially in tissues subject to stretching. (e.g. skin, heart, uterus)
What are tight junctions?
Join the lateral edges of epithelial cells near their lumenal (apical) membranes. (tight or leaky)
What are gap junctions?
‘Communicating’ junctions that allow the movement of charge carrying ions and small molecules between two adjacent cells
