Cellular Communication and Signaling Flashcards
What are microvilli?
Microvilli are tiny, hair-like projections on the surface of certain cells, primarily epithelial cells lining the intestines and other absorptive surfaces.
They are designed to increase the surface area of the cell, thereby enhancing its ability to absorb nutrients and other substances. Each microvillus contains a core of actin filaments that provide structural support.
What is the lipid bilayer permeable and impermeable to?
Permeable to: Non-polar, uncharged molecules
Impermeable to: Ions and large, charged molecules
Are the phospholipid byliayer choline heads polar or non polar?
Polar = hydrophilic = water loving
*Hydrophilic heads and hydrophobic tails.
Are the fatty acyl tails of the bilayer polar or non polar?
Nonpolar = hydrophobic = water hating = prevent water soluble solutes from passing though the middle of the bilayer.
Can ions and glucose cross the lipid bilayer?
No
Can O2, CO2 and steroid hormones cross the bilayer?
Yes
What percentage of the lipid bilayer is phospholipids?
75%
What percentage of the lipid bilayer is cholesterol?
20%
What makes up 5% of the lipid bilayer?
Glycolipids
What is the composition of the head of glycolipids?
Sugar (such as galactose)
What is the composition of the head of phospholipid?
Alcohol and phosphate
What is the composition of the head of cholesterol?
OH group
What does the cell membrane form?
A semi-permeable barrier
What makes up the cell membrane?
Lipid bilayer + membrane proteins
What are membrane proteins purpose?
Communication and exchange
What is on either side of a cell membrane?
Extracellular fluid/space
Cytosol
What principle is “Brownian motion” used to describe?
Everything is in constant motion - in the context of the cell membrane it is referring to the fact that the lipids in the bilayer and the membrane proteins are fluid/flexible.
It is important that the small molecules are flexible and dynamic for changing protein and lipid populations, cell growth, secretion and self-sealing
What side of the membrane are microvilli?
Apical
Where does epithelia sit?
ON an extracellular matrix structure called the basement membrane or basal lamina.
What joins the basal lamina to epithelial cells?
Hemidesmosomes
What does the basement membrane/basal lamina prevent?
Cell movement
What proteins are made in and secreted from epithelial cells?
Collagen and Laminin
What causes epidermolysis bullosa?
A collagen malfunction meaning that the basement membrane is no longer attached to skin epithelia
What is the predominant symptom resulting from epidermolysis bullosa?
Blistering