Cell Membrane Structure Student Version-1

What is the cell membrane composed of? Descibe its structure

phospholipids (hydrophillic head, hydrophobic tail) (major lipid component) and sphingolipids (found in Nervuos system). The cell membrane is a lipid bilayer with an inner and outer leaflet.

Describe the relative amount of carb, protein, and lipids within the cell membrane

most is proteins, close to proteins is lipids, and few carbohydrates

What are glycocalx and why are they important?

glycocalx = glycocarbohydrates and glycoproteins. The variability of these carbohydrates are important for cell recognition

Where do lipid/protein composition differ?

amongst the same cell type (membrane of mitochondria has more proteins in it because of the Electron Transport Chain) and amongst cell within same organism (cell membrane of myelin shealth has more lipids)

In the cell membrane, what are the functions of Lipids?

structural, as energy by fatty acid degradation, as reservoir of signaling molecules (arachidonic acids is a precursor of eioscanoids) and as antioxidants (beta-carotene and unsat. FA)

Describe what a phospholipid is composed of. What can the polar head be?

glycerol, fatty acid, polar head, phospheric acid. choline, serine, ethanolamine, glycerol, insitol

What is the lecithin:sphingomyelin ratio used clinically for? Why? What phospholipid is this lecithin?

used to determine lung maturity in fetus to determine optimum time for an early elective delivery. It is the phospholipid attached to choline (dipalmitoylphosphatidylcholine). This is because lechtin makes up 50% of surfactants

What is the most common polar head in plasmogen? Where is this phospholipid often found? What is the clinical significance of plasmogens? Symptoms

ethanolamine. Found in inner leaflet. Plasmogens are important because mutations in their biosynthesis leads to RCDP (rhizomatic chondrodysplasia). Symptoms = skeletal abnormality, learning disability, distinctive facial features and respiratory problems

What phospholipid plays a role in cell apoptosis? Where is this phospholipid found? How can this phospholipid be detected in the lab?

The one with Serine (Phosphatidylserine (PS)). Found in inner leaflet. Can be detected via annexin V assay.

what phospholipid is essential for the synthesis in secondary messengers? Give an example

Inisotol (phosphatidylinositol). PIP2

Which phospholipid makes up a majority of sulfactant? What does surfactant do? What is this phospholipid used in?

Phosphotidylglycerol. Surfactant decreases surface tension within alveoli, preventing lungs to collapse upon itself. Used to assess fetal lung development

in the membrane phospholipid, where are fatty acids bound? How are they transported in the blood stream? What is their energetic form?

C1 and C2 of glycerol. In blood stream, bound to albumin or lipoprotein. They are tricylcerides in cells where they are a form of energy storate.

What is the relationship between saturated FA and fluidity? What is the side effect of this?

sat. FA = solidity of cell membrane. This decreases protein movement and ion transport

What is the relationship between unsat. FA and fluidity? What is the side effect of this?

unsat. FA = more fluidity. This also leads to facilitation of transport

What do Trans fat act as?

Trans fat are fats with a double bond but they acts as saturated FA

What is the function of sphingolipids? What is the backbone? how is this made?

Function: can be receptors for bacteria/virus toxins, Intracellular communication and determinets of ABO group.

backbone: sphingosine. Made: serine + paltyml Coa

How is cholesterol found in the plasma membrane

free-bound or esterfied with fatty acid

discuss the structure, polarity and function of cholesterol

rigid four ring structure. weakly Amphiatic, plays a role in fluidity of plasma membrane

what are the three types of proteins found in the plasma membrane and what are their functions. What is a prion?

integral: channels, receptors, transportors, and structural

peripheral: released by ionic solvents

lipid-bound: may be involved in hormone regulation

prion = lipid anchored protein

explain the pathology of spherocytosis

in the RBC, transport proteins need band3, akryin, and spectrin. Mutation in the heads of these will causes abnormal shape and rigidity in RBC —→ hemolysis of blood

what does deficiency in GLUT-1 lead to?

learning disabilities and seizures because of decreased glucose in CSF

explain the pathology of cycstic fibrosis

CFTR gene mutated, cl- channels function affected

what is an important component of myelin shealth and how is that made?

sphingomyelin.

serine + PaltimylCoa = sphingoserine —→Sphingoserine + any FA = ceramide —> Ceramide + phosphatidyl choline

what causes lysosomal storage disease? What is it also known as?

Sphingolipids are degraded by lysosomal enzyme. Degradation of this enzyme causes sphingolipidosis.

phosphatidylcholine

sphingomyelin

ethanolamine

serine

inisitol

glycerol