Term 1- Lec 5- Cell Membranes

Question 1

Components of Glycerophospholipids

Answer 1

2 FAs—Glycerol—Phosphate—X ; X can be choline, serine, etc. (Phosphatidylcholine, Phosphatidylserine)

Question 2

Components of Sphingolipids

Answer 2

1 FA—Sphingosine (contains one long chain)—Phosphate—X. Ex: Sphingomyelin, Glycosphingolipids.

Question 3

What is the most abundant lipid in membranes?

Answer 3

Glycerophospholipids (The typical phospholid shown in diagrams)

Question 4

What is characteristic of glycophospholipids and why is it crucial to membrane properties/structure?

Answer 4

ONE of the FA tails has one or more CIS- bonds that cause a kink in the structure. This allows them to remain fluid for a wider range of temperatures.

Question 5

What is the backbone of a glycophospholipid?

Answer 5

Glycerol

Question 6

What is the backbone of a sphingolipid?

Answer 6

Sphingosine

Question 7

Ceramide is made up of what two structures?

Answer 7

Sphingosine and a FA chain

Question 8

Adding a sugar to ceramide creates what? What are these precursor to?

Answer 8

Glycolipids. They are found most commonly in NERVE TISSUES. They are precursors for Cerebrosides and Gangliosides.

Question 9

What lipids are important in nerve tissues and prevalent in brain cell membranes?

Answer 9

Cerebrosides

Question 10

What are the most complex sphingolipids; found primarily in a certain type of cells in the CNS? What type of cell are they primarily in?

Answer 10

Gangliosides. They are found in Ganglion Cells.

Question 11

What are the components of Cholesterol?

Answer 11

1 FA—steroid ring structure—small polar head.

Question 12

What effet does cholesterol have on membrane fluidity?

Answer 12

At High T, it prevents the membrane from becoming too fluid. At Low T, it lowers the point at which membranes become gel-like.

Question 13

What membrane components are most common in the outer leaflet of the cell membrane?

Answer 13

Sphingomyelin, Glycolipid, Phosphatidylcholine, and Cholesterol

Question 14

What membrane components are most common in the inner leaflet of the cell membrane?

Answer 14

Phosphatidylserine, Phosphatidylinositol, and Phosphatidylethanolamine

Question 15

What are the components of Sphingomyelin?

Answer 15

(1 FA—Sphingosine)=Ceramide—Phosphate—Choline

Question 16

What are the common components of a Lipid Raft?

Answer 16

Sphingomyelin, Glycolipids, Cholesterol, and GPI-anchored proteins

Question 17

What processes are lipid rafts necessart for?

Answer 17

Endocytosis and Receptor-Mediated Signaling

Question 18

5 types of movement exhibited by glycerolphospholipids and sphingolipids?

Answer 18

Lateral Diffusion, Rotation, Swing (tails swinging), Flexion (compression of tails), Transverse (flip-flop)

Question 19

What determines much of the functions of a membrane?

Answer 19

Protein portions. i.e. Myelin membrane is ~25% protein and Inner Mitochondrial membrane is ~75%

Question 20

What membrane component anchors most proteins to the outer leaflet?

Answer 20

GPI—Glycophosphatidylinositol.

Question 21

What is good about proteins being connect to GPI on the outer leaflet of a membrane?

Answer 21

Proteins in the membrane can quickly cleave the GPI-Protein bond to release the protein into the Extracellular space.

Question 22

3 movements that membrane proteins can exhibit

Answer 22

Rotational, Lateral movement, Conformational changes (transport proteins)

Question 23

Carbohydrates can only be found on which surface of the cell membrane?

Answer 23

Extracellular surface (Noncytoplasmic)

Question 24

Where and What is the Glycocalyx?

Answer 24

Located extracellularly. It is a carbohydrate-rich zone just off of the cell membrane.

Question 25

What enzymatic reaction is crucial to the formation of the glycocalyx?

Answer 25

Glycosylation

Question 26

What are the 3 main functions of the Glycocalyx?

Answer 26

Cell recognition, Cell signaling, and Water Absorption

Question 27

The glycocalyx of RBC’s determines

Answer 27

ABO blood types

Question 28

The 3 functions of glycocalyx in the intestines

Answer 28

• Provides an additional surface that aids in absorption
• Contains enzymes that aid in digesting macromolecules
• Protects enterocytes from friction and digestive enzymes

Question 29

Lipid associated diseases (2)

Answer 29

Multiple Sclerosis and Niemann-Pick Disease

Question 30

Membrane Protein associated diseases (3)

Answer 30

Cystic Fibrosis, Duchenne, Muscular Dystrophy

Question 31

Glycosylation-related diseases (1)

Answer 31

Congenital disorders of Glycosylation

Question 32

Multiple Sclerosis

Answer 32

An autoimmune response that leads to the destruction of myelin producing cells. Demyelinated nerve cells struggle to transmit nerve signals.

Question 33

Niemann-Pick Disease: Types A and B

Answer 33

Sphingomyelinase deficiency leads to accumulation of sphingomyelin in the spleen, liver, lungs, bone marrow, and brain causing irreversible brain damage. Type A: Infants. Type B: Pre-teen.

Question 34

Cystic Fibrosis

Answer 34

Defective Cl- transporters in epithelial cells result in abnormally thick, sticky mucus that obstructs respiratory pathways.

Question 35

Congenital Disorders of Glycosylation (CDG)

Answer 35

Defects in the glycosylation pathway leads to abnormal glycocalyces (glycocalyx-es).