Cell Membrane and Its Components (Unit 1)

Question 1

Cell membrane is made of?

Answer 1

Many different proteins embedded in the fluid matrix of the lipid bilayer

Question 2

Lipid bilayer

Answer 2

Main fabric of the membrane. Proteins are integrated into phospholipid bilayer

Question 3

Fluidity of membranes?

Answer 3

Not rigid. Lipids and proteins are free to move within the two layers

Question 4

Cell Membrane Model

Answer 4

Fluid mosaic model

Question 5

Fluid nature of bi-lipid layer depends on

Answer 5

Fatty acid (Saturated fatty acids = less fluid membrane, unsaturated fatty acids = more fluid membrane) Temperature (High is more, low is less)
Sterols (cholesterol prevents from becoming too fluid or rigid in temperatures)

Question 6

What makes the phospholipid bilayer semi permeable

Answer 6

Hydrophobic core prevents movement of hydrophilic structures, such as ions and polar molecules but allows hydrophobic molecules, which can dissolve in the membrane to cross it with ease.
Small polar molecules can slip through by fitting through open spaces in lipid bilayer

Question 7

Types of membrane proteins

Answer 7

Integral membrane proteins
Peripheral membrane proteins
Glycolipids and glycoproteins

Question 8

Integral Membrane Proteins

Answer 8

Span lipid bilayer (transmembrane proteins)
Nonpolar regions are embedded in the interior of the bilayer, while polar regions protrude from both sides of the bilayer
Interior of the protein is polar, allowing some polar molecules and ions to pass through the membrane

Question 9

Functions of integral membrane proteins

Answer 9

Transporter
Enzyme
Cell surface receptor
Cell surface identity marker
Cell to cell adhesion 
Attachments to the cytoskeleton

Question 10

Peripheral membrane proteins

Answer 10

Anchored to phospholipid in one layer of membrane or attached to an integral protein.
Posses polar regions inserted into the polar head region of the lipid bilayer
Free to move through one layer of bilayer

Question 11

Functions of peripheral membrane proteins

Answer 11

Receptor recognition and cell signalling
Promote conformation changes if protein structures to activate their biological activity
Carry electrons in electron transport chain (cytochrome c)

Question 12

Glycolipids and Glycoproteins

Answer 12

Lipids and proteins with a carbohydrate chain attached to it on the extracellular surface of the cell.
Sugar chains differ from species to species and from individual to individual within a species

Question 13

Functions of glycolipids and glycoproteins

Answer 13

Act as receptors
Help in cell recognition
Hormonal responses
Neurotransmission