Membrane Structure 1.3

Question 1

Phospholipids

Answer 1

Phospholipids, aref lipids whose molecule has a hydrophilic “head” containing a phosphate group and two hydrophobic “tails” from fatty acids,

Question 2

Phospholipid bilayers

Answer 2

The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules

Question 3

Polar vs Non Polar

Answer 3

Polar: A structure having an uneven distribution of electron density.
A structure in which electron density is more or less evenly distributed is called nonpolar.

Question 4

Amphipathic

Answer 4

Has both Hydrophilic and Hydrophobic Parts

Question 5

Hydrophilic

Answer 5

Water loving - attracted to water molecules and tends to be dissolved by water = Polar

Question 6

Hydrophobic

Answer 6

Property of a substance that repels water. It means lacking affinity for water, and tending to repel or not to absorb water.

Hydrophobic molecules tend to be non-polar molecules and group together.

Question 7

The Phospholipid Head

Answer 7

Phosphate group bonded to glycerol

Heads attract water molecules

Question 8

The Phospholipid Tail

Answer 8

It is hydrophobic meaning that it does not attract water

Made of 2 fatty acids

Question 9

Gorter and Grendel Model

Answer 9

Founders of the “Bi-layer” model
Extracted phospholipids from red blood cell
Very Simple

Question 10

Davson-Danielli Model

Answer 10

Showed how there were no integral, peripheral and lipid (Diamond shape) proteins to the structure of the membrane

Falsified as the fluid mosaic model made more sense

Question 11

Fluid Mosaic Model

Answer 11

Showed how there has a phospholipid bi - layer and integral, peripheral and lipid proteins. Also had glycogen chains, cholesterol and kinks in tail for space of cholesterol.

Integral proteins could be channel, carrier or a pump.

Question 12

Simple Diffusion

Answer 12

simple diffusion is a form of diffusion that does not require the assistance of membrane proteins.

Question 13

Facilitated Diffusion

Answer 13

Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral

Needs integral protein as the transport vesicles are to big to simply go through the heads

Question 14

Passive Transport

Answer 14

Passive transport is a type of membrane transport that does not require energy to move substances across cell membranes.

Instead of using cellular energy, like active transport, passive transport relies on the second law of thermodynamics to drive the movement of substances across cell membranes.

Question 15

Active Transport

Answer 15

Occurs when molecules such as glucose or amino acids move from high concentration to low concentration facilitated by carrier proteins or pores in the membrane.

Active transport requires energy for the process by transporting molecules against a concentration or electrochemical gradient.

Question 16

Concentration gradient

Answer 16

A concentration gradient occurs when the concentration of particles is higher in one area than another.

Like the unequal distribution of ions on one side of the membrane

Question 17

Hydrocarbon Tail

Answer 17

The hydrocarbon chain that makes up fatty acids

Making the tail end of the molecule hydrophobic, or water resistant, while the glycerol head is hydrophilic, or “water-loving.” These properties are due the polarity of the molecules that make up each side

Question 18

Saturated vs Unsaturated

Answer 18

The difference between saturated and unsaturated fat lies in the number of double bonds in the fatty acid chain. Saturated fatty acids lack double bonds between the individual carbon atoms, while in unsaturated fatty acids there is at least one double bond in the fatty acid chain.

Unsaturated would have a double bond when the chemical is kinked downwards (C is double bonded)

Question 19

Functions of Membrane Proteins

Answer 19

Junctions – Serve to connect and join two cells together
Enzymes – Fixing to membranes localises metabolic pathways
Transport – Responsible for facilitated diffusion and active transport
Recognition – May function as markers for cellular identification
Anchorage – Attachment points for cytoskeleton and extracellular matrix
Transduction – Function as receptors for peptide hormones

JetRat***

Question 20

Membrane Fluidity

Answer 20

The plasma membrane is a fluid combination of phospholipids, cholesterol, and proteins

Question 21

Integral proteins

Answer 21

proteins embedded in the phospholipid bilayer.

Question 22

Peripheral proteins

Answer 22

proteins on the surface of the plasma membrane.

Question 23

Permeability

Answer 23

the rate of passive diffusion of molecules through the membrane, which depends on the electric charge, size, and polarity of the molecule.