lecture 4

Question 1

what is a fully saturated fatty acid

Answer 1

straight chain organic acids with an even number of carbon atoms

Question 2

what is an unsaturated fatty acid

Answer 2

a fatty acid with one or more double bonds between carbon atoms (permanent kink)

Question 3

what’s the difference between a cis and trans double bond

Answer 3

cis - hydrogen on same side, trans - hydrogen on different sides

Question 4

what are trans fatty acids

Answer 4

a result of a side reaction with the catalyst of the hydrogenation process, results in a cis double bond being converted to a trans double bond.

Question 5

how do you name fatty acids in the delta format

Answer 5

number of carbons:number of double bonds . isomerism of double bonds - capital delta symbol ^ first carbon of each double bond (from carboxyl end)

Question 6

how do you name fatty acids in the omega format

Answer 6

lowercase omega symbol-first carbon of first double bond from methyl end

Question 7

what are triglycerides

Answer 7

Esthers of glycerol (alcohol) and three fatty acids

Question 8

what are phospholipids

Answer 8

a group of polar lipids that consist of two fatty acids, a glycerol unit and a phosphate group

Question 9

what are sphingolipids

Answer 9

a class of lipids containing a set of aliphatic amino alcohols that includes sphingosine

Question 10

what is a micelle

Answer 10

a lipid molecule that has hydrophilic head groups on the outside and hydrophobic hydrocarbon chains on the inside

Question 11

what is a bilayer membrane

Answer 11

a thin polar membrane made of two layers of lipid molecules, head groups on outside, hydrocarbon chains on inside (hydrocarbon chains too long for micelle formation)

Question 12

what is a liposome

Answer 12

a spherical vesicle used in drug delivery composed of one of more phospholipid bilayers. has an aqueous environment inside and outside liposome

Question 13

what is cholesterol

Answer 13

a major component of eukaryotic cell membranes, has a polar head and non-polar hydrocarbon tail

Question 14

what is the plasma/cell membrane

Answer 14

the membrane found in cells that separates the interior of the cell from the outside environment, made of lipids and proteins

Question 15

what are peripheral proteins

Answer 15

proteins temporarily found in the plasma membrane that bind via covalent, non-covalent, ionic or hydrogen bonding interactions

Question 16

what are integral proteins

Answer 16

transport proteins permanently embedded within the plasma membrane that move solute molecules from one side of the membrane to the other

Question 17

what is glycophorin

Answer 17

an integral protein found in the membranes of red blood cells

Question 18

how long is the alpha helix that sits within the membrane

Answer 18

20 amino acids long

Question 19

how long is beta barrel conformation

Answer 19

7-9 residues across the membrane

Question 20

what does the fluid mosaic model describe and include

Answer 20

the structure of the plasma membrane as a mosaic of components including phospholipids, cholesterol, proteins and carbohydrates

Question 21

what three factors affect the fluidity of a membrane

Answer 21

temperature (heat increases = more fluid), fatty acid saturation (saturated fatty acids packed together more tightly = rigid and ordered, unsaturated fatty acids are kinked so less packed = more fluid), sterols (can pack unsaturated fatty acids = less fluid, associate with saturated fatty acids = more fluid)

Question 22

how are lipids distributed

Answer 22

into micro domains, which are thicker and more ordered therefore less fluid. micro domains are rafts in sea of fluid phospholipids and keep lipid molecules together

Question 23

what is lateral diffusion

Answer 23

when phospholipid moves through the membrane, remaining on the same side of the bilayer

Question 24

what type of molecule can easily diffuse through the plasma membrane

Answer 24

small, non polar molecules and water molecules

Question 25

what is passive transport

Answer 25

simple/facilitated diffusion, solute moves down a concentration/ electrical gradient - no energy expenditure

Question 26

what are permeases

Answer 26

transporter proteins that lower the activation energy and increase the rate of diffusion

Question 27

what is active transport

Answer 27

transport against a concentration gradient - thermodynamically unfavourable and requires energy