LIPIDS

Question 1

What makes lipids insoluble in water?

Answer 1

Hydrophobic properties

Question 2

Lipids charge

Answer 2

Neutral, no electrical charge = nonpolar

Question 3

Lipids cannot form what type of bonds with water?

Answer 3

Hydrogen bonds

Question 4

The nonpolar nature of lipids:

Answer 4

Enables them to interact among themselves to assemble into fat droplets or the lipid bilayer of the cell membrane

Question 5

3 major groups of lipids

Answer 5

-Phospholipids
-Steroids
-Triglycerides

Question 6

Phospholipids

Answer 6

-Essential components of cell membranes
-Hydrophilic head, hydrophobic tail→ forms bilayer that separates the inside of the cell from its external surroundings
-The lipid bilayer acts as a barrier and facilitates the regulated movement of substances in and out of the cell

Question 7

Steroids

Answer 7

-Four ring structure
-Regulation (sex + stress hormones)
-Medical use: reducing inflammation, suppressing immunity to prevent the rejection of transplanted organs

Question 8

Triglycerides

Answer 8

-3 fatty acid chains attached to a glycerol molecule
-Compact, energy rich
-Insulation to retain body heat
-Physical protection of organs

Question 9

Hydrogen bonding

Answer 9

Weak bond between a hydrogen atom and another electronegative atom

Question 10

What prevents nonpolar lipids from interacting with polar water molecules?

Answer 10

-Lipids lack charges or polar groups to form hydrogen bonds with water
-Water prefers interacting with other polar molecules

Question 11

What is the hydrophobic effect?

Answer 11

-Due to the physical repulsion among hydrophobic molecules and polar molecules like water
-The tendency of nonpolar molecules to clump together in water, minimizing their surface area exposed to water

Question 12

What is the biological relevance of the hydrophobic effect?

Answer 12

-Enables phospholipid molecules to form the lipid bilayer
-Contributes to proteins folding into their functional 3D form

Question 13

Why does life require hydrophobic biological molecules?

Answer 13

Help form cell membranes, provide insulation, store energy efficiently

Question 14

Functions of lipids in animals:

Answer 14

-Retain body heat
-Reduces waterlogging of feathers/fur
-Maintains fur/feather integrity
-Reduces colonization by microbes/small pests to reduce risk of infection

Question 15

Functions of lipids in plants:

Answer 15

-A waterproof layer of lipids covers the surface of plant organs (leaves, fruits, stems, roots)
-The waterproof cuticle layer reduces the risk of dehydration + infection

Question 16

Which four vitamins are lipids?

Answer 16

A, D, E, K
Stored primarily in liver and fat cells

Question 17

What vitamins regulate transcription?

Answer 17

A, D, E

Question 18

What vitamin is a cofactor that activates enzymes?

Answer 18

K

Question 19

Vitamin A

Answer 19

Vision, skin rejuvenation, bone & tooth growth, reproduction, immunity

Question 20

Vitamin D

Answer 20

Mineralization of bones (strong bones), immune & neuromuscular function

Question 21

Vitamin E

Answer 21

-Antioxidant, stabilization of cell membranes (healthy cells = healthy body)
-Reduces risk of mutation, alteration

Question 22

Vitamin K

Answer 22

-Synthesis of blood clotting proteins and bone proteins
-Bind to enzymes, activates the enzymes
-Microbiome secretes K

Question 23

Which disorders are due to the insufficient intake of lipid soluble vitamins?

Answer 23

-A: night blindness
-D: rickets
-K: clotting problems

Question 24

Two branches of triglycerides

Answer 24

Fats, oils

Question 25

Fats

Answer 25

-Form solids at room temp
-Butter, lard
-Saturated: fatty acids with single bonds between all carbon pairs

Question 26

Oils

Answer 26

-Form liquids at room temp
-Olive oil
-Unsaturated: fatty acids that contain double bonds between one or more pairs of carbon atoms

Question 27

Why do animals store most excess food energy as triglycerides?

Answer 27

Triglycerides store more energy per gram than carbs are are lightweight, making them efficient for long term storage

Question 28

In which human tissue, cell type, and organelle are triglycerides stored?

Answer 28

Adipocytes

Question 29

Which property of phospholipids enables them to interact to form the lipid bilayer?

Answer 29

Hydrophilic (polar) heads and hydrophobic (nonpolar) tails allow them to form bilayers in water

Question 30

Which two types of lipids form cell membranes?

Answer 30

-Phospholipids
-Steroids (cholesterol)

Question 31

Cholesterol

Answer 31

-Cell membranes
-Building block to make other steroids

Question 32

Cortisol

Answer 32

Stress response

Question 33

Vitamin D2

Answer 33

Calcium uptake by intestines

Question 34

Testosterone/estrogen

Answer 34

Reproduction

Question 35

How does cholesterol contribute to the function of your cell membranes?

Answer 35

It stabilizes membrane fluidity, preventing membranes from becoming too rigid in cold or too fluid in heat

Question 36

% of lipids of daily caloric intake

Answer 36

~20-35%

Question 37

The acid mantle

Answer 37

-pH: 5.5
-Fatty acid layer on skin that reduces risk of infection
-Sebum contains fatty acids and triglycerides
-Sweat contains fatty acids

Question 38

Earwax

Answer 38

-Lines the inner surface of the ear canal to reduce risk of infection
-Fatty acids, cholesterol

Question 39

What vitamin allows our photoreceptors to detect light and enable vision?

Answer 39

Vitamin A (retinol)

Question 40

Phospholipid structure

Answer 40

3 carbon glycerol
2 fatty acids
1 phosphate

Question 41

Charge of the outer region of bilayer

Answer 41

Negative