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lipids Flashcards

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Organic Chemistry 101 flashcards
1
Q

are lipids polymers

A

no,they are macromolecules

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2
Q

are lipids polar or non polar

A

non-polar,they are insoluble in water

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3
Q

what are fats and oils composed of

A

tryglycerides

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3
Q

what is the name for molecules which are insoluble in water,non-polar

A

hydrophobic molecules-meaning repelled by water

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4
Q

What elements are lipids made of

A

C,H,O with lower proportion of oxygen compared to carbohydrates

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5
Q

what are the two main groups of lipids

A

-triglycerides
-phospolipids

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6
Q

what are the functions of lipids

A

-energy source
-store of energy
-insulation -both thermal under the skin and electrical around nerve cells
-structurally important in biological membranes
-important in hormonal communication
-hormone production

-waterproofing like on plant leaves- the hydrophilic heads face the water at each bilayer surface, and the hydrophobic tails are shielded from the water in the interior.

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7
Q

are triglycerides hydrophobic and non-polar

A

yes

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8
Q

what are the monomers of triglycerides

A

fatty acids and glycerol,more specifically 3, fatty acids and one glycerol molecule

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8
Q

what is the hydrocarbon chain also known as

A

R group

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9
Q

what is glycerol

A

its an alcohol,an organic compound

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9
Q

what is the structure of glycerol

A

3 carbon atoms ,located beneath each other and ,with each carbon joined to a hydroxyl groups ,the rest is hydrogen atoms

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9
Q

what is the structure of a fatty acid

A

it consists of a hydrocarbon chain,also known as an R group which is joined to a carboxyl group(COOH) at the end of the molecule

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10
Q

what is the chemical formula for a fatty acid

A

RCOOH

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11
Q

how are fatty acids different from one another (2 ways)

A

-the length of their hydrocarbon chain can differ
-the hydrocarbon chain of the fatty acids can be either unsaturated or saturated

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12
Q

what are saturated fatty acids knwon to make

A

animal fat

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13
Q

what are unsaturated fatty acids known to make

A

oils

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14
Q

what is meant by an unsaturated fatty acid

A

The hydrocarbon chain of the fatty acid contains at least one carbon-carbon double bond; it is not bonded to as many hydrogens
as possible due to the presence of a double bond

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14
Q

what is meant by a saturated fatty acid

A

-the hydrocarbon chain does not have carbon-carbon double bonds, and it is bonded to as many hydrogen atoms as possible

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14
Q

what are the two types of unsaturated fatty acids

A

-monounsaturated
-polyunsaturated

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15
Q

What is it meant by monounsaturated fatty acids

A
  • a fatty acid which hydrocarbon chain contains one carbon-carbon double bond
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16
Q

why are saturated fatty acids described as fats not oils

A

Saturated fatty acids do not contain any carbon-carbon double bonds within the fatty acid chain and are thus the carbon atoms are bonded to the maximum number of hydrogen atoms.This means that saturated fatty acids form starts ight chains,which are able to pack closely together,so they have stronger intermolecular forces present between molecules.So more energy is required to overcome,which is why they are solid at room temperature and thus described as fats not oils.

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16
Q

why are unsaturated fatty acids described as oils not fats

A

unsaturated fatty acids contain sat least one carbon-carbon double bond within the fatty acid chain and so the carbons do not form the maximum number of bonds with hydrogen atoms.The presence of a double bond causes the chain to kink/bend , so it can no longer pack as closely together .This weakens the intermolecular forces present between molecules so that less energy is required to overcome them,explaining why unsaturated fatty acids are liquid at room temp and thus described as oils not fats

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17
Q

are lipids soluble in water

A

no,thus have no osmotic effect on cells

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18
Q

describe what happens in esterification,and what forms as a result.

A

When close to each other, the hydroxyl group of glycerol interacts with the hydroxyl group of fatty acids in a condensation reaction known as esterification. This forms three ester bonds and releases three molecules of water .

This causes one glycerol molecule to bond to three fatty acids, forming a triglyceride.

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19
Q

how does water form

A

a hydrogen atom of glycerol bonds to hydroxyl group of a fatty acids to form water molecule.

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19
Q

what is the enzyme that breaks ester bonds

A

lipase

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20
Q

describe the hydrolysis reaction,that happens to break a triglyceride into one glycerol molecule and 3 fatty acids

A

In a hydrolysis reaction ,3 molecules of water are added to break the 3 ester bonds present between glycerol and fatty acids ,breaking the triglyceride into one glycerol an d3 fatty acids

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21
Q

What is the structure of a triglyceride

A

one glycerol molecule bonded to 3 fatty acids makes up a triglyceride

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21
Q

what is the name of the hydrolysis reaction which breaks down triglycerides into fatty acids and glycerol

A

lipolysis

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22
Q

what are the functions of triglycerides

A

-store of energy
-protection
-insulation
-buoyancy
-source of energy(less important)

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23
Q

triglycerides as good storage molecules

A

-the hydrocarbon tails of triglycerides are made up of many C-H bonds,meaning that it stores a lot of chemical energy.This energy is released when triglycerides are
broken down via oxidised during respiration
This energy is released because which the C-H bonds which contain the energy break, the energy is used for production of ATP

-The hydrocarbon tails of triglycerides result in triglycerides storing more energy per gram than carbohydrates ,proteins ,twice as much

-Triglycerides are also hydrophobic,so they are insoluble in water,meaning that they have no osmotic effect on cells(don’t cause water to enter cells by osmosis,causing them to swell)

In water triglycerides bundle together ,with their hydrophobic fatty acids tails facing inwards,shielded from water by their glycerol heads

24
Q

what is metabolic water,how is it released,and why is it useful

A

The oxidation of C-H bond during respiration releases a lot of energy,but also many molecules of water which are known as metabolic water

-Desert animals use metabolic water when there is no water available to drink

24
Q

how do plants store triglycerides

A

they store triglycerides int he form of oils in their seeds and fruits

25
Q

why when we extract oil from seeds of a plant ,why is it liquid

A

the fatty acid chaoins contains a double bond,causes the chain to kind so cant pack closely together,meaning that less energy is required to overcome the intermoleculr forces, so liquid at room temperatue

25
Q

how do mammals store triglycerides and how are they used

A

they are stored as oil droplets in adipose tissue.They are broken down via oxidation in respiration when food is scarce to release energy.

HOW OUR BODY CONVERTS FAT TO ENERGY

25
Q

triglycerides acting as a thermal insulation layer

A

triglycerides are part of the composition of adipose tissue,the layer under the skin,they acy as a thermal insulation layer,preventing heat loss from the body

26
Q

describe how triglyceride have a protective role in the body

A

they make up part of the adipose tissue which helps protect organs from the risk of damage

27
Q

triglycerides acting as electrical insulating layer

A

triglycerides make up part of the myelin sheath ,which surrounds nerve fibres,It acts as an electrical insulating layer,increasing the speed of transition of nerve impulses

28
Q

desribe triglycerides and buoyancy

A

Lipids have low density,particularly fat tissue, so they help increase the ability of animals to float more easily

29
Q

whats the structure of a phosholipids

A

Two fatty acids bond to one glycerol, and the glycerol bonds to a phosphate group-PO4 3-

30
Q

how are phospholipids and triglycerides different

A

-triglyceride made of 3 fatty acids and glycerol,whereas phospholipids are made of 2 fatty acids,glycerol and a phosphate group

-phospholipids are both polar and non-polar ,whereas triglycerides are just non-polar

-different roles,triglycerides main role is as a store of energy,whereas phospholipids main role is that they are the main component of cell membranes,make up the phospholipid bilayer

31
Q

describe the fatty acid tails of the phospholipid

A

-they are non-polar,hydrophobic menaing that they repel water,thus they are not soluble in water,however they can dissolve in fats

32
Q

describe the phosphate head of the phospholipid

A

-polar ,hydrophillic meaning that it is attracted to water,so water-soluble,however repels fats

33
Q

are phospholipids modified triglycerides

A

yes

34
Q

condensation reaction for phospholipids

A

3 ester bonds formed-even tho thye one between glycerol and phosphate group is called a phoshoester bond

-3 molecules of water released

35
Q

hydrolysis

A

-3 molecules of water required to break 3 ester bonds and split the phospholipid into fatty acids,glycerol and phosphate group

36
Q

how does a phosholipid have a dual nature

A

-phosphate head is polar,hydrophillic,whereas its fatty acid tails are hydrophobic,non-polar

36
Q

how is the water molecules of the phoshoester bond released

A
  • oh group of the phosphate bond with h atom of the glycerol to form water
37
Q

what do phospholipids form in water as result of their amphipathic nature

A

either a monolayer or a bilayer

38
Q

what is the word for having a dual nature

A

amphipathic,so phospholipids are amphipathic

39
Q

what is the shape of the micelle

A

sphere

39
Q

what is the monolayer called

A

a micelle

40
Q

what is the core of the micelle made of

A

hydrophobic,fatty acid tails thus noi water is found there

41
Q

how do phospholipids form a bilayer in water

A

Phospholipids are made of a hydrophilic phosphate head and hydrophobic fatty acid tails.In water, the hydrophobic fatty acid tails are repelled by water so face away from it and towards each other, forming the
hydrophobic core of the phospholipid bilayer

Whereas
the hydrophilic phosphate heads are attracted to water, so they face outwards and towards it, interacting and forming Hydrogen bonds with surrounding water molecules.

This results in the formation of the phospholipid bilayer which makes up cell membranes

42
Q

what is the function of phospholipids

A

-the main component of cell membranes, they make up the phospholipid bilayer, which’s hydrophobic core, which consists of hydrophobic fatty acid tails, acts as a barrier to water-soluble substances, allowing cell, membranes to control what substances enter and leave the cell

-the hydrophilic phosphate heads form H bond with water which allows cell membranes to PLAY A ROLE IN COMPARTMENTALISATION

43
Q

how do phospholipids control cell membrane protein orientation

A

there is weak hydrophobic interation between the phospholipid and proteins which hold the protein within the membrane,but allow it to move within the bilayer

43
Q

how does the composition of phospholipids effect the fluidity of cell membranes

A

-unsaturated fatty acids=more fluid
-saturated fatty acids=less fluid

44
Q

how do cell membranes control what enters and leaves cells

A

the hydrophobic fatty acid tails of phospholipids make the hydrophobic core of the phospholipid bilayer which acts as a barrier to water soluble substances preventing them from passing through easily.

44
Q

what is a steroid

A

type of lipid and a complex alcohol

45
Q

common structure of steroids

A

4 carbon rings attached to a hydroxyl group at one ned

46
Q

what group does cholesterol fall in

A

steroids

47
Q

do steroid have an amphipathic nature

A

yes ,they have both hydrophobic and hydrophilic parts

48
Q

how can steroid exists within the phospholipid bilayer

A

have dual nature,both hydrophobic and hydrophilic parts

48
Q

where is cholesterol manufactured

A

in the liver and instenstines

49
Q

how is cholesterol transported

A

via the blood

50
Q

What is the structure of cholesterol

A

has 4 carbon rings ,on one side they are attached to hydrocarbon tails and on the other to a hydroxyl group

50
Q

how is cholesterol amphipathic

A

the hydroxyl roup is polar so hydrophilic and the rest of the molecule is hydrophobic

51
Q

what allows cholesterol to fit between the fatty acid tails of phospholipids

A

its small size and flattened shape

52
Q

why is the hydroxyl group of cholesterol present at the periphery of the membrane

A

Because the hydrophilic phosphate heads form the two outside layers of the membrane

52
Q

where in the
phospholipid bilayer is cholesterol present

A

between the fatty acid tails of phospholipids

53
Q

what are the functions of cholesterol

A

-helps regulate the fluidity of cell membranes
- used to make steroid based hormones like oestrogen,progesterone and testosterone
-used to make vitamin D
-used to make bile in the liver

54
Q

what does bile do

A

increases the rate of digestion of lipids using the enzyme lipase

55
Q

how does cholesterol regulate the fluidity of cell membranes

A

at high temp, it binds to the fatty acid tails of phospholipids,causing them to pack closer together,thus reducing the fluidity of the membrane and making it more rigid

-at low temperatures, it prevents the fatty acid tails from packing too close together, increasing the fluidity of the cell membrane s

This way, cholesterol also helps maintains the stability of cells

56
Q

why are triglycerides known as energy reserves

A

have more energy per gram due to their hydrocarbon chain/tail

56
Q

how do you test for lipids

A

-Through the emulsion test

-First, use a pipette to add ethanol to a sample
-then shake to mix
-then add the mixture to a test tube of water

works as lipids are insoluble in water but soluble in organic solvents like ethanol

57
Q

what is a positive result

A

-a milky emulsion layer will form on top of the solution

-the more milky the solution the higher the concentration of the lipid present

58
Q

what is a negative result

A

-the solution will remain clear

biological molecules (14 decks)

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