lipids Flashcards
are lipids polymers
no,they are macromolecules
are lipids polar or non polar
non-polar,they are insoluble in water
what are fats and oils composed of
tryglycerides
what is the name for molecules which are insoluble in water,non-polar
hydrophobic molecules-meaning repelled by water
What elements are lipids made of
C,H,O with lower proportion of oxygen compared to carbohydrates
what are the two main groups of lipids
-triglycerides
-phospolipids
what are the functions of lipids
-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.
are triglycerides hydrophobic and non-polar
yes
what are the monomers of triglycerides
fatty acids and glycerol,more specifically 3, fatty acids and one glycerol molecule
what is the hydrocarbon chain also known as
R group
what is glycerol
its an alcohol,an organic compound
what is the structure of glycerol
3 carbon atoms ,located beneath each other and ,with each carbon joined to a hydroxyl groups ,the rest is hydrogen atoms
what is the structure of a fatty acid
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
what is the chemical formula for a fatty acid
RCOOH
how are fatty acids different from one another (2 ways)
-the length of their hydrocarbon chain can differ
-the hydrocarbon chain of the fatty acids can be either unsaturated or saturated
what are saturated fatty acids knwon to make
animal fat
what are unsaturated fatty acids known to make
oils
what is meant by an unsaturated fatty acid
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
what is meant by a saturated fatty acid
-the hydrocarbon chain does not have carbon-carbon double bonds, and it is bonded to as many hydrogen atoms as possible
what are the two types of unsaturated fatty acids
-monounsaturated
-polyunsaturated
What is it meant by monounsaturated fatty acids
- a fatty acid which hydrocarbon chain contains one carbon-carbon double bond
why are saturated fatty acids described as fats not oils
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.
why are unsaturated fatty acids described as oils not fats
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
are lipids soluble in water
no,thus have no osmotic effect on cells
describe what happens in esterification,and what forms as a result.
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.
how does water form
a hydrogen atom of glycerol bonds to hydroxyl group of a fatty acids to form water molecule.
what is the enzyme that breaks ester bonds
lipase
describe the hydrolysis reaction,that happens to break a triglyceride into one glycerol molecule and 3 fatty acids
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
What is the structure of a triglyceride
one glycerol molecule bonded to 3 fatty acids makes up a triglyceride
what is the name of the hydrolysis reaction which breaks down triglycerides into fatty acids and glycerol
lipolysis
what are the functions of triglycerides
-store of energy
-protection
-insulation
-buoyancy
-source of energy(less important)
triglycerides as good storage molecules
-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
what is metabolic water,how is it released,and why is it useful
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
how do plants store triglycerides
they store triglycerides int he form of oils in their seeds and fruits
why when we extract oil from seeds of a plant ,why is it liquid
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
how do mammals store triglycerides and how are they used
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
triglycerides acting as a thermal insulation layer
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
describe how triglyceride have a protective role in the body
they make up part of the adipose tissue which helps protect organs from the risk of damage
triglycerides acting as electrical insulating layer
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
desribe triglycerides and buoyancy
Lipids have low density,particularly fat tissue, so they help increase the ability of animals to float more easily
whats the structure of a phosholipids
Two fatty acids bond to one glycerol, and the glycerol bonds to a phosphate group-PO4 3-
how are phospholipids and triglycerides different
-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
describe the fatty acid tails of the phospholipid
-they are non-polar,hydrophobic menaing that they repel water,thus they are not soluble in water,however they can dissolve in fats
describe the phosphate head of the phospholipid
-polar ,hydrophillic meaning that it is attracted to water,so water-soluble,however repels fats
are phospholipids modified triglycerides
yes
condensation reaction for phospholipids
3 ester bonds formed-even tho thye one between glycerol and phosphate group is called a phoshoester bond
-3 molecules of water released
hydrolysis
-3 molecules of water required to break 3 ester bonds and split the phospholipid into fatty acids,glycerol and phosphate group
how does a phosholipid have a dual nature
-phosphate head is polar,hydrophillic,whereas its fatty acid tails are hydrophobic,non-polar
how is the water molecules of the phoshoester bond released
- oh group of the phosphate bond with h atom of the glycerol to form water
what do phospholipids form in water as result of their amphipathic nature
either a monolayer or a bilayer
what is the word for having a dual nature
amphipathic,so phospholipids are amphipathic
what is the shape of the micelle
sphere
what is the monolayer called
a micelle
what is the core of the micelle made of
hydrophobic,fatty acid tails thus noi water is found there
how do phospholipids form a bilayer in water
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
what is the function of phospholipids
-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
how do phospholipids control cell membrane protein orientation
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
how does the composition of phospholipids effect the fluidity of cell membranes
-unsaturated fatty acids=more fluid
-saturated fatty acids=less fluid
how do cell membranes control what enters and leaves cells
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.
what is a steroid
type of lipid and a complex alcohol
common structure of steroids
4 carbon rings attached to a hydroxyl group at one ned
what group does cholesterol fall in
steroids
do steroid have an amphipathic nature
yes ,they have both hydrophobic and hydrophilic parts
how can steroid exists within the phospholipid bilayer
have dual nature,both hydrophobic and hydrophilic parts
where is cholesterol manufactured
in the liver and instenstines
how is cholesterol transported
via the blood
What is the structure of cholesterol
has 4 carbon rings ,on one side they are attached to hydrocarbon tails and on the other to a hydroxyl group
how is cholesterol amphipathic
the hydroxyl roup is polar so hydrophilic and the rest of the molecule is hydrophobic
what allows cholesterol to fit between the fatty acid tails of phospholipids
its small size and flattened shape
why is the hydroxyl group of cholesterol present at the periphery of the membrane
Because the hydrophilic phosphate heads form the two outside layers of the membrane
where in the
phospholipid bilayer is cholesterol present
between the fatty acid tails of phospholipids
what are the functions of cholesterol
-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
what does bile do
increases the rate of digestion of lipids using the enzyme lipase
how does cholesterol regulate the fluidity of cell membranes
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
why are triglycerides known as energy reserves
have more energy per gram due to their hydrocarbon chain/tail
how do you test for lipids
-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
what is a positive result
-a milky emulsion layer will form on top of the solution
-the more milky the solution the higher the concentration of the lipid present
what is a negative result
-the solution will remain clear
