3.1.3 Lipids Flashcards
The 2 main groups of lipids that I need to know are… and…
Triglycerides
Phospholipids
The 2 main groups of lipids I need to know are triglycerides and…
Phospholipids
When drawing fatty acids, the letter ‘R’ represents….and is followed by COOH (carboxylic acid)
A long hydrocarbon chain
When drawing fatty acids, the letter ‘…’ represents a long hydrocarbon chain and is followed by COOH (carboxylic acid)
R
The role of triglycerides is…
Energy storage
True or false the ‘R’ group of a fatty acid (the long hydrocarbon chain) is always saturated
False, it can either be saturated or unsaturated
The…of a fatty acid can either be saturated or unsaturated
R-group
A condensation reaction between glycerol and a fatty acid forms a…bond
Ester
A…reaction between glycerol and a fatty acid forms an ester bond
Condensation
RCOOH represents….
A fatty acid
(Where R is the long hydrocarbon chain and COOH is the carboxylic acid)
RCOOH represents a fatty acid where R is the…and COOH is the…
Long hydrocarbon chain
Carboxylic acid
Triglycerides are formed by the condensation of on molecule of…and 3 molecules of…
Glycerol
Fatty acids
Triglycerides are formed by the condensation of one…of glycerol and 3…of fatty acid
Molecule(s)
Type of bond between fatty acid and glycerol
Ester
Saturated fatty acids vs unsaturated fatty acids
Saturated= no double carbon bond (form linear hydrocarbon chains)
Unsaturated= at least one double carbon bond (hydrocarbon chains can bend)
Which type of fatty acid out of saturated and unsaturated doesn’t contain any double carbon bonds
Saturated= no double carbon bonds
Which type of fatty acid out of saturated and unsaturated contains at least one double carbon bond
Unsaturated
Saturated fatty acids have no double carbon bonds so form hydrocarbon chains that are ….(what shape)
Linear
Unsaturated fatty acids have at least one double carbon bond so the hydrocarbon chains can…(think about the shape)
Bend
.. fatty acids form linear hydrocarbon chains but …..fatty acids form hydrocarbon chains that can bend
Saturated
Unsaturated
Triglycerides are…in water so are described as hydrophobic
Insoluble
Triglycerides are insoluble in water so are described as …
Hydrophobic
Triglycerides are insoluble in water so are described as …
Hydrophobic
The role of phospholipids is…
Structural role
In phospholipids, one of the fatty acids of a triglyceride is substituted by…
A phosphate containing group
…..are composed of glycerol, 2 fatty acids and a phosphate group
Phospholipids
Phospholipids are the main component of …(part of cell)
Cell membrane
…are the main component of cell membranes
Phospholipids
True or false, phospholipids are fully hydrophobic
False
The fatty acids are hydrophobic
But the phosphate group is hydrophilic
When drawing a phospholipid you draw a…head and…tails
Phosphate
Fatty acid
During the condensation of a triglyceride (process of it being formed)…molecules of water are released and …ester bonds are formed
3
During the condensation of a triglyceride…molecules of water are released
3
During the condensation of a triglyceride…ester bonds are formed
3
During the…of a triglyceride 3 molecules of water are released and 3 ester bonds are formed
Condensation
When hydrolysed triglyceride is split by the addition of …water molecules
3
Phospholipids form…in water where they position themselves so that the phosphate heads are as close to the water as possible and the fatty acid tails are as far from the water as possible
Bilayers
Bilayer meaning
Where when placed in water phospholipids position themselves so that the phosphate heads are as close to the water as possible and the fatty acid tails are as far from the water as possible
(The arrangement of phospholipids in water)
Triglycerides are made up of hydrogen, carbon and oxygen whereas phospholipids are made up of hydrogen, carbon, oxygen and also…
Phosphorus
Triglycerides are hydrophobic whereas phospholipids are both hydrophobic and…
Hydrophilic
(The phosphate group (head) is hydrophilic but the fatty acids (tails) are hydrophobic)
Phospholipids contain a …whereas triglycerides don’t
Phosphate group
Triglycerides are made up of…fatty acids whereas phospholipids are made up of…fatty acids
3
2
Both triglycerides and phospholipids have….(type of bond) bonds
Ester
(Between glycerol and fatty acid)
Both triglycerides and phospholipids can have saturated or unsaturated…
Fatty acids
(The R group (long hydrocarbon chain) of fatty acids can be either saturated or unsaturated)
In animal cells there is…embedded in the cell membrane to add stability
Cholesterol
In animal cells there is cholesterol embedded in the cell membrane to add…
Stability
Only animal cells have cholesterol embedded in the cell membrane to provide stability but not plant cells as plant cells also have a …
Cell wall
You describe precipitates as c…but emulsions as m…
Cloudy
Milky
You describe …as cloudy but…as milky
Precipitates
Emulsions
Which out of a precipitate and emulsion can be filtered
Precipitate (where there’s a solid in a liquid)
(Emulsion is where there are tiny liquid droplets in a liquid)
Method for emulsion test
1) Mix sample with 5cm cubed alcohol in a test tube
2) Shake thoroughly
3) Add 5cm cubed cold water and shake gently
4) Milky white emulsion formed indicates presence of lipid
In the emulsion test which do you add first out of water and alcohol
Alcohol
(Add sample to test tube with 5cm cubed of alcohol and shake thoroughly then add 5cm cubed of water and shake gently)
In the emulsion test which do you do first, shake gently or shake thoroughly
Thoroughly
(After adding sample and 5cm cubed of alcohol to test tube. Then add 5cm cubed water and shake gently)
First stage of emulsion test
Add sample and 5cm cubed of alcohol to test tube and shake thoroughly
(Then add 5cm cubed water and shake gently and if lipid is present a milky white colour should form)
In the emulsion test if lipid is present then a …emulsion should form
Milky white
For the emulsion test as a control you should…
Repeat the whole procedure using just water and the solution should remain clear
For the emulsion test as a control you should…
Repeat the whole procedure using just water and the solution should remain clear
Why triglycerides are used as energy storage molecules
They contain lots of chemical energy (triglycerides are composed of long hydrocarbon chains in the fatty acid with lots of chemical bonds between carbon and hydrogen atoms and these bonds hold a large amount of energy)
They’re insoluble in water (
Name of tissue (body fat) that triglycerides are stored in
Adipose
True or false, plasma membrane and cell membrane are the same thing
True
The centre of the bilayer in the cell membrane is… so water soluble substances can’t easily pass through it
Hydrophobic
(As all the hydrophobic fatty acid tails from the phospholipids are on the inside)
What is the emulsion test on a food sample testing for
Presence of Lipids (fats)
What is the emulsion test on a food sample testing for
Presence of Lipids (fats)
True or false, both triglycerides and phospholipids are insoluble in water
True
Explain why phospholipids can form a bilayer but triglycerides can’t (3 marks)
Phospholipids are both hydrophobic and hydrophilic so phosphate group attracts water to either side of the bilayer but triglycerides are only hydrophobic
