12.1 - Carbs & Lipids Flashcards
What are monomers?
What are polymers?
Monomers are small, identical or similar molecules which can be joined together (condensed) to make larger molecules called polymers.
A large molecule made from the joining (by chemical bonds) of 3 or more similar or identical monomer molecules.
Formed by condensation reaction.
What is a condensation reaction?
What is a hydrolysis reaction?
A condensation reaction involves the formation of a chemical bond, removing a water molecule. Monomers -> polymers.
A hydrolysis reaction involves the breaking of a chemical bond, using a water molecule. Polymers -> Monomers.
What elements are found in all carbohydrates?
What is the ratio of H:O?
What are carbohydrate monomers called? + E.g
What are carbohydrate dimers called? + E.g
What are carbohydrate polymers called? + E.g
What are isomers?
C, H and O.
2:1.
Monosaccharides. (glucose, galactose, fructose)
Disaccharides. (maltose, lactose, sucrose)
Polysaccharides. (starch, glycogen, cellulose)
Molecules with the same molecular formula but a different arrangement of atoms.
How is a disaccharide formed?
What do Glucose + Glucose form? What enzyme speeds the hydrolysis of it?
What do Glucose + Galactose form? What enzyme speeds the hydrolysis of it?
What do Glucose + Fructose form? What enzyme speeds the hydrolysis of it?
Two monosaccharides can join together in a condensation reaction. This produces (uses) a water molecule. A glycosidic bond is formed between them.
Glucose + Glucose = Maltose. Hydrolysed by Maltase.
Glucose + Galactose = Lactose. Hydrolysed by Lactase.
Glucose + Fructose = Sucrose. Hydrolysed by Sucrase.
DRAW
ALPHA GLUCOSE, (penguin)
BETA GLUCOSE, (hieroglyphic)
GALACTOSE, (raver)
FRUCTOSE. (witch’s hat)
alpha - OHs at bottom
beta - one OH at top, other at bottom
galactose - both OH at top
fructose - o at top, 2 ch2oh groups
Give the structures and features of starch. (4)
MADE OF…
1) Helical/spiral - so compact, tightly packed, can fit lots into a small space.
2) Insoluble - so no osmotic effect, doesn’t affect WP + doesn’t leave cell.
3) Large molecule/long chains - doesn’t leave cell + large no. of glucose units.
4) Branched chains - Increased SA, rapid hydrolysis to remove glucose for respiration.
MADE OF ALPHA GLUCOSE.
Give the structures and features of glycogen.
MADE OF…
What is the difference between starch and glycogen? Glycogen has shorter…because…
Where are they found?
1) Insoluble - so no osmotic effect, doesn’t affect WP + doesn’t leave cell.
2) Large molecule/long chains - doesn’t leave cell + large no. of glucose units.
3) Branched chains - Increased SA, rapid hydrolysis to remove glucose for respiration.
MADE OF ALPHA GLUCOSE.
Glycogen has shorter chains = more rapidly hydrolysed to be used in respiration, animals require glycogen to be hydrolysed faster.
FOUND IN SKELETAL AND CARDIAC MUSCLES IN ANIMALS.
The structure of cellulose is related to its function in plant cell walls. Explain how. (4)
MADE OF…
1) Long straight unbranched chains of Beta Glucose
2) Joined together by many weak hydrogen bonds
3) Form micro/macrofibrils
4) Provide strength/support
MADE OF BETA GLUCOSE.
Hydrogen bonds are important in cellulose molecules. Explain why. (3)
1) Hydrogen bonds hold chains together / form cross links between chains of cellulose molecules
2) They provide strength + rigidity to cellulose/cell wall
3) Weak hydrogen bonds provide strength in large numbers.
Describe the test for reducing sugars (glucose, galactose, fructose, lactose, maltose.) (3)
1) Add Benedict’s solution/reagant
2) Heat to 95.C
3) Red/orange/yellow/green precipitate (depending on concentration)
Describe the test for non-reducing sugars (sucrose) (5)
1) Complete Benedict’s test for R.S and observe a negative result/stays blue.
2) Add acid and heat to 95.C
3) Neutralise with alkali
4) Add Benedict’s reagant and heat to 95.C
5) Red precipitate
Solutions are…
A precipitate is..
TRANSPARENT
a solid suspended in a liquid.
What is the test for starch?
1) Add potassium iodide (KI) solution
2) Solution turns blue/black colour if starch is present.
What is a quantitive test to measure the concentration of sugar in a solution?
How do you standardise this method? (3)
You can use a colorimeter, it measures the intensity of light passing through a solution.
Larger concentration of reducing sugar =
reduced transmission (au) / more absorbance
1) Samples should be shaken before testing.
2) Zero the colorimeter before use (with a control e/g water)
3) Use same volume for each reading.
Describe how you would produce a calibration curve for a reducing sugar of unknown concentration and use it to obtain results. (5)
1) Make up several known conentrations of a reducing sugar (e.g glucose).
2) Carry out the Benedict’s test on each sample.
3) Use a colorimeter to measure the colour intensity of each solution (absorbance/transmission) and plot a calibration curve.
4) Known concentration on X axis and Absorbance/transmission on Y axis.
5) Find the concentration of the unknown sample using the calibration curve.
Give two functions of lipids.
1) Conduct heat slowly, good thermal and electrical insulators.
2) Stored around delicate organs e.g kidney to protect them.
Describe the test for lipids. (2)
1) Mix sample with ethanol, then add water and shake.
2) Cloudy white emulsion.
Some seeds contain lipids. Describe how you could use the emulsion test to test for lipids. (4)
1) Crush/grind the seeds.
2) With ethanol to dissolve the lipid.
3) Then add water then shake.
4) Forms a white emulsion.
What is a triglyceride made up of and how is it formed?
IT IS NOT A…
Made from one molecule of glycerol bonded to three fatty acids joined by ester bonds.
(NOT A POLYMER - not made of similar/same monomers.)
Formed by 3 condensation reactions, 3 ester bonds are formed and 3 water molecules are released.
What is an unsaturated fatty acid?
Double bond(s)
Between carbon atoms in the hydrocarbon chain.
Why are triglycerides good stores of energy and good source of water?
Energy - they have a low mass to energy ratio.
Water - storing them does not affect the water potential because they’re insoluble in water, they have a high H:O ratio, good source of water when broken down.
What is a phospholipid made of and what is the main difference with a triglyceride?
Made up of two fatty acids, glycerol and a phosphate group. (while triglycerides have 3 FAs)
How does the structure of a phospholipid allow it to form a bilayer in water?
The head and tails… (charges + properties)
They face… (direction)
The phosphate group head (PO4 3-) has a negative charge (polar) whereas the fatty acid tails have no charge, they are non-polar.
This makes the phospho-glycerol head hydrophilic (attracts water - soluble) and the FA tails hydrophobic (repels water - insoluble)
The hydrophobic tails face each other/away from the water (arranged in the middle)
The hydrophilic heads face the water.
Compare and contrast the structure and properties of triglycerides and phospholipids. (8)
1) Both contain ester bonds
2) Both contain glycerol
3) Fatty acids on both can be saturated or unsaturated
4) Both are insoluble in water
5) Both contain C,H and O but phospholipids also contain P.
6) Triglycerides have 3 FAs, while phospholipids have 2 FAs and a phosphate group.
7) Triglycerides are hydrophobic/non-polar while phospholipids have a hydrophobic and hydrophilic region.
8) Phospholipids form a bilayer/micelle but triglycerides don’t.
Describe the test for amylase. (2)
1) Add Biuret’s reagant and becomes violet/lilac
2) Add starch (leave for a time), then test for the absence of starch
How can you measure the quantity of reducing sugar in a solution w/o colorimeter?
1) Filter and dry the precipitate
2) Find mass
