Unit 1 - Monomers+Polymers Flashcards
Definition of a monomer?
Monomers are the small soluble molecules from which larger molecules are made.
Definition of a polymer?
Polymers are molecules made from a large number of similar monomers joined together.
What is a condensation reaction?
A reaction that joins 2 molecules together with the formation of a chemical bond and involves the release of a water molecule.
What is a hydrolysis reaction?
A reaction that breaks a chemical bond between 2 molecules and involves the use of a water molecule.
What are monosaccharides and provide 3 examples?
Monosaccharides are the monomers from which larger carbohydrates are made. Glucose, galactose and fructose are common monosaccharides. They all have the same formula of C6H12O6
What bond does a condensation reaction between 2 monosaccharides form?
A glycosidic bond.
What are the 2 isomers of glucose?
Alpha-glucose and beta-glucose
Structure of alpha-glucose?
Structure of beta-glucose?
How are disaccharides formed and what is their formula?
They’re formed by the condensation of 2 monosaccharides. They all have the same formula of C12H22011 (C6H12O6+C6H12O6) (the removal of a H2O molecule)
What monosaccharides is maltose made from?
Glucose + glucose
What monosaccharides is lactose made from?
Galactose + Glucose
What monosaccharides is sucrose made from?
Glucose + Fructose
Equation for the formation of a disaccharide?
C6H12O6 + C6H12O6 = C12H22O11 + H2O
Why does a condensation reaction between 2 monosaccharides form a 1,4 glycosidic bond?
The reaction occurs between the OH groups on carbon 4 of one monosaccharide and carbon 1 on the other monosaccharide. This creates a 1,4 glycosidic bond.
Equation for the hydrolysis of disaccharides?
C12H22O11 + H2O = C6H12O6 + C6H12O6
3 examples of polysaccharides?
Glycogen + starch = storage
Cellulose = structural
What is starch made from? And what is it used for?
It is a polysaccharide of alpha glucose. And is the storage carbohydrate in plants.
What are the properties of starch and how does this relate to its function? (6marks)
Insoluble - does not affect osmosis/does not diffuse across the cell membrane and out of cells.
Coiled into a helix - compact so a lot can fit into a small space.
1,4 and 1,6 glycosidic bonds - allows branching to occur.
Branched - provides many ends for faster hydrolysis by enzymes to form alpha-glucose for use in respiration.
What are the 2 parts of starch and their functions?
Amylose - helix structure + 1,4 glycosidic bonds.
Amylopectin - 1,4 glycosidic bonds + 1,6 glycosidic bonds which allows branching to occur.
What is glycogen a polymer of? And what is it used for?
It is a polymer of alpha glucose. It is the storage carbohydrate in animals.
How does glycogen differ from starch? How do these features benefit glycogen?
It has shorter chains.
It is more highly branched.
It has a larger surface area.
These features lead to glycogen being more readily hydrolysed into glucose for respiration. This is more important in animals as they move more than plants.
How does the structure of starch relate to its function? (6 marks)
Insoluble - does not affect osmosis/does not diffuse across the cell membrane and out of cells.
Coiled into a helix - compact so a lot can fit into a small space.
1,4 + 1,6 glycosidic bonds - allows branching to occur.
Very highly branched - provides many ends for faster hydrolysis by enzymes to form alpha-glucose for use in respiration.
What is cellulose a polymer of?
Beta-glucose
How does beta-glucose differ from alpha-glucose?
The position of the H and Oh groups on carbon 1 are inverted.
What’s special about beta-glucose molecules in condensation reactions?
Every other beta-glucose molecule flips 180degrees to allow OH groups on carbon 1 and 4 to be adjacent to each other to form a glycosidic bond.
How is a cellulose cell wall formed?
Several chains of cellulose are joined together in layers; these chains are held together by the formation of hydrogen bonds formed between OH groups. Hundreds of these chains are then held together by hydrogen bonds to form microfibrils. Microfibrils form hydrogen bonds between other microfibrils and together to form a cellulose fibre. Cellulose fibres are woven to form a cellulose cell wall.
How does the structure of cellulose relate to its function?
Only 1,4 glycosidic bonds present-allows formation of long, straight, unbranched chains of beta-glucose.
Long, straight, unbranched chains of beta-glucose-allows formation of many hydrogen bonds so microfibrils are created.
Many microfibrils and cellulose fibres and many hydrogen bonds-provides strength to the cell wall.
What is the Benedict’s test for reducing sugars?
1) Add Benedict’s solution to sample and heat to 95degrees.
2) A colour change from blue to green/yellow/orange/red precipitate indicates the presence of reducing sugar.
How could you use this test to get a quantitative measurement?
1) Filter off the precipitate
2) Dry and weigh it
Benedict’s test for non-reducing sugars?
1) Add Benedict’s solution to sample and heat to 95degrees and if there is no change in the Benedict’s test for reducing sugar, boil a fresh sample with dilute HCl acid for a few mins to hydrolyse the glycosidic bonds.
2) Neutralise, by adding solid sodium hydrogen carbonate.
3) Then add Benedict’s reagent and heat to 95degrees.
4) A colour change from blue to a red precipitate.
What is the test for starch?
Iodine solution test.
1) Add iodine in potassium iodide solution to your sample.
2) A colour change from orange to blue-black indicates the presence of starch.
