Protein And Carbs Flashcards
What are carbs?
Molecules that only contain the elements carbon, hydrogen and oxygen.
Examples of monosaccharides
Glucose, fructose and ribose.
What happens when two monosaccharides link together?
They form a disaccharide, for example lactose and sucrose.
What happens when 2 or more monosaccharides link together?
They form a polymer called a polysaccharide. For example glycogen, cellulose and starch.
How many carbons is glucose composed of?
Six and therefore is called a heroes monosaccharide.
Properties of glucose molecules.
Polar, soluble in water.
What type of bond is a glycosidic bond?
Covalent.
What happens during a condensation reaction?
The reaction is called a condensation reaction because a molecule is formed as one of the products of the reaction.
What do Pentose monosaccharides contain?
5 carbon atoms.
What is amylopectin made of?
Amylopectin is also made by 1-4 glycosidic bonds between alpha glucose molecules.
What does glycogen form?
Glycogen forms more branches than amylopectin, which means it is more compact and less space is needed for it to be stored.
Key properties of amylopectin and glycogen.
Insoluble, branched and compact. These properties mean they are ideally suited to the store age roles that that carry out.
Different between reducing and non-reducing sugars?
Reducing sugars have the ability to be oxidised (loss of electrons), while non-reducing sugars have the ability to be reduced (gaining of electrons).
What is glucose stored as?
Starch until it’s needed for respiration.
Hydrolysis reaction in starch/glucose.
To release glucose for respiration, starch or glycogen undergo hydrolysis reactions, requiring the addition of water molecules. The reactions are catalysed by enzymes.
Why can’t beta glucose molecules join together in the same way that alpha glucose molecules can?
The hydroxyl groups on carbon 1 and carbon 4 of the two glucose molecules are too far from each other to react.
The only way that beta glucoses molecules can join together can join together and form a polymer is if alternate beta glucose molecules are turned upside down.
What do cellulose molecules make when forming microfibrils?
Hydrogen bonds.
Properties of micro/macro fibrils.
Strong
insoluble
Used to make cell walls
Reducing sugars test.
- Place the sample to be tested in a boiling tube. If it is not in liquid form, grind it up or blend it in water.
- Add an equal volume of Benedict’s reagent.
- Heat the mixture gently in a boiling water bath for 5 minutes.
Positive result = brick red precipitate is formed.
Non-reducing sugars test.
- Place the sample to be tested in a boiling tube. If it is not in liquid form, grind it up or blend it in water.
- Add an equal volume of Benedict’s reagent.
- Heat the mixture gently in a boiling water bath for 5 minutes.
Non-reducing sugars don’t react with Benedict’s solution.
Solution remains blue if negative.
If sucrose is first boiled with dilute hydrochloric acid it will then give a positive result when warmed with Benedict’s solution. This is because the sucrose has been hydrolysed by the acid to glucose and fructose, both reducing sugars.
Iodine test for starch.
- Add a few drops of iodine dissolved in potassium iodide solution to the sample and mix.
- If the solution changes colour from yellow/brown to purple/black then starch is present. If it stays the same, starch isn’t present.
What are peptides?
Polymers made up of amino acids. They contain carbon, hydrogen, oxygen and nitrogen.
Essential and non-essential amino acids.
All amino acids have the same basic structure. There are 20 different amino acids commonly found in cells. 5 are said to be non-essential as our body can make them from other amino acids. 9 are essential and can only be obtained from what we eat. 6 are said to be conditionally essential as they are only needed by infants and growing children.
Synthesis of peptides.
Amino acids join when the amine and carboxylic acid groups connected to the central carbon atoms react.
