Carbohydrates part 1 Flashcards
- what are most carbohydrates
most carbohydrates (as well as proteins and nucleic acids) are polymers.
- define a polymer
polymers are large, complex molecules composed of long chains monomers joined together
- what are monomers
monomers are small, molecular units
- examples of monomers
Monosaccharides, amino acids and nucleotides
- what are carbohydrates made from
carbohydrates are made from monosacchrides
- what elements do all carbohydrates contain
all carbohydrates contain the elements C H and O
- examples of monosaccharides
glucose, fructose and galactose
- define glucose
glucose is a hexose sugar- a monosaccharide with six carbon atoms in each molecule
- what are the two types of glucose
alpha and beta- theyre are isomers
- what are isomers
molecules with the same molecular formula as each other, but with the atoms connected in a different way
- draw an alpha-glucose molecule
- what joins monosaccharides together
condensation reactions join monosaccharides together
- explain a condensation reaction
a condensation reacction is when two molecules join together with the formation of a new chemical bond, and a water molecule is released when the bond is formed
- what happens after the monosaccharides are joined together
a glycosidic bond forms between the two monosaccharide as a molecule of water is released
- what happens when 2 monosacchrides join
a dissacchride is formed
- what happens when 2 alpha-glucose molecules are joined
two alpha-glucose molecules are joined together by a glycosidic bond to form maltose
- define sucrose and explain how it is formed
sucrose is a disaccharide
formed from a condensation reaction between an alpha glucose molecule and a fructose molecule
- define lactose and explain how it is formed
lactose is another disaccharide formed from an Alpha-glucose molecule and a Beta galactose molecule
- what breaks polymers into monomers
hydrolysis reactions break polymers down into monomers
- explain a hydrolysis reaction
a hydrolysis reaction breaks the chemical bond between monomers using water molecule. its basically the opposite of a condensation reaction
- what is a general term for monosaccharides and disaccharides
sugar
- what can call sugars be classified as
reducing or non-reducing
- what does reducing sugars include
reducing sugars include all monosaccharides (e.g. glucose) and some disaccharides (e.g. maltose and lactose)
- steps to testing sugars
you add blue benedicts reagent to a sample and heat it in a water bath thats been brought to the boil
if the test’s positive it will form a coloured precipitate ( solid particles suspended in the solution the colour of the precipitate changes from: blue —) green —) yellow —) orange —) brick red the higher the concentration of reducing sugar, the further the colour change goes
- how can we use the concentration of reducing sugars
you can use this to compare the amount of reducing sugar in different solutions.
A more accurate way of doing this is to filter the solution and weigh the precipitate
- what does it mean if the benedicts test for sugars is negative
there could still be a non- reducing sugar present
- how do you test for non-reducing sugars
to test for non- reducing sugars like sucrose, first you have to break them down into monosaccharides
- how do you break non-reducing sugars into monosaccharides
you do this by getting a new sample of the test solution, adding dilute hydrochloric acid, and carefully heating it in a water bath that’s been brought to the boil
you then neutralize it with sodium hydrogen carbonate. then just carry out the benedicts test as you would for reducing sugar if the test is negative the solution will stay blue which means it doesn't contain any sugar
- How do we make sure all the sugar reacts
always use an excess of benedicts solution
