Carbohydrates Flashcards
What are polymers?
Large, complex molecules composed of long chains of monomers joined together.
What are monomers?
Monomers are small, basic molecular units.
What are some examples of monomers?
monosaccharides, amino acids and nucleotides
What elements do all carbohydrates contain?
C, H and O
What are the monosaccharides that carbohydrates and made from called?
glucose, fructose, galactose
How many carbons does glucose contain?
6 - it is a hexose sugar
What is the diffrence between alpha glucose and beta glucose?
they have a diffrent arrangement of atoms. they have the H and OH, group reversed. H on top for alpha on rightside, OH on top for beta on the riightside.
What is a condensation reaction?
two molecules join together with the formation of a new chemical bond, and a water molecule is realeased.
How are Monosaccharides join together?
condensation reaction
What is the bond called between to monosaccharides?
Glycosidic bond
What is formed when two monosaccharides join together?
A disaccharide
What do two molecules of alpha glucose form when joined up?
maltose
What does fructose and glucose form when joined ?
Sucrose
What does glucose and galactose form when joined?
Lactose
How are polymers broken back down to monomers?
By a hydrolysis reaction
What is a hydrolysis reaction?
Hydrolysis reaction breaks the chemical bond between monomers using a water molecule.
What test is used for sugars?
Benedicts reagent
What sugars are reducing sugars?
All monosaccharides and some disaccharides
What do you do after adding benedicts reagent to a sample?
heat it in a water bath that been brought to the boil.
What would happen if the test is positive for a reducing sugar?
the sample will turn coloured brick red or orange
If the result for reducing sugars is negative what can you do?
a test for non reducing sugars
How do you break up the sample into monosaccharides?
add dilute HCl and carefully heat it in a water bath thats been brought to boil. you can nuetralise it with sodium hydrogencarbonate.
What do you do after you break up the monosaccharides in a non reducing sugar test?
carry out benedicts test normally
How would you do if the test is postive for a non reducing sugar?
it will form a coloured precipitate, if the test is negative the solution will stay blue which means it does not contain a sugar( either reducing or non reducing).
How is a polysaccharide formed?
it is formed when more than two monosccharides are joined together by a condensation reaction
Where do cell get energy from?
glucose
What do plants store excess glucose as?
starch (when a plant needs more glucose for energy, it breaks down starch to release the glucose)
What are the two polysaccharides of alpha glucose that make up starch called?
amylose and amylopetin
What is amylose?
a long, unbranched chain of alpha glucose. the angles of the glycosidic bonds give it a coiled structure, almost like a cylinder. this makes it compact so its really good for storage because you can fit more in to a small space.
What is amylopectin?
a long, branched chain of alpha glucose. its side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily. this means that glucose can be released quickly.
What is the test for starch?
Iodide
What is a postive test for starch with iodide?
blue/black colour
What do animals store execess glucose as?
glycogen
What is the stucture of glucogen?
loads of branchs means that stored glucose can be released quickly, which is important for energy release in animals. it is also compact molecule so its a good storage molecule
What is cellouse made up of?
long, unbranched chains of beta glucose
What do beta molecules form when they bond?
staight cellouse chains
What happens when the cellulose chains are linked together by hydrogen what do they provide?
they form strong fibers called microfibrils. the strong fibres mean cellulose provide structural support for cells
