1.1 carbohydrates

simplest carbohydrates. Formula is (CH20)n. Common hexose monosaccharides (with 6 carbons) are glucose, galactose and fructose. Ribose- monosaccharides but Pentose sugar with 5 carbons so c5h10O5. Found in RNA

molecules with same chemical formula but different arrangement.

C6H12O6. Main source of energy for respiration. Used for building larger carbohydrates. Small so easily transported in and out of cells through carrier protein. Soluble so easily transported. Not very reactive so enzymes control rate of respiration/ so stable energy release Alpha glucose the H is above the Oh but in beta glucose the H is below the OH How to remember structure- in Alpha the OH are both at the bottom.

formed by joining two monosaccharides in condensation reaction forming glycosidic bonds and releasing water.

maltose

sucrose

lactose

go around the molecule, stating from right, clockwise by numbering them (e.g. maltose has 6 carbons, so the glycosidic bond is between carbon 1 and carbon 4 hence 1.4 glycosidic bond)

dding many monosaccharides in a chain through condensation reaction. Hydrolysis reaction used to break down into monosaccharides. Large and insoluble so don’t impact water potential. Compact so lots of energy can be stored. Easily broken down in hydrolysis so energy is easily released. Glycosidic bonds are easily broken so glucose can be easily released for respiration. Physically and chemically inactive so don’t interfere with other cell functions. Can be structural or storage.

Made of two polysaccharides- amylose and amylopectin Amylose- long chain of alpha glucose joined by 1,4 glycosidic bonds. Coiled helix shape which is more compact so more glucose is stored. Has only two ends which means amylose is broken down slowly as the enzyme amylase can only break down from two sides to get energy for respiration- not very efficient Amylopectin- long chain of alpha glucose joined by 1,4 and few 1,6 glycosidic bonds. This creates more branching so there are more accessible ends so quicker release of alpha glucose for respiration/ starch easily broken down. Branched structure ,eams larger surface area for rapid hydrolysis back to glucose

stored in photosynthetic cells in leaves as it has a large supply of energy and storage cells such as seeds. Stored in organelles called amyloplasts.Very compact - helical to release more alpha glucose and insoluble so water balance is maintained. When cells need glucose, enzymes are used to break glycosidic bonds (hydrolysis reaction which needs water).large molecules so cannot cross cell membrane. Rich in glucose . Branched- rapidly hydrolysed into glucose

only in animals, found in liver and muscle cells. Highly branched. Function is insoluble storage of glucose. Many alpha glucose chains joined by 1,4 and 1,6 glycosidic bonds ( more 1,6 compared to amylopectin- so more branches). Even more accessible ends so more alpha glucose is released. Glycogen can be rapidly hydrolysed. Important for animals as they have high rate of respiration so glycogen can be quickly converted into glucose for respiration. Insoluble ( doesn’t disrupt water balance) and large molecules so can’t diffuse out of cells.

Add acid and boil . Neutralise with alkali. Add Benedict’s and add to water bath. blue-> Red precipitate will form

turn food sample into solution(crush and add water). add benedict’s solution and put in water bath at 80 degrees. blue-> brick red. the stronger the brick red the higher concentration of reducing sugar

make different glucose concentration solutions. in each test tube add benedict’s solution. heat in water bath then allow to cool and a white precipitate solid settle at the bottom. use a colorimeter with orange filter to measure OD/ absorbance. as concentration increases absorbance decreases because less light passes through, as glucose is a reducing sugar so copper 2+ (blue) ions in benedicts turn into cu+ (clear). if clear there is less absorption

Do reducing tests first. If negative then add acid, boil, add alkali, add Benedict’s, water bath. Will go brick red

structural role found in plant cell walls to stop plant cell from bursting but rather to stay turgid for extra support. Made of beta glucose chains with 1,4 glycosidic bonds. Every other beta glucose in the chain is flipped outside down to form glycosidic bonds which leads to a long straight chain. many chains can be parallel to other chains. OH (hydroxyl groups) are therefore near each other so hydrogen bonds form, which leads to cross linking, many hydrogen bonds make cellulose very strong to form microfibrils, which wraps around plant cells which gives extra strength. Permeable to allow water through.

maltose- reducing amylose- non reducing fructose- reducing

CnH2nO2

CnH2n-2O2

no

2 glucose - water

high carbon/hydrogen content has no water