biological molecules

what are carbohydrates used for?

energy

what elements do carbohydrates contain?

carbon, hydrogen, oxygen

what are the three main groups of carbohydrates?

monosaccharides, disaccharides and polysaccharides

what are monosaccharides?

sweet tasting, soluble, crystalline sugars

give three examples of monosaccharides

fructose, glucose, galactose

what are disaccharides?

two monosaccharides joined together by a glycosidic bond formed in a condensation reaction (water is lost)

what are polysaccharides?

polymers containing many monosaccharides linked by glycosidic bonds formed in condensation reactions (water is lost)

what are polysaccharides used for?

energy store

name the main polysaccharides in plants and animals

starch and cellulose (plants), glycogen (animals0

is glucose a monomer?

yes

what is the formula for glucose?

C₆H₁₂O₆

what kind of sugar is glucose?

hexose sugar (6 carbons)

true or false: glucose is insoluble

false

what is glucose produced during?

photosynthesis

where is glucose found?

sweet tasting food, fruits, vegetables

what is glucose used during?

respiration

what is the food test for glucose?

Benedict’s and heat

give the positive result for Benedict’s and heat test

low: green, yellow, orange, red :high

give the negative result for Benedict’s and heat test

stays blue

how do you work safely when performing the Benedict’s and heat test?

wear goggles, use a waterbath

how does tooth decay occur?

lots of sugar in our diet can lead to tooth decay. Bacteria feed on the sugar and break it down, creating acid, which dissolves the tooth enamel. Once through the tooth enamel, the acid breaks down the soft dentine, creating a cavity

what is starch?

the store of glucose in plants

how does the structure of starch aid its function?

doesn’t affect osmosis

branched so it is easily hydrolysed (broken down)

inert (not reactive)

compact

insoluble

how does starch get broken down?

starch→(amylase) maltose→(maltase) glucose

what is the test for starch?

iodine

give the positive test result for starch

black

give the negative result for starch

stays orange/brown

what is maltose formed from

two glucose molecules

what is sucrose formed from

glucose and fructose

what is lactose formed from

glucose and galactose

why are some people lactose intolerant?

they don’t have the enzyme needed to break down lactose

where is cellulose found

cell wall in plants

what does cellulose provide in our diet?

fibre

why isn’t cellulose broken down in humans?

don’t have the enzyme cellulase

which parts of a plant cell can be digested

all of it except for the cell wall

why is cellulose important in our diets?

gives our muscles something to push against, prevents constipation

is cellulose present in faeces?

yes