carbohydrates Flashcards
what atoms are carbohydrates made out of
carbon, hydrogen, oxygen atoms
what is the H:O ratio in carbohydrate molecules
2:1
properties of monosaccharides
simplest form of carbohydrates, soluble in water, sweet
examples:
glucose (fruit)
fructose (fruit)
galactose (dairy products)
properties of disaccharides
formed by condensation of 2 molecules of monosaccharides, soluble in water, sweet
examples:
maltose (malt)
sucrose (sugarcane)
lactose (milk)
properties of polysaccharides
formed by condensation of 3 or more monosaccharide molecules, insoluble in water, tasteless
examples:
starch (cereals)
glycogen (liver)
cellulose (vegetables)
can disaccharides and polysaccharides be absorbed directly
no, they cannot be directly absorbed and need to be broken down into monosaccharides for digestion
what milk can lactose be found in
cow’s milk only
where can glycogen be found in the human body
liver and muscles
what is cellulose used for
structural support in plant cell walls
what is starch used for
major storage form of carbohydrates in plants, major energy source in most diets
what is condensation
a reaction where a bond is formed and water is produced (energy is absorbed overall and energy is stored in the bond)
what is hydrolysis
a reaction where a bond is broken using water and energy is released overall
monosaccharide + monosaccharide
disaccharide + water
what is the bond between 2 monosaccharides called
glycosidic bond
glucose + glucose
maltose + water
glucose + fructose
sucrose + water
glucose + galactose
lactose + water
functions of carbohydrates
- energy source (as glucose is oxidised in body cells and releases chemical energy during respiration to provide energy)
- storage material (starch is stored in plants while glycogen is stored in the liver / muscles of animals)
- structural material (cellulose is the main component of cell walls)
what are excess carbohydrates converted into
glycogen
why can’t we digest cellulose?
our body doesn’t have the enzymes to break it down
why do we use polysaccharides for storage
their branched structure allows for them to be stored in a more compact way, and they are also insoluble in water
why is cellulose used to form cell walls
as it is composed of long chains of glucose molecules with no branching, with hydrogen bonds forming between adjacent chains, stabilising the molecule. this structure provides high tensile strength so that plant cell walls are strong enough to support plant cells
why is carbohydrates the primary energy source
as it can be broken down over time and therefore can provide energy readily
