carbohydrates 3.1.2 Flashcards
3 main functions of carbohydrates
short term energy storage
long term energy storage
structural components
name 3 polysaccharides
glycogen starch and cellulose
which two polysaccharides can be digested and used for energy
starch and glycogen
what is the glycemic index
measurement of blood glucose level increase from consumption of carbohydrates
what are the 3 types of monosaccharides
3 carbons - triose
5 carbons - pentose
6 carbons - hexose
two isomers of glucose
alpha and beta
define an isomer
molecules that have the same molecular formula but have a different arrangement of atoms
what type of monosaccharide is glucose
hexose
what’s the difference between alpha and beta glucose
alpha - OH is below ring
beta - OH is above ring
2 other hexoses
fructose
galactose
what is a disaccharide
double sugar composed of pairs of monosaccharide units joined by a glycosidic bond. (joined by a condensation reaction)
what is maltose made of
two alpha glucoses
what is sucrose made of
glucose and fructose
what is lactose made of
glucose and galactose
define hydrolysis
chemical insertion of a molecule of water to split a disaccharide into its constituent monosaccharides
define reducing sugar
sugars that can donate an electron to another molecule
reducing sugars test
1) benedict’s reagent
2) shake, and heat for a few minutes at 95°c in a water bath
3) a precipitate (green,yellow,orange,red) indicates reducing sugar
is benedict’s test quantative or qualitative
qualitative
example of a non reducing sugar
sucrose
non reducing sugars test
1) first test for reducing, if negative continue
2) dilute hydrochloric acid
boil hydrolyse the glycosidic bond
3) add sodium hydrogen carbonate solution to neutralise
4) re test solution with benedict’s reagent
5) if non reducing sugar is present, solution will now change colour
what is a polysaccharide
formed from 3 or more monosaccharides joined with glycosidic bonds
what are the two types of polysaccharide
storage
structural
storage polysaccharides
starch
glycogen
example of a structural polysaccharide
cellulose
starch test
stains deep blue with iodine solution
function of glycogen
glucose storage molecule in ANIMALS
what glucose is glycogen made of
alpha
types of glycosidic bonds in glycogen
1,4 and 1,6
4 features of glycogen
- very compact
- very branched
- insoluble
- large molecule
benefit of glycogen being insoluble
glycogen does not draw water into cell by osmosis
benefit of glycogen being a large molecule
cannot diffuse out of a cell
function of cellulose
major part of the cell wall in plant cells
what glucose is cellulose is made of
beta
what type of glycosidic bond is in cellulose
1,4
3 features of cellulose
- unbranched
- strength
- permeable to molecules
why is cellulose extremely strong
hydrogen bonds form between layers of chains forming microfibrils
benefit of strength of cellulose
allows cellulose cell wall to carry out its functions
benefit of cellulose being permeable to water
water enters and due to strength of cellulose cell wall can resist outwards pressure.
water in cell makes it turgid - gives plant upright structure
function of starch
storage of glucose in PLANT cells
what is starch made of
amylose and amylopectin
what glycosidic bonds does amylopectin have
1,6
is amylopectin branched
yes
what glucose is starch made of
alpha glucose
what glycosidic bonds does starch have
1,6 and 1,4
structure of amylose
twisted into a complex helix structure hydrogen bonds between glucose molecules
is amylose branched or unbranched
unbranched
4 features of starch
- compact shape
- insoluble
- easily hydrolysed
- branched form
benefit of starch having a compact shape
takes up little space
benefit of starch being insoluble
does not affect water potential, so water is not drawn into the cell by osmosis
benefit of starch having a branched form
has many ends that enzymes can act on simultaneously meaning glucose monomers are rapidly released
