1. Carbohydrates Flashcards
most carbohydrates are
polymers
carbohydrates are made from
monosaccharides
glucose is what kind of sugar
hexose sugar
two types of glucose
alpha glucose and beta glucose
difference between the 2 types of glucose
they are isomers (molecules of same molecular formula but with atoms connected in a different way)
a condensation reaction is when
2 molecules join with formation of new chemical bond and a water molecule is released
monosaccharides are joined together by
condensation reactions
what mond forms between monosaccharides
glycosidic
when 2 monosaccharides join a
disaccharide is formed
glucose + fructose
sucrose (disaccharide)
glucose + galactose
lactose (disaccharide)
glucose + glucose
maltose (disaccharide)
hydrolysis reactions
break polymers into their monomers. by addition of water
name of test for reducing sugars and non reducing sugars
benedicts test
reducing sugars are
all monosaccharides and some disaccharides (maltose and lactose)
how to test for reducing sugar
- add benedicts reagent (which is blue) to sample
- heat in a water bath thats been brought to the boil
- if the test is positive it will form a coloured precipiytate
change in colour precipitate for a reducing sugar
blue -> orange/brick red
what indicates the concentration of a reducing sugar
the colour change
blue -> green -> yellow -> orange -> brick red
(further along, higher concentration)
OR filter solution and weigh precipitate
test for non-reducing sugars (if result of reducing sugars is negative there could still be non-reducing sugar present)
first break down into monosaccahrides
- add dilute HCl to new sample
- carefully heat in water bath thats been brought to the boil
- neutralise it with sodium hydrogencarbonate
- . carry out benedicts test as you would for a reducing sugar.
- positive test = coloured precip. negative test = remains blue.
polysaccharide is
when more than 2 monosaccharides are joined
Starch
is the main energy storage in
plants
Starch
is a mixture of 2 polysaccharides
amylose
amylopectin
Starch
amylose is
a long unbranched chain of alpha glucose
angles of glycosidic bonds give it a coiled structure = makes it compact and therefore good for storage
Starch
amylopectin is
a long branched chain of alpha glucose
side branches allow enzymes that break it down to get to the glycosidic bonds easily = glucose can be released quickly
Starch
is insoluble in water so
it doesnt affect water potential = doesnt cause water to enter cells by osmosis which would make them swell.
= good for storage
how to test for starch
iodene test
add iodene dissolved in oitassium iodide solutiom to sample
starch present the sample changes from browny-orange colour to a dark blue-black colour
glycogen
is the main energy storage material in
animals
glycogen
pollysaccharide of which glucose
alphaglucose
glycogen
how is it similar to amylopectin
long and branched (more branched than amylopectin)
glycogen
how is it good for storage
very compact
glycogen
the fact it has lots of branches means
stored glucose can be released quickly (important for energy release in animals)
cellulose
is the major component of
cell walls in plants
cellulose
is made of
long unbranched chains of beta glucose
when bet glucose molecules bond they form straight cellulose chains
cellulose
cellulose chains are linked together by
Hydrogen bonds to form strong fibres called microfibrils
strong fibres means cellulose provides structural support for cells
