topic 1 - carbohydrates Flashcards
cgp (topic 1A) 2 - 5
what are polymers
large, complex molecules composed of long chains of monomers joined together
what are monomers
small basic molecular units
what are 3 examples of monomers
monosaccharides, amino acids and nucleotides
what elements do all carbohydrates contain
C,H, O
examples of monomers made from monosaccharides
glucose, fructose, galactose
what is glucose
a hexose sugar - a monosaccharide with six carbon atoms in each molecule
what are the two types of glucose
alpha α, beta β
what are isomers
molecules with the same molecular formula as each other but with the atoms connected in a different way
what is a condensation reaction
when two molecules join together with the formation of a new chemical bond and a water molecule is released when the bond is formed
what are monosaccharides joined together by
condensation reactions
how is a glycosidic bond formed
by a condensation reaction between an alcohol or amine of one molecule and the anomeric carbon of the sugar
how is a disaccharide formed
when two monosaccharides join together
what is sucrose
a disaccharide formed from a condensation reaction between a glucose molecule and a fructose molecule
what is lactose
a disaccharide formed from a glucose molecule and a galactose molecule
how can polymers be broken down into monomers
by hydrolysis reactions
what do hydrolysis reactions break
chemical bonds between monomers using a water molecule - basically the opposite of a condensation reaction
what is an example of a hydrolysis reaction
carbohydrates being broken down into their constituent monosaccharide by hydrolysis reactions
what is sugar a general term for
monosaccharides and disaccharides
how can all sugars be classified as
reducing or non reducing
what does the benedict’s test test for
sugars
how does the benedict’s test differ depending on
the type of sugar you are testing for
what do reducing sugars include
all monosaccharides and some disaccharides
how is a polysaccharide formed
when more than two monosaccharides are joined together by condensation reactions
what is the main energy storage material in plants
starch
how do plants store excess glucose
as starch
what do plants do when it needs more glucose for energy
it breaks down starch to release the glucose
what is starch a mixture of
two polysaccharides of alpha glucose (amylose and amylopectin)
what are the two polysaccharides of alpha glucose that form starch
amylose and amylopectin
what is amylose
the crystallizable form of starch, consisting of long, unbranched chains of α-glucose
what’s the structure of amylose, why and what characteristic does this give
coiled structure (almost like a cylinder) - due to the angles of the glycosidic bonds
this makes it compact, therefore really good for storage as you can fit more into a small space
what is amylopectin
a non-crystallizable form of starch, consisting of long, branched chains of α - glucose
what do the side branches of amylopectin allow it to do
its side branches allow the enzymes that break down the molecule to get to the glycosidic bonds easily - meaning that the glucose can be released quickly
is starch soluble or insoluble in water, why
insoluble in water and doesn’t affect water potential, therefore doesn’t cause water to enter cells by osmosis which would make them swell - making it good for storage
what test do you use for starch
iodine test
how is the iodine test carried out
add iodine dissolved in potassium iodide solution to the test sample - if there’s starch present the sample changes from brown orange to a dark blue black
what is the main energy storage material in animals
glycogen
where do animals also get energy, how is it stored
glucose - animals store excess glucose as glycogen
what is glycogen a polysaccharide of
α - glucose
what is glycogen’s structure similar to
amylopectin - except that it has loads more side branches, so stored glucose can be released quickly
why is glycogen good for storage
it is a compact molecule
what is cellulose a major component of
cell walls in plants
what is cellulose made of
long, unbranched chains of beta-glucose
how are cellulose chains formed
when beta-glucose molecules bond
what are microfibres
cellulose chains linked together by hydrogen bonds forming strong fibres (microfibres)
why are microfibres important to cellulose
strong fibres mean cellulose provides structural support for cells
what is a monosaccharide
the monomers from which larger carbohydrates are made
what are four examples of reducing sugars that are monosaccharides
glucose, galactose, fructose, lactose
what is one example of a reducing sugar that is a disaccharide
maltose
