1A-Molecules of life, Sugars, Polysaccharides, Lipids Flashcards
Examples of polymers
carbohydrates, proteins and nucleic acids
What are polymers made of
monomers
Examples of monomers
monosaccharides, amino acids and nucleotides
What is a condensation reaction
How polymers are formed form monomers. Forms a chemical bond between monomers and releases a water molecule
What is a hydrolysis reaction
Breaks down a polymer back into a monomer by breaking the chemical bond using molecule of water
Examples of monosaccharides
glucose, fructose and galactose
What are beta glucose and alpha glucose
both are glucose molecules but are isomers so atoms connected in different ways
Draw structure of alpha glucose
refer back to pg21 in biology tectbook
draw structure of beta glucose
refer back to pg21 biology textbook
What are disaccharides
two monosaccharides joined together
How are monosaccharides joined together
by condensation reactions forming a glycosidic bond between two monosaccharides and a water molecule is released.
examples of disaccharides formed after a condensation reaction between two monosaccharides
a-glucose + a-glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose
Test for reducing sugars
heat sample with Benedict’s
reagent
if sample stays blue sample forms
green-yellow-
no reducing sugar present orange-brick red
precipitate
reducing sugar
present
Test for non reducing sugar
heat sample with Benedict’s
reagent
if sample stays blue sample forms
green-yellow-
no reducing sugar present orange-brick red
precipitate
reducing sugar
present heat sample with dilute hydrochloric acid then neutralise by adding sodium hydrogen carbonate. Heat sample with Benedict's reagent
stays blue sample forms
green-yellow-
orange-brick red
precipitate
no non reducing or
reducing sugar present non-reducing
sugar present
What is a polysaccharide
when more than two monosaccharides join together by condensation reactions
What is amylose made of
a-glucose molecules
Examples of polysaccharides
starch-amylose, amylopectin
glycogen
cellulose
How does the structure of amylose relate to its function
long, unbranches chains of a-glucose
coiled structure like a cylinder making it compact so good for storage so you can fit more in a small space
How does the structure of amylopectin relate to its function
long branched chains of a-glucose molecules
side branches allow enzymes to get at the glycosidic bonds easily
meaning glucose can be released quickly
Why is it good that starch is insoluble in water
it wont effect water potential so wont cause water to enter via osmosis
How does the structure of glycogen relate to its function
a lot of side branched coming off so stored glucose can be released quickly which is important for energy release in animals
also very compact making it good for storage
how does structure of cellulose relate to its function
long unbranched chains of beta glucose
cellulose chains linked together by hydrogen bonds to form strong fibres called microfibrils
this means provides structural support for cells
How to test for starch?
add iodine dissolved in potassium iodide solution to sample
if starch is present it will turn from browny orange to blue/black colour
what are lipids made from
hydrocarbons
two types of lipids
phospholipids and triglycerides
what are triglycerides made of
they have a molecule of glycerol and three fatty acids attached
what are the tail of triglycerides and what does it mean
they are hydrophobic meaning they repel water
why are lipids insoluble in water
because their tails are hydrophobic
What is the difference between saturated and unsaturated hydrocarbon tails
their R group refer to pg 27
saturated fatty acids don’t have double bonds between their carbon atoms
unsaturated fatty acids have double bonds between their carbon atoms causing the chain to kink
How is a triglyceride formed
formed by condensation reaction where a glycerol molecule joining with a fatty acids.
an ester bond is formed between them releasing a molecule of water. happens twice to form triglyceride refer to pg 28
what do phospholipids consist of
they have a glycerol molecule and two fatty acids and a phosphate group
why are phospholipids important in the cell membrane
because phosphate group is hydrophilic (attracts water) but fatty acids are hydrophobic
properties of triglycerides
used for energy storage because their long hydrocarbon tails which contain lots of chemical energy so a lot of energy is released when they’re broken down.
also insoluble in water so don’t effect the water potential of the cell
triglyceride bundle together as insoluble droplets because the tails are hydrophobic so are facing inwards shielding themselves with the glycerol molecule.
what properties of phospholipids is important for making up the bilayer of the cell memebrane
their heads are hydrophilic and their tails are hydrophobic so they create a double layer where the heads are facing outwards and their tails are facing inwards.
the centre is hydrophobic so water soluble molecules cant get past easily. this is why its found in the bilayer of cell membranes so not everything passes through
how to test for lipid
shake substance with ethanol for about a minute then pour solution into water
any lipid will show up as milky emulsion
