Biological Molecules 27 Sep 2021
Biological Molecules
Introduction to biological molecules
Covalent bonding: within molecules, sharing of electrons between two non-metals intra molecular
Ionic bonding: within molecules/compounds, transfer of electrons from a metal to a non metal. metals will
form positive ions, non metals will form negative ions and between oppositely charged ions there will be an
electrostatic attraction, intra molecular
Hydrogen Bonding: between molecules, weak attraction between opposite dipoles, inter molecular
intra molecular: very strong
inter molecular: weak
Polysaccharides: chain of monosaccharides -
carbohydrate
Polypeptide: chain of peptides - amino acids
protein
Polynucleotide: chain of nucleotides - DNA
Condensation reactions - reactions that produce
water each time a new sub-unit is attached
Hydrolysis - polymers can be broken down to
monomers by the addition of water
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, Biological Molecules 27 Sep 2021
Carbohydrates
Made of carbon, hydrogen, oxygen Monosaccarides - glucose, galactose and
fructose. Formula: (CH2O)n
Glucose + Glucose = Maltose
Glucose + Galactose = Lactose
Glucose + fructose = sucrose
Polysaccarides:
- Formed by combining
together many
monosaccharides
- Large molecules so
they are insoluble -
suitable for storage, ie
cellulose adaptation
Test for Presence of Starch:
Add iodine to test sample if the sample changes
from orange to a blue-black starch is present
2 of 10
Biological Molecules
Introduction to biological molecules
Covalent bonding: within molecules, sharing of electrons between two non-metals intra molecular
Ionic bonding: within molecules/compounds, transfer of electrons from a metal to a non metal. metals will
form positive ions, non metals will form negative ions and between oppositely charged ions there will be an
electrostatic attraction, intra molecular
Hydrogen Bonding: between molecules, weak attraction between opposite dipoles, inter molecular
intra molecular: very strong
inter molecular: weak
Polysaccharides: chain of monosaccharides -
carbohydrate
Polypeptide: chain of peptides - amino acids
protein
Polynucleotide: chain of nucleotides - DNA
Condensation reactions - reactions that produce
water each time a new sub-unit is attached
Hydrolysis - polymers can be broken down to
monomers by the addition of water
1 of 10
, Biological Molecules 27 Sep 2021
Carbohydrates
Made of carbon, hydrogen, oxygen Monosaccarides - glucose, galactose and
fructose. Formula: (CH2O)n
Glucose + Glucose = Maltose
Glucose + Galactose = Lactose
Glucose + fructose = sucrose
Polysaccarides:
- Formed by combining
together many
monosaccharides
- Large molecules so
they are insoluble -
suitable for storage, ie
cellulose adaptation
Test for Presence of Starch:
Add iodine to test sample if the sample changes
from orange to a blue-black starch is present
2 of 10
