Molecular Biology
2.1 Molecules to Metabolism:
Metabolism:
Is the set of all the life-sustaining reactions within the cells of living organisms
These reactions are catalysed by enzymes and allow organisms to grow and reproduce, maintain their
structures, and respond to their environments
Many of these reactions occur in the cytoplasm, but some are extracellular including digestion and the
transport of substances into and between cells
The word metabolism can refer to the sum of all chemical reactions that occur in living organisms
Cell Biochemistry:
Molecules that make up living things are
○ Carbohydrates: e.g. glucose, starch, cellulose
○ Lipids: e.g. fats, waxes, oils
○ Proteins: e.g. enzymes, hormones, collagen, muscle
○ Nucleic acids: e.g. DNA
○ Minerals: e.g. calcium, iron, sodium
○ Water
Organic Compounds:
Organic compounds contain carbon and are
found in living things
○ E.g. glucose, ribose, amino
acids, glycerol, fatty acids
○ Usually contain C-H or C-C
bonds
○ Each carbon atom forms
four covalent bonds, each
hydrogen atom forms one
covalent bond, each oxygen
, and sulfur atom forms two covalent bonds and each nitrogen atom forms three covalent
bonds
○ Carbon compounds include carbohydrates, lipids, proteins and nucleic acids
Organic Subunits:
Complex macromolecules may commonly be comprised of smaller, recurring subunits called monomers
○ Carbohydrates, nucleic acids and proteins are all comprised of monomeric subunits that
join together to form larger polymers
○ Lipids do not contain recurring monomers, however certain types may be composed of
distinct subunits (e.g. triglycerides)
Carbohydrates:
Carbohydrates are composed of monomers called
monosaccharides ('single sugar unit')
○ Monosaccharides are the
building blocks of disaccharides
(two sugar units) and
polysaccharides (many sugar
units)
○ Most monosaccharides form ring
structures and can exist in
different 3D configurations (stereoisomers)
Lipids:
Lipids exist as many different classes that vary in
structure and hence do not contain a common
recurring monomer
However several types of lipids (triglycerides,
phospholipids, waxes) contain fatty acid chains as
part of their overall structure
○ Fatty acids are long chains of hydrocarbons that may or may not contain double bonds
(unsaturated vs saturated)
Proteins:
Proteins are composed of monomers called amino acids, which join together to form
polypeptide chains
, ○ Each amino acid consists of a central carbon connected to an amine group (NH 2) and an
opposing carboxyl group (COOH)
○ A variable group (denoted ‘R’) gives different amino acids different properties e.g. polar
Nucleic Acids:
Nucleic acids are composed of monomers called
nucleotides, which join together to form polynucleotide
chains
Each nucleotide consists of 3 components – a pentose
sugar, a phosphate group and a nitrogenous base
○ The type of sugar and composition of bases differs between DNA and RNA
Carbohydrates:
The structure of complex carbohydrates may vary depending on the composition of monomeric subunits
Polysaccharides may differ according to the type of monosaccharide they possess and the way the
subunits bond together
Glucose monomers can be combined to form a variety of different polymers – including glycogen,
cellulose and starch
Lipids:
Lipids can be roughly organised into one of three main classes:
, ○ Simple (neutral) lipids – Esters of fatty acids and alcohol (e.g. triglycerides and waxes)
○ Compound lipids – Esters of fatty acids, alcohol and additional groups (e.g.
phospholipids and glycolipids)
○ Derived lipids – Substances derived from simple or compound lipids (e.g. steroids and
carotenoids)
Proteins:
Amino acids join together by peptide bonds which form between the amine and carboxyl groups of
adjacent amino acids
The fusion of two amino acids creates a dipeptide, with further additions resulting in the formation of a
polypeptide chain
The subsequent folding of the chain depends on the order of amino acids in a sequence (based on
chemical properties)
2.1 Molecules to Metabolism:
Metabolism:
Is the set of all the life-sustaining reactions within the cells of living organisms
These reactions are catalysed by enzymes and allow organisms to grow and reproduce, maintain their
structures, and respond to their environments
Many of these reactions occur in the cytoplasm, but some are extracellular including digestion and the
transport of substances into and between cells
The word metabolism can refer to the sum of all chemical reactions that occur in living organisms
Cell Biochemistry:
Molecules that make up living things are
○ Carbohydrates: e.g. glucose, starch, cellulose
○ Lipids: e.g. fats, waxes, oils
○ Proteins: e.g. enzymes, hormones, collagen, muscle
○ Nucleic acids: e.g. DNA
○ Minerals: e.g. calcium, iron, sodium
○ Water
Organic Compounds:
Organic compounds contain carbon and are
found in living things
○ E.g. glucose, ribose, amino
acids, glycerol, fatty acids
○ Usually contain C-H or C-C
bonds
○ Each carbon atom forms
four covalent bonds, each
hydrogen atom forms one
covalent bond, each oxygen
, and sulfur atom forms two covalent bonds and each nitrogen atom forms three covalent
bonds
○ Carbon compounds include carbohydrates, lipids, proteins and nucleic acids
Organic Subunits:
Complex macromolecules may commonly be comprised of smaller, recurring subunits called monomers
○ Carbohydrates, nucleic acids and proteins are all comprised of monomeric subunits that
join together to form larger polymers
○ Lipids do not contain recurring monomers, however certain types may be composed of
distinct subunits (e.g. triglycerides)
Carbohydrates:
Carbohydrates are composed of monomers called
monosaccharides ('single sugar unit')
○ Monosaccharides are the
building blocks of disaccharides
(two sugar units) and
polysaccharides (many sugar
units)
○ Most monosaccharides form ring
structures and can exist in
different 3D configurations (stereoisomers)
Lipids:
Lipids exist as many different classes that vary in
structure and hence do not contain a common
recurring monomer
However several types of lipids (triglycerides,
phospholipids, waxes) contain fatty acid chains as
part of their overall structure
○ Fatty acids are long chains of hydrocarbons that may or may not contain double bonds
(unsaturated vs saturated)
Proteins:
Proteins are composed of monomers called amino acids, which join together to form
polypeptide chains
, ○ Each amino acid consists of a central carbon connected to an amine group (NH 2) and an
opposing carboxyl group (COOH)
○ A variable group (denoted ‘R’) gives different amino acids different properties e.g. polar
Nucleic Acids:
Nucleic acids are composed of monomers called
nucleotides, which join together to form polynucleotide
chains
Each nucleotide consists of 3 components – a pentose
sugar, a phosphate group and a nitrogenous base
○ The type of sugar and composition of bases differs between DNA and RNA
Carbohydrates:
The structure of complex carbohydrates may vary depending on the composition of monomeric subunits
Polysaccharides may differ according to the type of monosaccharide they possess and the way the
subunits bond together
Glucose monomers can be combined to form a variety of different polymers – including glycogen,
cellulose and starch
Lipids:
Lipids can be roughly organised into one of three main classes:
, ○ Simple (neutral) lipids – Esters of fatty acids and alcohol (e.g. triglycerides and waxes)
○ Compound lipids – Esters of fatty acids, alcohol and additional groups (e.g.
phospholipids and glycolipids)
○ Derived lipids – Substances derived from simple or compound lipids (e.g. steroids and
carotenoids)
Proteins:
Amino acids join together by peptide bonds which form between the amine and carboxyl groups of
adjacent amino acids
The fusion of two amino acids creates a dipeptide, with further additions resulting in the formation of a
polypeptide chain
The subsequent folding of the chain depends on the order of amino acids in a sequence (based on
chemical properties)
