Molecules of metabolism Topic 2.1 Biology SL
Molecular biology
➢ Molecular biology is the chemistry of living organisms
➢ Organic chemistry is the study of compounds that contain carbon
○ Not all compounds that consist of carbon are classified as organic
➢ Molecular biology is a lot about carbon
○ It is the keystone element for life on Earth and that’s why we say that life on
Earth is carbon based
○ It is able to form 4 covalent bonds
■ Share 4 electrons with other atoms to form a stable octet
➢ Other very common elements are:
○ Hydrogen
○ Oxygen
○ Nitrogen
○ Phosphorus
➢ Together these elements form macromolecules
○ The 4 most common ones from which all life consists are:
■ Proteins / polypeptides => amino acids
■ Carbohydrates => monosaccharides
■ Nucleic acids => nucleotides
■ Lipids => glycerol, fatty acids, phosphate groups
➢ Depending on what subcomponents/monomers that are involved and the size of
the molecule, the molecule might belong to one or another subcategory and it will
be given different properties
Category Subcategory Example molecules
Carbohydrates Monosaccharides Glucose, galactose,
fructose, ribose
Disaccharides Maltose, lactose, sucrose
Polysaccharides Starch, glycogen, cellulose,
chitin
Proteins Enzymes, antibodies,
peptide hormones
Lipids Triglycerides Fat stored in adipose cells
1
,Molecules of metabolism Topic 2.1 Biology SL
Phospholipids Lipids forming a bilayer in
cell membranes
Steroids Some hormones
Nucleic acids Deoxyribonucleic acid,
ribonucleic acid, adenosine
triphosphate
Macromolecules
➢ Proteins
○ Many functions in organisms
○ Forming hair, muscles, hormones, etc
○ Made of amino acids
➢ Carbohydrates
○ Primary energy source of plants and animals
➢ Lipids
○ Used to store energy
○ Makes up most of the plasma membrane
➢ Nucleic acids
○ Used to store genetic information
○ Helps cell assemble proteins
Metabolism
➢ Macromolecules are formed or broken down in the metabolism
➢ Metabolism i s all the enzyme-catalyzed reactions in an organism and within all
cells
➢ A catalyst is a compound that increases the rate of a chemical reaction without
being consumed itself
➢ An enzyme is a protein molecule acting as a catalyst
○ Very specific to what it catalyzes
➢ Metabolism can be described as collisions of molecules that move in their aqueous
environment
➢ There are factors that determine if a reaction will happen or not after the collision.
Some of them are:
○ Identity of the colliding molecules
○ Orientation of the colliding molecules
2
, Molecules of metabolism Topic 2.1 Biology SL
■ Where they hit each other
○ The speed of the molecules when they collide
➢ Enzymes have a specific shape into which reactants can fit, at a molecular location
called the a
ctive side
○ By having an active side, the enzyme increases the likelihood of a reaction
Catabolism & Anabolism
➢ Metabolism is the sum of catabolism and anabolism
➢ Catabolism i s the breakdown of macromolecules into their subcomponents /
monomers
○ Enzyme-catalyzed
○ Example: food digestion
➢ Anabolism i s the formation of macromolecules from their subcomponents /
monomers
○ Enzyme-catalyzed
○ Example: building of muscles
➢ A hydrolysis r eaction occurs when water is a reactant
○ Catabolism
➢ A condensation r eaction is when water is a product
○ Anabolism
○ Needs another type of enzymes capable of creating rather than breaking
bonds
3
Molecular biology
➢ Molecular biology is the chemistry of living organisms
➢ Organic chemistry is the study of compounds that contain carbon
○ Not all compounds that consist of carbon are classified as organic
➢ Molecular biology is a lot about carbon
○ It is the keystone element for life on Earth and that’s why we say that life on
Earth is carbon based
○ It is able to form 4 covalent bonds
■ Share 4 electrons with other atoms to form a stable octet
➢ Other very common elements are:
○ Hydrogen
○ Oxygen
○ Nitrogen
○ Phosphorus
➢ Together these elements form macromolecules
○ The 4 most common ones from which all life consists are:
■ Proteins / polypeptides => amino acids
■ Carbohydrates => monosaccharides
■ Nucleic acids => nucleotides
■ Lipids => glycerol, fatty acids, phosphate groups
➢ Depending on what subcomponents/monomers that are involved and the size of
the molecule, the molecule might belong to one or another subcategory and it will
be given different properties
Category Subcategory Example molecules
Carbohydrates Monosaccharides Glucose, galactose,
fructose, ribose
Disaccharides Maltose, lactose, sucrose
Polysaccharides Starch, glycogen, cellulose,
chitin
Proteins Enzymes, antibodies,
peptide hormones
Lipids Triglycerides Fat stored in adipose cells
1
,Molecules of metabolism Topic 2.1 Biology SL
Phospholipids Lipids forming a bilayer in
cell membranes
Steroids Some hormones
Nucleic acids Deoxyribonucleic acid,
ribonucleic acid, adenosine
triphosphate
Macromolecules
➢ Proteins
○ Many functions in organisms
○ Forming hair, muscles, hormones, etc
○ Made of amino acids
➢ Carbohydrates
○ Primary energy source of plants and animals
➢ Lipids
○ Used to store energy
○ Makes up most of the plasma membrane
➢ Nucleic acids
○ Used to store genetic information
○ Helps cell assemble proteins
Metabolism
➢ Macromolecules are formed or broken down in the metabolism
➢ Metabolism i s all the enzyme-catalyzed reactions in an organism and within all
cells
➢ A catalyst is a compound that increases the rate of a chemical reaction without
being consumed itself
➢ An enzyme is a protein molecule acting as a catalyst
○ Very specific to what it catalyzes
➢ Metabolism can be described as collisions of molecules that move in their aqueous
environment
➢ There are factors that determine if a reaction will happen or not after the collision.
Some of them are:
○ Identity of the colliding molecules
○ Orientation of the colliding molecules
2
, Molecules of metabolism Topic 2.1 Biology SL
■ Where they hit each other
○ The speed of the molecules when they collide
➢ Enzymes have a specific shape into which reactants can fit, at a molecular location
called the a
ctive side
○ By having an active side, the enzyme increases the likelihood of a reaction
Catabolism & Anabolism
➢ Metabolism is the sum of catabolism and anabolism
➢ Catabolism i s the breakdown of macromolecules into their subcomponents /
monomers
○ Enzyme-catalyzed
○ Example: food digestion
➢ Anabolism i s the formation of macromolecules from their subcomponents /
monomers
○ Enzyme-catalyzed
○ Example: building of muscles
➢ A hydrolysis r eaction occurs when water is a reactant
○ Catabolism
➢ A condensation r eaction is when water is a product
○ Anabolism
○ Needs another type of enzymes capable of creating rather than breaking
bonds
3
