Biological molecules Flashcards
Define nutrients
Nutrients are chemical substances in food that provide energy and materials needed by the body
Define a polymer
A polymer is a macro-molecule, composed of many repeated subunits
Define condensation reaction
Condensation reaction is a chemical reaction where 2 or more simple molecules join to form a larger biological molecule with the removal of water
Define hydrolysis
Hydrolysis is the splitting up of a complex biological molecule into its component units with the addition of water
Give an example of how hydrolysis works in our body
Process of digestion
Name some polysaccharides and their monomers
Starch - Glucose
Glycogen - Glucose
Cellulose - Glucose
What elements are carbohydrates made up of
- Carbon
- Hydrogen
- Oxygen
What are the groups of carbohydrates
- Monosaccharides (glucose, fructose, galactose)
- Disaccharides (maltose, sucrose, lactose)
- Polysaccharides (starch, glycogen, cellulose)
What are the properties of monosaccharides
- Sweet tasting
- Soluble in water
What is the bond formed between monosaccharides
Glycosidic bond
What is maltose made up of
Glucose + Glucose
What is sucrose made up of
Glucose + Fructose
What is lactose made up of
Glucose + Galactose
Where is starch found
Plants only
Where is glycogen found
Animals
How are starch, glycogen and cellulose formed
Condensation reaction of large numbers of glucose molecules
Where is glycogen stored in mammals
- Liver
- Muscles
Why are starch and glycogen suitable as storage materials
- Easily hydrolysed to glucose when needed
- Insoluble in water so it will not affect water potential of cells
- Too large to diffuse through cell membranes
- Compact shape occupies less space than the individual glucose molecules that make up a starch or glycogen molecule
How are glucose molecules joined up in starch
- Long straight chains
- Branched chains
How are glucose molecules joined up in glycogen
Highly branched chains
Why does cellulose have different properties compared to starch and glycogen
Glucose molecules that form cellulose are bonded differently
What are the functions of a cellulose cell wall
- Provide mechanical support for plant
- Resist expansion when water enters plant by osmosis
What are the functions of carbohydrates
- Glucose is a ready source of energy for body to utilise
- Glucose acts as a substrate for respiration
- (Deoxy)ribose sugar used in formation of nucleic acids
- Forms lubricants like mucus
- Forms nectar in flowers
- Cellulose forms supporting structures
What elements are lipids made up of
- Carbon
- Hydrogen
- Oxygen
What are the properties of lipids
- Insoluble in water
- Soluble in organic solvents
What are the groups of lipids
- Triglycerides (fatty acids, glycerol)
- Phospholipids
Define a fatty acid
A fatty acid is a long hydrocarbon chain that has a carboxyl functional group
When is a hydrocarbon chain saturated
When it has no carbon-carbon double bonds
What is the formula of glycerol
C3H8O3
How is one triglyceride molecule formed
Formation of one triglyceride molecule is by the condensation reaction of 3 fatty acid molecules and 1 glycerol molecule with the removal of 3 water molecules
What is an ester bond
Bond formed between 1 fatty acid and glycerol
What are the functions of triglycerides
- Used for energy storage as it can yield twice as much energy as carbohydrates
- Acts as a heat insulator in blubber
- Allows for buoyancy in aquatic mammals
- Acts as a protective layer to absorb shock
- Important component of myelin sheath as it acts as electrical insulator
- Provides metabolic water when oxidised
- Acts as a solvent
Why do triglycerides yield more energy than carbohydrates
Triglycerides contain more carbon-hydrogen bonds than carbohydrates
What are phospholipids
A group of compound lipids that contains 2 fatty acid molecules, 1 glycerol molecule, and a phosphate group
Is the phosphate group of a phospholipid hydrophilic or hydrophobic
Hydrophilic
Are the fatty acid tails of a phospholipid hydrophilic or hydrophobic
Hydrophobic
What are the functions of phospholipids
- Major component of biological membranes
What elements are proteins made up of
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
(Sometimes sulfur)
Why do proteins have diverse functions
Each protein type has a unique 3D shape
What is the monomer of a protein or polypeptide
Amino acid
What is the monomer of a polynucleotide
Nucleotide
What is a peptide bond
Bond between amino group of an amino acid and carboxyl group of another amino acid
How are polypeptides formed
Polypeptides are formed from the condensation reaction of amino acids with the removal of water molecules
What are the functions of proteins
- Synthesis of new cells
- Biological catalysts like enzymes speed up reactions
- Chemical messengers like hormones stimulate target organs
- Transport proteins like haemoglobin transport oxygen
- Structural proteins like collagen forms skin and bones
- Antibodies are used to protect against infections
- Source of energy during starvation
What is Kwashiorkor
A form of protein deficiency disease
