Biological Molecules Flashcards
What are monomers
Molecules that ca be linked together to form long chains.
What are polymers
Long chains of monomer sub-units.
What are the properties of carbon
- Forms long chains
- 4 covalent bonds
- Can bond with other chain/rings of carbon and gain other properties
What are the monomers of carbohydrates
Monosacchrides such as
glucose
fructose
galactose
What are polymers of carbohydrates
Polysacchrides such as
starch
cellulose
How many forms of carbohydrates are there
3
Monosacchrides
Disacchrides ( sucrose, maltose and lactose)
Polysacchrides
What are isomers
Compounds with the same molecular formula but different molecular arrangement
What are the isomers of glucose
Alpha glucose
Beta glucose
What are the structures of alpha and beta glucose
.
Product of condensation of alpha glucose molecules
Starch and Glycogen
Properties of starch
- Made of 80% amylopectin and 20% amylose
- Insoluble (doesnt affect water potential)
- Metabolically inactive
- Branches to give easy access to glucose
- Amylose makes it compact which makes it more suitable for storage
Glycosidic bonds for amylose and amylopectin
- 1,4
Properties of glycogen
- Condensation of Alpha glucose molecules
- Same structure as starch
- Insoluble (doesn’t affect water potential)
- Higher metabolic rate than starch which means that the respiratory rate can increase. it is therefore broken down more rapidly that starch
Cellulose
- Condensation of Beta glucose moleules
- Glucose molecules forms straight chains of 10,000 of glucose molecules
- The chains form hydrogen bonds which form cross links.
- Provides strength
- Grouped to form microfibrils to provide more strength
What are the monomers of lipids
monomer: fatty acid and glycerol
polymers: fats
Properties of lipids
- Insoluble in water
- Soluble in ethanol
- Stores energy
- Used for insulation
- Used for making biological membranes
- Acts as a hormone
What does a triglyceride look like
1 glycerol molecule and 3 fatty acids
What bond does it form?
Ester bond
Why are polyunsaturated chains more liqiud
The double bonds push the carbon atoms apart which alter their shape; making it more liquid
What are the properties of triglycerides
- Excellent energy storage
- Low mass to energy ratio ( much energy can be stored in a small volume)
- Non-polar (insoluble)
- Release water when oxidised (important source of water
What does a phospholipid look like
phosphate group, 2 fatty acids and 1 glycerol
hydrophilic head
hydrophobic tail
What are the properties of phospholipids
- Combine with carbohydrates to form glycolipids. This is important for cell recognition
- Hydrophilic head hold the surface membrane together
- They are polar
What is the test for lipids
Emulsion test
- Put food sample into a test tube
- Add ethanol to the sample
- Shake the test tube thoroughly
- Add water and shake gently
- Cloudy white colour indicates the presence of lipids
What are the monomers of proteins
Amino acids
What is the polymer of proteins
Polypeptide
What are the products of the condensation reaction of 2 polypeptides
Dipeptide+water
What bond holds the dipeptides together
peptide bonds
Explain the primary structure of a protein
It is a sequence of amino acids in a polypeptide chain formed by enzyme catalysed condensation reactions.
it decides the ultimate shape and hence its function . A single change can give it a complete different function.
Explain the secondary structure of a protein
Hydrogen bonds start to form between the amino acids. This automatically makes the chain coil into a alpha helix or a beta pleated sheet.
Explain the teriary structure of a protein
The chain is coiled or pleated even further and more bonds form between different parts of the polypeptide chain. This forms a 3D structure. The chain is held together by 4 bonds
*ionic bonds
hydrogen bonds
*hydrophilic and hydrophobic bonds
*disulphid bond ( 2 cysteine amino acids form a strong double bond between the sulfur atoms)
Explain the tertiary structure of a protein
The chain is coiled or pleated even further and more bonds form between different parts of the polypeptide chain. This forms a 3D structure. The chain is held together by 4 bonds
*ionic bonds
hydrogen bonds
*hydrophilic and hydrophobic bonds
*disulphid bond ( 2 cysteine amino acids form a strong double bond between the sulfur atoms)
Explain the Quaternary structure of a protein
It arises from a combination of number of different polypeptide chains and some non protein groups to form a large complex protein molecule. e.g haemoglobin
What is the test for proteins
Biuret test 1
- Add biurets regent to a food sample
- Observe colour change
- Purple means that protein is present
What is a Globular protein
Globular proteins are ball shaped proteins with a compact structure. Examples include enzymes, storage proteins and receptors. They contain hydrophobic parts which face towards the center and hydrophilic parts which face the edges.This makes them soluble.
Fibrous proteins
They have a very thin and long structure. They tend to have structural functions such as collagen, keratin and actin. They are always composed of many polypeptide chains . They are also insoluble in water.
