Biology unit 2
Biochemistry and bonds
Monomers and polymers.
The term monomer refers to a single, small molecule, many of which can be joined together to form a polymer.
Poly peptides and proteins
DNA and RNA
Condensation and hydrolysis
The chemical reaction that links biological monomers together is called a condensation reaction; this reaction happens repeated times to form a polymer. In condensation reactions
· A water molecule is released
· A new covalent bond is formed
· A larger molecule is formed by the monomers bonding together
The opposite of condensation is called a hydrolysis reaction when a polymer separates back into monomers using water. In hydrolysis reactions
o A water molecule is used
o A covalent bond is broken
o Smaller molecules are formed by splitting larger molecules
Carbohydrates are used as:
o an energy source - which are released from glucose during respiration
o energy store – e.g. starch
o structure – e.g. cellulose
α glucose and βglucose
Levels of protein structure
Primary - sequence of amino acids. Involves peptide bonds
Secondary - the coiling of polypeptide chains to form an alpha helix or the folding of polypeptide chains to form beta plated sheets. This involves hydrogen bonds (hold the coils/folds together)
Tertiary - the coils and folds then coil and fold themselves.
This is the final 3D structure for proteins made of one polypeptide chain
Disulphide bonds (between sulphur on one cysteine molecule and sulphur on another) sulphur is a type of amino acid.
Ionic bonds (between +ve R group and -ve R group)
Hydrogen bonds between +ve molecule and -ve hydrogen
Hydrophobic and hydrophilic interactions.
Quaternary structure - How different polypeptide chains are assembled/held together.
Involves all the bonds above.
Final 3D structure for proteins made of more than one pp chain
Deoxyribonucleic Acid: The molecule that stores genetic information. It is present in the chromosomes, inside the nuclei of cells.
Organic bases: Adenine, Guanine, Cytosine, and Thymine pairing = C&G
Purine bases: Organic bases that are made up of six-sided rings joined to a five-sided ring. These are Adenine and Guanine.
Pyrimidine bases: Organic bases that are made up of a single six-sided ring. These are Thymine and Cytosine.
Nucleotides: These are made up of a phosphate group a deoxyribose or ribose (A five carbon sugar) and an organic base. Nucleotides join together by a series of condensation reactions to form a polynucleotide, such as DNA or RNA.
DNA Structure: A DNA molecule is made up of two nucleotide strands, with one upside-down compared to the other. Each polynucleotide strand is extremely long and is wound around the other to form a double helix. - The two strands are…