bio ocr f212

  • Created by: Zoe
  • Created on: 19-05-12 14:26

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.








Amino acids

Poly peptides and proteins

Nucleic acids



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 Cn(H20)n

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
this involves:
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




Nice and condesned well done