Applicable for A-Level, IB, DSE, AP-Level Exams

Biological Molecules    Cell Structure    Cell Transport    Immunology    Exchange    Mass Transport    DNA, Genes & Protein Synthesis    Genetic Diversity    Biodiversity    Photosynthesis    Respiration    Energy & Ecosystems    Stimuli and Response    Nervous Coordination & Muscles    Homeostasis    Inheritance    Populations & Evolution    Ecosystems    Gene Expression    Recombinant DNA Technology   


In eukaryotic cells, DNA associates with histone proteins to form chromosomes. However, in eukaryotic cells, DNA is not associated with histone proteins and are considered naked. A gene is a base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA.

Download PDF (1 page)

RNA and Protein Synthesis

Protein synthesis is the process of making proteins from the genetic code. There are two main steps: Transcription and Translation. Transcription is the process of transcribing DNA base sequences into mRNA. This is done by breaking the hydrogen bonds within the double helix and free RNA nucleotides binding to each template strand by complementary base pairing. RNA polymerase then joins up the phosphodiester bonds.

Translation is the process of assembling the polypeptide from mRNA and it occurs within the ribosomes. As mRNA associates with the ribosome and ribosome wraps around 2 codons at once, codon on mRNA is complementary to anti-codon on tRNA. tRNA then brings then appropriate amino acid and a peptide bond is formed from a condensation reaction to form a polypeptide.

Download PDF (2 pages)