20 FACTS DEC 2024

• Gene

  Section of DNA on a chromosome that controls a feature by coding for formation of one or more specific polypeptides or a functional RNA (including rRNA and tRNA).
• Chromosome 


  A thread like structure made of protein and DNA by which hereditary information is physically passed from one generation to the next.
• Autosome


  A chromosome which is not a sex chromosome
• Degenerate


  A single amino acid may be coded for by more than one triplet code. 
• Non-overlapping


  Each base appears in only one triplet – each base is only read once. 
• Universal


  The genetic code is the same in all organisms – this is indirect evidence for evolution.
• Histones


  Proteins, which together with DNA, make up the chromosomes of eukaryotic cells.
• Chromatid


  Each of the two thread-like strands into which a chromosome divides that are joined together by a single centromere prior to cell division
• Locus


  The specific linear position of a particular gene on a certain chromosome
• Alleles

  Alternative forms of a particular gene with different base sequences, and therefore different codes
• Lymphocyte


  Type of white blood cell responsible for the immune response. They become activated in the presence of antigens. There are two types: B lymphocytes and T lymphocytes. 
• Lysosome


  Contain enzymes called lysozymes which they release into the phagosome which hydrolyse the bacterium.
• Phagosome


  A vesicle formed as the bacterium is engulfed by the phagocyte. The lysosome release their lysozymes into the phagosome.
• Helper T cells


  Contain receptors which respond to a single antigen. 
• Cytotoxic T cells


  Kill abnormal cells and body cells that are infected by pathogens by producing a protein called perforin which makes holes in the cell-surface membrane. 
• Humoral Immunity


  The type of response which involves B lymphocytes and antibodies.
• B Cells


  Each type of B cell produces a specific antibody that responds to one specific antigen. 
• Antibody


  A protein with specific binding sites produced by B cells in response to the presence of appropriate antigen.
• Natural Immunity


  A type of active immunity resulting from an individual becoming infected with a disease under normal circumstances.
• Artificial Immunity


  A type of active immunity resulting from vaccination. It involves inducing an immune response in an individual without them suffering symptoms of the disease.