20 FACTS OCT 2024

• Pyrimidine bases 


  include cytosine, uracil and thymine
• Phosphodiester bonds

  are formed between the deoxyribose and the phosphate group in DNA
• Peptide bonds 


  form between the amino group of one amino acid and the acid group of another amino acid
• Unsaturated triglycerides 


  contain C=C
• Phospholipids 


  are formed when one of the three fatty acid tails in a triglyceride is replaced with a phosphate group
• Non-competitive inhibition 


  is caused by an inhibitor attaching to an enzyme and altering the shape of the active site so no enzyme-substrate complexes can form
• The Biuret Test 


  tests for protein. The solution turns from blue to lilac.
• Amylopectin 


  is a polysaccharide of glucose molecules and contains both 1,4 and 1,6 glycosidic bonds
• The enzyme lactase 


  catalyses the hydrolysis of lactose into the monosaccharides glucose and galactose
• A triglyceride 


  is formed when a glycerol molecule reacts with three fatty acids through a condensation reaction, forming an ester bond.
• Homogenation 


  The first stage of cell fractionation when cells are broken up by a homogeniser (blender) and organelles are released from the cell
• Ultracentrifugation 


  the second stage of cell fractionation when the fragments in filtered homogenate are separated in a machine called a centrifuge
• Golgi


  Organelle that contains a stack of membranes that make up flattened sacs (cisternae) where glycoproteins are synthesised, lipids are transported, modified and stored, proteins are packaged and lysosomes are formed.
• Capsid

  A protein coat which encloses the nucleic acid in a virus
• Centromere 


  The place where the two copies of DNA after replication are joined
• Interphase 


  The period of the cell cycle where the cell is not dividing
• Prophase


  The first stage of mitosis when the chromosomes become visible and when spindle fibres develop. The nucleolus disappears and the nuclear envelope breaks down.
• Metaphase

  The second stage of mitosis when the chromosomes arrange themselves across the equator of the cell.
• Anaphase 


  The third stage of mitosis when the centromeres divide into two and the spindle fibres pull the individual chromatids making up the chromosome apart to their respective, opposite poles of the cell.
• Telophase

  The fourth stage of mitosis when chromosomes reach their respective poles and become longer and thinner, finally disappearing altogether, leaving only wide spread chromatin. The soundless fibres disintegrate and the nuclear envelope and nucleolus reform.