Biology

• Eukaryotic


  Has membrane bound organelles e.g. Animal cell has mitochondria, ribosomes and a nucleus
• Prokaryotic


  No membrane bound organelles, e.g. bacteria and viruses
• Cell components common to animal and plant cells


  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Mitochondria
  • Ribosomes
• Additional components found in plant cells


  • Vacuole
  • Chloroplasts
  • Cell wall
• The 5 kingdoms


  • Plants
  • Animals
  • Fungi
  • Protoctists
  • Bacteria
• Multicellular


  Contains many cells
• Where carbohydrates are stored

  • Animals: Glycogen
  • Plants: Starch
  • Fungi: Glycogen
• Saprotrophic nutrition


  The use of digestive enzymes to extracellularly break down dead matter
• Pathogen


  A micro-organism which causes disease
• Types of pathogens


  • Virus
  • Bacteria
  • Protoctist
  • Fungi
• Viruses are non-living, they can only reproduce inside another living cell
• Fungi use saprotrophic nutrition
• Cells are a group of organelles working together to perform the same function
• Tissue


  A group of cells working together to perform the same function
• Organ


  A group of tissues working together to perform the same function
• Organ system


  A group of organs working together to perform the same function
• Main plant organs


  • Leaves
  • Roots
  • Stems
  • Flowers
• Main human organ systems


  • Reproductive system
  • Circulatory system
  • Digestive system
  • Gas exchange system
  • Nervous system
  • Excretory system
  • Endocrine system
• Organs in the digestive system


  • Oesophagus
  • Stomach
  • Small intestine
  • Large intestine
• Zygote


  Single cell formed after fertilisation occurs
• Formation of a 16 cell embryo

  2 cells -> 4 cells -> 8 cells -> 16 cells
• Differentiation


  Process whereby cells become specialised e.g. nerve cells
• Stem cell


  A cell which has the potential to divide many times whilst remaining undifferentiated (unspecialised)
• Types of stem cells


  • Embryonic
  • Adult
• Embryonic stem cells


  Found in early stage development of embryos, can differentiate into ANY type of cell
• Adult stem cells


  Found in particular tissues, unable to differentiate into any type of cell
• Stem cell therapy


  Use of stem cells to treat disease
• Stem cell therapy can be used to treat leukaemia by replacing cells lost in chemotherapy
• Advantages and disadvantages of embryonic stem cell therapy


  • Ability to differentiate into ANY type of cell
  • Could be used to treat Parkinson's disease, diabetes etc
  • Ethical issues as they come from unborn foetuses
• Elements found in biological molecules


  • Carbohydrates: Carbon, hydrogen, oxygen
  • Proteins: Carbon, hydrogen, oxygen, nitrogen (and sometimes sulfur)
  • Lipids: Carbon, hydrogen, oxygen
• Lipid structure


  3 fatty acids and 1 glycerol molecule
• Oils


  Plant lipids that are liquids at room temperature
• Protein structure


  Long chains of amino acids, there are 20 different amino acids
• Starch and glycogen


  Made up of simple sugars joined together
• Examples of proteins in the human body

  • Collagen and keratin found in skin and nails
  • All enzymes
  • Haemoglobin
• Food test for starch


  Add iodine, positive result is blue/black
• Food test for glucose


  Heat with water and Benedict's solution, positive result is brick red
• Food test for protein


  Add Biuret reagent, positive result is purple
• Food test for fat


  Add ethanol and water, positive result is milky white emulsion
• Role of genes


  Control the activities of the cell and determine which proteins are made