Biology

• Features that all living organisms share

  • Movement
  • Respiration
  • Sensitivity
  • Nutrition
  • Excretion
  • Reproduction
  • Growth
• Organelles that both animal and plant cells share


  • Cell membrane
  • Cytoplasm
  • Nuclei
  • Nucleus
  • Ribosomes
  • Mitochondria
• Additional organelles in plant cells

  • Cell wall
  • Vacuole
  • Chloroplasts
• Nucleus


  Controls the activities of the cell
• Cytoplasm


  Where chemical reactions take place
• Cell membrane


  Controls what enters and leaves the cell
• Ribosomes


  Where protein synthesis takes place, i.e. where proteins are made
• Cell wall


  Made of cellulose, protects and supports the cell
• Vacuole


  Filled with cell sap, helps maintain the structure of the cell
• Chloroplasts


  Contain the green pigment chlorophyll, where photosynthesis takes place
• Eukaryotes


  Animal cells, contain membrane-bound organelles such as nuclei and mitochondria
• Prokaryotes


  Viruses and bacteria, contain no membrane-bound organelles, have strands of DNA or RNA instead of a nucleus
• Bacterial cell


  • Sometimes has a cell wall
  • Sometimes has a slime capsule
  • Sometimes has a flagella (tail) to help it move
  • Has a circular chromosome (nucleoid) instead of a distinct nucleus
  • Has plasmids (small rings of genetic material)
• Types of bacteria


  • Pathogenic (cause disease, e.g. pneumococcus, tuberculosis)
  • Non-pathogenic (useful, e.g. lactobacillus bulgaricus used in yoghurt making)
• Bacteria are unicellular (made of one cell only)
• Viruses


  • Much smaller than bacteria
  • Simply made of a protein coat containing DNA or RNA
  • Have no typical organelles
  • Are non-living, do not excrete, respond, grow, or reproduce
  • Are always pathogenic (e.g. flu virus, cold virus, HIV)
• Tobacco mosaic virus causes discoloration in plant leaves and stunts growth
• Protists


  • Some have animal-like properties (e.g. amoeba)
  • Some have plant-like properties (e.g. algae, euglena)
  • Plasmodium causes malaria
• Protists can be unicellular or multicellular
• Fungi


  • Have a cell wall made of chitin
  • Have a cell membrane, cytoplasm, vacuole
  • Do not have chloroplasts
  • Have thread-like structures called hyphae that form a network called mycelium
  • Carry out saprotrophic nutrition (secrete enzymes onto dead matter to break it down and absorb nutrients)
• Examples of fungi


  • Yeast
  • Mushrooms
• The five kingdoms are: plants, animals, protists, bacteria, and fungi
• Carbohydrate storage


  In animals: glycogen

  In plants: starch

  In fungi: glycogen
• Cell


  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
• Organism


  A group of organ systems working together to perform the same function
• Organ systems in the body

  • Digestive system
  • Endocrine system
  • Reproductive system
  • Circulatory system
  • Respiratory system
  • Nervous system
  • Excretory system
• The digestive system includes organs like the stomach, esophagus, pancreas, small intestine, and large intestine
• Zygote


  The cell formed when a sperm and egg meet at fertilization
• Enzyme


  A biological catalyst that speeds up the rate of a chemical reaction without being used up
• Active site


  The biologically active part of an enzyme molecule where the substrate binds
• Enzyme catalysis

  1. Substrate binds to active site

  2. Forms enzyme-substrate complex

  3. Complex splits to form product
• Digestive enzymes

  • Amylase (breaks down starch into glucose)
  • Proteases (break down proteins into amino acids)
  • Lipase (breaks down lipids/fats into fatty acids and glycerol)
• As temperature increases


  Enzyme activity increases up to the optimum temperature
• As temperature continues to increase above the optimum


  Enzyme activity decreases due to denaturation
• As pH moves away from the optimum pH


  Enzyme activity decreases due to denaturation
• Diffusion


  The net movement of particles from an area of high concentration to an area of low concentration
• Osmosis


  The net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane