The Nature and Variety of Organisms

• In order for a living organsim to be one it needs to MRS C GREN. Move, Respond to surrondings, Control their internal conditions, Grow, Excrete their waste , Reproduce, need Nutrition
• Organelles are tiny structures inside cells.
• Cells can be eukaryotic or prokaryotic. Eukaryotic cells are complex and include all animal and plant cells.
• In a typical animal cell: nucleus - contain genetic material that controls the cell activities.
• Cell membrane - controls the substances that go in and out.
• Cytoplasm - where most of the chemical reactions take place. Contains enzymes.
• Mitochondria - small organelles where most of reactions for anaerobic respiration take place.
• Ribosomes = site of protein synthesis in the cell.
• Plant cells have a few extras, such as chloroplasts, cell walls and vacuole. Chloroplasts - contain chlorophyll and are where photosynthesis takes place.
• Cell wall - it supports the cell and strengthens it, it's made of cellulose.
• Vacuole - contains cell sap and helps to support the cell.
• A tissue is a group of similar cells that work together to carry out a particular function.
• An organ is a group of different tissues that work together to perform a function.
• Organs work together to form organ systems and each system does a different job.
• Similar tissues > Tissues > Organs > Organ systems
• Cells are specialised to carry out a specific function and their structures can vary.
• Cell differentiation is the process by which a cell changes to become specialised for its job.
• Undifferentiated cells (stem cells) can divide to produce lots more undifferentiated cells that can differentiate into different cells depending on what instructions they are given.
• Stem cells are found in early human embryos and adults also have stem cells in their bone marrow but they can't turn into any type of cell, only certain ones. They both can be grown in a lab to produce clones and made to differentiate into specialised cells.
• Stem cells may be able to cure many diseases by replacing faulty cells with healthy ones but stem cells grown in the lab may become contaminated with a virus that could be passed on to the patient and make them sicker.
• Plant, animal and fungi are eukaryotic organisms.
• Plants - multicellular, have chloroplast which means they can photosynthesis, have cell walls made up of cellulose, store carbohydrates as sucrose or starch. EXAMPLES = cereals (maize) , peas and beans.
• Animals - multicellular, don't have chloroplasts, don't have cell walls, most have nervous coordination, usually can move around, often store carbohydrate in the form of glycogen.
• Fungi - some are single celled, multicellular ones have a body called a mycelium which is made up of hyphae. can't photosynthesise, cell walls made of chitin, most feed by saprotrophic nutrition, store carbohydrate as glycogen EXAMPLES = yeast (single celled) , mucor (multicellular)
• Saprotrophic nutritionon is when they secrete extracellular enzymes into the area outside their body to dissolve their food, so they can then absorb the nutrients.
• Protoctists are eukaryotic organisms.
• Bacteria are prokaryotic organisms.
• • Protoctists are single celled and microscopic.
  • Some have chloroplasts and are similar to plant cells.
  • Others are more like animal cells.
  • example are chlorella (plant cell like) , amoeba (animal cell like)
• • Bacteria are single celled and microscopic.
  • They don't have a nucleus.
  • They have a circular chromosome of DNA.
  • Some can photosynthesise
  • Most bacteria feed off other organisms living or dead.
  • EXAMPLES = lactobacillus bulgaricus (rod shaped and used to make milk sour for yogurt) and pneumococcus (spherical in shape)
• • VIRUSES - they are particles rather than cells, and are smaller than bacteria.
  • can only reproduce inside living cells. A virus is an example of a parasite - it depends on another organism to grow and reproduce.
  • they infect all types of living organisms.
  • they come in loads of different shapes and sizes.
  • don't have a cellular structure - they have a protein coat around some genetic material.
  • EXAMPLES: influenza virus , tobacco mosaic virus (leaves tobacco plants discoloured by stopping them from producing chloroplasts) , HIV
• Pathogens are organisms that cause disease. They include some fungi, protoctists and bacteria. Viruses are also pathogens.
• PROTOCTISTS: Plasmodium > malaria

  BACTERIUM: Pneumococcus > pneumonia

  VIRUSES: Influenza Viruses > flu and HIV > AIDS
• Enzymes are biological catalysts produced by living things. Enzymes reduce the need for high temperatures, they just speed up the rate of chemical reactions. They are all proteins (proteins are made up of chains of amino acids). These chains are folded into unique shapes which allow enzymes to do their jobs.
• For the enzyme to work, the substrate must be the correct shape to fit in the active site.
• When you increase the temperature, the enzyme and substrate have more energy and are more likely to collide and form enzyme-substrate complexes.
• If it gets too hot (over 40 celcius ) the bonds holding the enzymes together break which changes the shape of the active site so the substrate won't fit. This enzyme is said to be denatured.
• pH does the same and interferes with the bonds holding the enzyme together which changes the shape of the active site and denatures the enzyme. Normally the optimum pH is 7.
• Diffusion is the met movement of particles from an area of high concentration to an area of low concentration.
• It doesn't require energy and happens in both liquids and gases. The bigger the difference in concentration the faster the diffusion rate.
• Osmosis is the net movement of water molecules through a partially permeable membrane from a region of higher water concentration to a region of lower water concentration