Topic 1 - The Nature and Variety of Organisms

• What are the characteristics for living beings?


  M - movement

  R - respiration

  S - sensitivity

  C - control

  G - growth

  R - reproduction

  E - excretion

  N - nutrition
• examples of nutrition


  fats, carbohydrates, vitamins, minerals
• Eukaryote


  Contain a nucleus, distinct membrane, both single + multi-cellular
• Prokaryotic


  No nucleus, single-celled

  The nuclear material found in cytoplasm
• 5 kingdoms


  animal, plants, fungi, protoctists, prokaryotes
• Animal cells


  - multicellular

  - eukaryotes

  Includes: cell membrane, nucleus, ribosomes, mitochondria, cytoplasm
• Levels or organisation


  Organelles, cells, tissues, organs, organ systems, organism
• Plant cells


  - multicellular

  - eukaryotes

  Includes: cell membrane, cell wall, cytoplasm, mitochondria, ribosome, large permanent vacuole, nucleus, chloroplasts
• Function of nucleus


  an organelle which contains the genetic material (DNA) that controls the activities of the cell
• Function of cytoplasm


  a gel-like substance that keeps organelles protected and provides structure for them. also where chemical reactions take place. It has enzymes that control these reactions.
• Function of cell membrane


  dictates what substances goes in and out of cell, outer surface of cell (structure)
• Function of ribosomes


  In charge of protein synthesis (where they are made)
• Function of mitochondria


  Most reactions for aerobic respiration takes place here. This is used to fuel cellular processes. Higher mitochondria count = higher metabolism
• What do plants have that animal cells dont?

  Large permanent vacuole, cell wall, chloroplasts
• Function of vacuole


  Contains cell sap (solution of sugars and salts). It's used for storage of water and minerals (as plants cannot move). It also supports the shape of the cell.
• Function of cell wall

  A rigid structure made of cellulose. It supports and strengthens the cell.
• Function of chloroplast


  Contains green chlorophyll pigment which absorbs light energy needed for photosynthesis. Also contains other enzymes use for that process.
• What are the plant cell walls made of?

  cellulose
• What are the fungi cell walls made of?

  chitin
• What are the bacteria cell walls made of?

  peptidoglycan
• Fungi


  - Mostly multi-cellular (but some single)

  - Most have bodies called mycelium made of hyphae. Hyphae has a thread-like structure and many nuclei.

  - Eukaryotes

  - No chloroplast = no photosynthesis

  - Feed via saprotrophic nutrition

  - no nervous coordination

  Includes: nucleus, cell membrane, cell wall, ribosomes, cytoplasm, mitochondrion
• What do fungi store carbohydrates as?

  glycogen
• Saprotrophic nutrition


  This is how fungi feed. They secrete extracellular digestive enzymes outside their body (outside the mycelium) onto the food (mostly decaying organisms) and absorb the digested molecules.
• Examples of fungi


  Yeast, mushrooms, mould
• Protoctists


  - eukaryotic

  - single-celled and microscopic

  - distinct membrane

  - some have features like cell walls and chloroplasts (photosynthesise) like plants, OTHERS don't

  - no nervous coordination

  MAY include: nucleus, food vacuole, ribosomes, cell membranes, mitochondrion, cytoplasm, chloroplast
• Example of protoctists


  Amoeba, chlorella
• Bacteria


  - Prokaryotic

  - Microscopic, single-celled

  - No nucleus but have circular chromosomes of DNA

  - Some can photosynthesise (even with no chloroplast as they have chlorophyl enzymes)

  - Some feed off other organisms (living + dead)

  - NO MITOCHONDRIA

  Include: cytoplasm, ribosome, plasmids (small circular loops of DNA containing gene), circular chromosomes of DNA, cell membrane, cell wall
• Pathogen


  A microorganism that causes disease in other organisms
• Pathogen examples


  Bacteria, fungi, protoctists, viruses

  (note that not all species within these groups are pathogens. Many bacteria are harmless for example)
• Viruses


  NON-LIVING PATHOGENS

  - Parasite -> depends on another organism to grow and reproduce

  - Can only reproduce inside living cells

  - No cellular structure

  - Protein coat around genetic material (DNA/RNA)
• Examples of Viruses


  - Influenza

  - HIV

  - Tobacco mosaic virus (makes leaves of tobacco plant become discoloured by stopping the production of chloroplast).
• Bacteria example


  - Lactobacillus (a rod-shaped bacterium used in the production of yoghurt from milk)

  - Pneumococcus (a spherical bacterium that acts as the pathogen causing pneumonia)
• Enzymes


  - Biological catalyst that speed up chemical reactions without getting used up.

  - Enzymes are proteins comprised of amino acids linked together

  - Made of living cells

  - Enzymes have an active site that are substrate specific. When the enzyme and substrate attach tgth, they form an enzyme-substrate complex
• Enzymes and temperature


  - all enzymes have optimum temperatures (temp where they are most active)

  - at first, rise in temp results in more kinetic energy for molecules to move around. This increases the chance of successful collisions

  - At some point, it gets too hot resulting in the bonds holding the enzyme together to break. This de-natures the enzyme as the active site shape will change.
• Denaturation is irreversible True or False


  True
• Enzymes and pH


  - Each enzyme has an optimal pH (where it is most active)

  - Too high or too low results in the bonds holding the amino acid chain to make up the protein (the enzyme) to break. This denatures the enzyme, changing the shape of the active site
• PRACTICAL: Enzyme activity (temp)

  - Amylase is an enzyme that breaks down starch into maltose

  - Iodine solution detects if starch is present through blue-black colour for positive test

  
  

  1) use water bath and thermometer to control the temperature of the amylase-starch solution

  2) put a drop of iodine in each spotting tile

  3) every min add drop of amylase-starch solution. the colour should start of blue-black as starch is present

  4) repeat until the iodine solution stops turning blue-black. This means that the amylase has broken down the starch into maltose.

  5) record time taken for reaction to be completed + test with other temps
• Independent variable


  thing you change
• dependent variable


  the thing you measure
• control variable


  the thing you keep the same