Biology for Health (BIOL 5)

• Scientific Method


  Systematic approach in pursuit of truth based on rationality and logic
• Hypothesis


  Intelligent/educated guess to a certain problem
• Types of hypotheses


  • Descriptive hypothesis - overall statements which provides basis for prediction
  • Explanatory hypothesis - statements tend to guess what caused the pattern under observation
• Theory


  Set of related hypotheses supported by many observations and experiment
• Law


  Theory had been tested repeatedly and not proven false
• Experiment


  1. Controlled method of testing a hypothesis

  2. Designed to provide an opportunity to make observation that will help test a hypothesis
• Types of variables in an experiment

  • Independent variables (input) - purposely altered between trials
  • Dependent variables (output) - change in response to the independent variable
  • Controlled variables - kept constant through all of the trials
• A variable can be measured
• Trials are the repetitions with slight variations
• Physical Change


  Molecules move from one physical state of matter (solid, liquid, or gas) to another physical state, no change in the atomic structure, and a new substance is not created
• Chemical Change


  The atomic structure of a substance changes, considered irreversible and a new substance is formed
• Signs of chemical change

  • Formation of gas (bubbles)
  • Change in color
  • Change in pH
  • Change in temperature (increase or decrease)
  • Formation of new solid or liquid
  • Appearance of light
  • Production of electricity
• Iodine test


  Determines the presence of starch
• Benedict's test


  Determines the presence of simple sugars or carbohydrates
• Biuret test


  Determines the presence of proteins
• Biomolecules


  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Starch - Iodine Test

  Positive result: blue-black purple or purple tint appears, long chain of polysaccharides traps the iodine resulting to dark violet complex formation

  Negative result: no color change (brown/yellow) shows lack of starch, brown color of iodine remains monosaccharides unable to trap iodine
• Sugars - Benedict's Test


  Positive result: green to dark red (brick) or rusty brown depending on the amount and type of sugar

  Negative result: no color change (blue)
• Reducing sugar


  A simple carbohydrate with free aldehyde or ketone group and acts as a reducing agent, includes glucose, fructose, glyceraldehyde, lactose, arabinose, maltose, etc.
• Types of carbohydrates


  • Monosaccharides - simplest units of carbohydrates, glucose, fructose, galactose
  • Disaccharides - made by linking monosaccharides, lactose, maltose, sucrose
  • Polysaccharides - complex carbohydrates, starch, cellulose, glycogen
• Proteins - Biuret's Test

  Positive result: existence of proteins when the color of the solution turns purple, existence of peptides (short chains of amino acid residues) when the color of the solution turns pink

  Negative result: no color change (blue) shows lack of protein
• Lipids - Sudan III or IV

  Positive result: solution has 2 layers and the top layer is red/orange or red/orange fat droplets under the microscope

  Negative result: clear solution or 1 layer of evenly distributed red/orange solution, no droplets show lack of lipids
• Microscope


  Optical instrument used for viewing very small objects such as mineral samples or animal or plant cells, typically magnified several hundred times, light passes through the object being viewed, and image is enlarged by a series of lenses
• Compound Light Microscope


  Uses compound lens system, the objective lens is compounded by the eyepiece lens to obtain a high magnification, results to two-dimensional images, most commonly used in observing biological samples in the lab including cells, particles, and prepared slides
• Types of microscopes


  • Darkfield, Phase contrasts, Fluorescence, Confocal, Electron, Dissecting
• Magnification


  Number of times an object is enlarged or reduced, always put an X after the number to denote magnification
• Total Magnification


  Combination of magnification of objectives and the eyepiece
• Parts of the microscope and their functions

  • Mechanical - support and adjust the optical and illuminating parts

  Optical - consists of the parts with lenses aligned on the optical axis for the magnification of the specimen

  Illuminating - used to illuminate the object or specimen
• Unit Conversion - Sample Computation

  1 mm = 1000 μm

  1. 9.3 mmm = 9,300 μm
  2. 1950 mm = 1,950,000 μm
  3. 403 mm = 403,000 μm
  4. 3550 μm = 3.55 mm
  5. 673 μm = 0.673 mm
  6. 11 μm = 0.011 mm
• Cell Size - Sample Computation (μm / cell)

  Low Power Field (LPF): What is the approximate size of a single bacterium in micrometers (μm) if there are approximately 350 cells of a certain bacteria that fit across the LPF (3,000 μm)?

  High Power Field (HPF): What is the HPF of your microscope in μm if it has a LP magnification of 60X, a HP magnification of 600X, and LPF of 1,200 μm?
• Prokaryotic Cells


  1st to evolve, "pro" - before, has a semi-rigid cell wall, no membrane bound organelles (simple structure), unicellar, (Kingdon Archaebacteria and Eubacteria)
• Eukaryotic Cells


  Evolved about 2.1 billion years ago (fossil evidence), "eu" - true, "karyon" - nucleus, has membrane bound organelles with special functions, multicellular/complex of many cells, (Kingdoms Protista, Fungi, Plantae, and Animalia)
• Key Differences between Prokaryotic and Eukaryotic Cells

  • Nucleus - Absent in Prokaryote, Present in Eukaryote

  Membrane-bound organelles - Absent in Prokaryote, Present in Eukaryote

  Cell structure - Unicellular in Prokaryote, Mostly multicellular, some unicellular in Eukaryote

  Cell size - Smaller (0.1-5 μm) in Prokaryote, Larger (10-100 μm) in Eukaryote

  Complexity - Simpler in Prokaryote, More complex in Eukaryote

  DNA Form - Circular in Prokaryote, Linear in Eukaryote

  Examples - Bacteria, archaea in Prokaryote, Animals, plants, fungi, protists in Eukaryote
• Eukaryotic Cell Types


  • Plant Cell - Have plastids (e.g. chloroplast), Have a cell wall (cellulose), Have a large central vacuole, Store excess glucose as starch, Have a plasmodesmata, Do not have centrioles, Do not have cholesterol in cell membrane, Generally, have a fixed, regular shape

  Animal Cell - Do not have plastids, Do not have a cell wall, Have a small temporary vacuole (if any), Store excess glucose as glycogen, Do not have a plasmodesmata, Have centrioles, Have cholesterol in cell membrane, Generally, have an amorphous shape
• Iodine solution on onion cells

  Iodine binds to starch in the granules and develops blue-black color, makes the onion cells clearly visible, confirms that onion stores reserve food material in the form of starch
• Methylene blue on cheek cells

  Methylene blue stains negatively charged molecule cells, cells seen are squamous epithelial cells, the small blue dots are bacteria from our teeth and mouth
• Hydrilla leaf cells on water


  Some plant cells can be seen clearly when mounted in water, cytoplasmic streaming/cyclosis - directed flow of cytosol and organelles around the plant cells, helps in transport of organelles, nutrients, genetic information, metabolites and other materials to the entire part of the cell, caused by the microfilaments