Bio Lab Ch 1 & 4

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Bio Lab Ch 1 & 4
2010-07-12 23:41:26
scientific method

Prep for exam on ch 1 & 4. Scientific Method and enzymes
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  1. Hypothesis
    tentatively explains somthing observed (proposes an answer to a question - suggest a possible explanation)

  2. Who found the stricture of DNA?
    Watson & Crick
  3. What are the components of scientific investigation?
    • 1) Ask a question (must be testable - not subjective eg pretty, smart)
    • 2) Develop a hypothesis
    • 3) Design an experiment to test the hypothesis (experimental design)
    • 4) Make a prediction
    • 5) Conduct experiment
  4. What is involved in Experimental Design?
    • 1)Determine All Variables
    • a. Dependent Variable
    • b. Independent Variable
    • c. Controlled Variables
    • 2)Develop a procedure
    • a. Level of Treatment
    • b. Replication
    • c. Control
  5. Dependent Variable
    measured, counted, or observed in response to the experimental conditions
  6. Independent Variable
    experimental condition which is manipulated to test the hypothesis

    *most important variable by which to text the hypothesis*
  7. Controlled Variables

    The variables that must be kept consistant during the experiment
  8. Procedure
    sequence of steps to be performed for the experiment
  9. Level of Treatment
    value set for the independent variable (specifically amount used for the test)

    in some experiments there is no level of treatment
  10. Replication
    procedure should be repeated several times, providing consistant results
  11. Control (control treatment)
    Hold the same (placebo)

    the indenpendent variable is held at established level or omitted. Allows scientist to decide if the effect is really due to the indepentent variable.
  12. Prediction
    If/ then statement

    If the hypothesis is true/ then the results of the experiment will be....
  13. qualitative

    qualitative - subjective - quality such at pretty or smart cannot be measured by science

    quantatative - objective - data - measurable
  14. isometric growth
    growth at the same rate - two body parts grow at the same rate. Proportions between body parts remain constant as the organism grows.
  15. allometric growth
    growth at different rates - parts of an organism grow at different rates
  16. what axis is the independent variable on?
    x axis - horizontal
  17. what axis is the dependent variable on?
    y axis - vertical
  18. Components of a graph
    • 1) Title - clearly tells what graph is about - goes BELOW the graph - Cap first work and period at the end.
    • 2) Key - what the different lines or dots represent
    • 3) X axis labeled - (indedendent variable) what measured and measurement used (oC, cm, mm)
    • 4) Y axis labeled - (dependent variable) what measured and measurement used
    • 5) line of best fit (optional) dont connect the dots
  19. If time is involved in an experiment - what variable is it (normally)?
    independent - x axis
  20. In Lab 1 what was the formula to find the ratio?
    Height/ Body Part = ratio
  21. In lab 1, what was the independent variable? what was the dependent variable?
    Independent was the body part (head circumference)

    Dependent was the ratio H/BP
  22. What is another name for graphs?
  23. What are the primary functions of tables and figures (graphs)?
    1. Help you analyze and interpret your results

    2. Enhance the clarity with which you present the work to your reader
  24. What are the guidelines for making a table?
    • 1. All values of the same kind should read down the column
    • 2. Column headings should include unit of measure (if appropricate)
    • 3. Title - should be clear and concise - Goes at the TOP of the table - cap first word and important period
    • 4. Include replication if appropriate
  25. Line Graph
    Show changes in the quantity of the chosen variable and emphisize the rise and fall of values over their range. ( use to present continuous data)

    • 1. plot data as seperate points
    • 2. use line of best fit (normally) - only connect points when emphesizing changes in the independent (x) variable
    • 3. If more than one set of data - use different colors and include a key
  26. Bar Graph
    Used for data that represents separate or discontinuous groups or non-numerical categories

    Histograms are bar graphs in which the values on the x axis are numbered but grouped together.
  27. What is the essential feature of science that makes it different from other ways of understanding the natural world?
    Science assumes that boilogical systems are understandable and can be explained by fundamental rules or laws
  28. Proteins
    Long chains of amino acids (monomer)
  29. How many different amino acids are there?
  30. How are amino acids joined?
    Peptide bond which is created by dehydration synthesis
  31. Enzyme
    bilogical catalyst - a compound that speeds up a chemical reaction without being used up or altered in the reaction.

    speed up the reaction by lowering the activation energy necessary for the reaction to occur

    Without enzymes most reactions could not happen quickly enough
  32. Do all enzymes have the same shape?
    Each enzyme must have it own specific shape

    Each enzyme can only hold a particular substrate

    Enzymes hold reactants in a particular configuration so that a reaction can occur (lock and Key model)
  33. What is an enzyme made of?
    Enzymes are proteins that are highly specific in function
  34. Substrate
    the material that the catalyst (enzyme) acts upon

    the substrate is modified during the reaction to form a new product
  35. Active Site
    part of the enzyme that binds the substrate (forming the enzyme-substrate complex)
  36. Enzme-substrate complex
    bond of enzyme and substrate

    after the enzyme had done it work the complex disassociates into enzyme and product (or products)
  37. What factors are enzyme activity influenced by?
    environmental factors such as pH & temperature - can change the three-dimensional shape of the enzyme and alter its rate of activity

    enzymes in the human body are designed to work at pH 7 and about 37oC
  38. Activators
    Chemicals that must bind to the enzyme for it to be active (binds and changes it shape)

    example - perms - solution dosent work until activator is applied
  39. Cofactors
    nonprotein substances that bind to the active site of an enzyme and are essential for the enzyme to work
  40. Coenzymes
    organic (biological materials) that are needed for the enzyme to function properly

    many vitamins are coenzymes - if the body is deficient in a certain vitamin then enzymes that need that vitamin will not work right
  41. Inhibitors
    chemicals that shut off enzyme activity

    compeditive and noncompeditive inhibitors
  42. Compeditive inhibitors
    compete with the normal substrate for the active site

    adding more substrate can overwelm the compeditive inhibiter and cause it not to work

    Antifreeze and alcohol
  43. Noncompeditive inhibitors
    binds to some other part of the enzyme - changes the shape (configuration) of the enzyme

    AChE inhibitors - (pestcides causes enzyme processos of insect body to not be able to work)
  44. Two ways to measure enzyme activity
    1. Determine rate of disappearance of the substrate

    2. determine rate of appearance of the product
  45. Describe process of enzyme activity
    • 1. a substrate or substrates bind to the active siteof the enzyme
    • 2. forming the enzyme-substrate complex
    • 3. which then disassociates into enzyme and product or products

    Enzymes can bind substrates together or break them apart
  46. what suffix denotes enzyme?


  47. Catechol oxidase
    enzyme that in the presence of oxygen, causes the removal of electrons and hydrogens from catechol (compound in plant cells). Catechol is converted to benzoquinone (pigment product) and water.

    Catechol + 1/2 O2 →Catechol oxidase→ Benzoquinone + H2O

    this reactions is what causes fruits and vegetables to turn brown when exposed to air
  48. In lab 4 what was the inhibitor that was used?

    how does it work?
    PTU - phenylthiourea

    to be active Catechol oxidase required copper as a cofactor. PTU combines with the copper in the catechol oxidase and inhibits its enzymatic activity

    noncompeditive inhibitor
  49. Amalase
    • enzyme in the saliva of many animals, including humans
    • breaks up starch (polysaccharide) into maltose (disaccaride)
  50. How does starch react when treated with I2KI?
    • Starch turns purple
    • Malose does not react to I2KI
  51. Rate of disappearance
    allows quantatative measure of reaction rate by watching how quickly starch disappears when treated with the enzyme amylase
  52. aliquot
  53. serial dilutions
    take an aliquot (sample) of enzyme and dilute it with an equal amount of water (1:1) Take an aliquot of the dilutution and add to an equal amount of water (1:3) and so on (1:7), (1:15), (1:31)
  54. In the rate of disappearance experiments why is the data graphed in reverse order?
    The deaction rate (the dependent variable) was measured as time of starch disappearance - the highest values indicate the slowest reaction time
  55. Influence of Enzyme concentration on the rate of starch digestion
    Independent Variable
    Dependent Variable
    • Independent - Enzyme concentration
    • Dependent - Reaction rate (time of starch disappearance)
    • As the enzyme amylase concentration is resuced, reaction times get slower and slower until there is no reaction because there is not enough amylase
  56. Effect of pH on amylase activity
    Independent Variable
    Dependent Variable
    • Independnet - pH
    • dependent - Recation rate (in seconds)
    • Each enzyme has a pH range that it works best at (pH can affect the three-dimensional shape of the the enzyme). Amylase works best at pH near 7 and slower at lower and higher pH (bell shaped graph)
  57. Effect of temperature on chemical reactions
    chemical reactions accelerate as temp rises - increased temp speeds up motion of molecule

    10o rise in temp will result in two to three fold increase in reaction
  58. Effect of Temperature on Amylase Activity
    Independent Variable
    Dependent Variable
    • Independent - Temperature
    • Dependent - Reaction Rate
    • Enzyme have an optimal temp that they work best at. Amylase works best near 37oC. It does not work at 4o or 80o (bell shaped graph)
    • High Temperature can cause the integrity of the protein to be permanently denatured.