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Biology 171 > Lab#2 - Biologically important Molecules > Flashcards

Lab#2 - Biologically important Molecules Flashcards

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1
Q

Biological Molecules

A

Organic molecules in living organism are:

  • carbohydrates
  • proteins
  • lipids
  • nucleic acids
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2
Q

Organic compounds

A

• Subunits are linked together by Dehydration synthesis

  • remove a water molecule
  • energy required
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3
Q

Dehydration synthesis

A

An energy requiring process in which a molecule of water is removed and subunits are bonded covalently.

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4
Q

Breaking the bond between the subunits of hydrolysis

A
  • Addition of water molecule

* Energy released

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5
Q

Hydrolysis

A

An energy releasing process that involves breaking the bond between the subunits that requires the addition of water molecule

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6
Q

Characteristic subunits and chemical properties

A

Subunits of macromolecules are held together by covalent bonds

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7
Q

Different structure and properties

A
  • Lipids have C-H bonds and relatively little oxygen- no polar insolvable water.
  • Proteins have amino groups (NH2) and carboxyl group ( -COOH)
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8
Q

Controlled experiments to identify organic compounds

A

• each test involves two or more treatments:

  • An unknown solution to be identified.
  • Controls to provide standard for comparison
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9
Q

Positive control

A

Contains the variable for which you are testing

  • positive reaction
  • demonstrate the tests ability to detect the compound
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10
Q

Negative control

A

Does not contained the variable for which you are testing

• no reaction ( only solvent such as distilled water )

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11
Q

Carbohydrates Benedict Reagent test for reducing sugars

A

Carbohydrates are of C,H, + O in a ratio of 1:2:1

  • Monosaccharides- simple sugars
    * Glucose fructose
  • Disaccharides
    • sucrose ( table sugar)

• Polysaccharides
Starch, glycogen, and cellulose

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12
Q

Carbohydrates Benedict Reagent test for reducing sugars

A

Carbohydrates are of C,H, + O in a ratio of 1:2:1

  • Monosaccharides- simple sugars
    * Glucose fructose
  • Disaccharides
    • sucrose ( table sugar)

• Polysaccharides
Starch, glycogen, and cellulose

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13
Q

Monosaccharides are reducing sugar

A
  • Reducing sugar daddy posses free aldehyde(-CHO) or ketone (-C=O) groups that reduce weak oxidizing agents.
  • Benedict’s reagent contains cupric ( copper) ion complexed with citrate In alkaline solution.
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14
Q

Iodine test for starch

A
  • iodine-potassium iodide l2KI
  • starch is cooked polymer of glucose.
     * iodine interacts with coiled molecules and becomes bluish black.
 * Negative ( no reaction) - yellowish brown
  • To distinguish starch from monosaccharide,disaccharides, and other polysaccharides.
    • Glycogen ( in animals) has slightly different structure and produces an intermediate color reaction.
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15
Q

Proteins

A

• Proteins are made of amino acids

• Amino acid has 
   • an amino group
       （- NH2）
    • a carboxyl group 
      ( -COOH)
    • a variable side chain
       (-R)
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16
Q

Proteins have polypeptide chain

A

A peptide bond forms between the amino group one amino acid and the carboxyl group of an adjacent amino acid

17
Q

Iodine test for starch

A
  • iodine-potassium iodide l2KI
  • starch is cooked polymer of glucose.
     * iodine interacts with coiled molecules and becomes bluish black.
 * Negative ( no reaction) - yellowish brown
  • To distinguish starch from monosaccharide,disaccharides, and other polysaccharides.
    • Glycogen ( in animals) has slightly different structure and produces an intermediate color reaction.
18
Q

Proteins

A

• Proteins are made of amino acids

• Amino acid has 
   • an amino group
       （- NH2）
    • a carboxyl group 
      ( -COOH)
    • a variable side chain
       (-R)
19
Q

Buiret test for protein

A
  • Biuret reagent is 1% solution of CuSO4 ( copper sulfate).
  • Peptide bonds (C-N bonds) in proteins complex with Cu2+ in Biuret reagent and produce a violet color- positive reaction.
  • A Cu2+ must complex with four to six bonds to produce a color
  • individual amino acids do not react positively.
  • Long chain polypeptides( proteins) have many peptide bonds and produce a positive reaction - intensity of color relates to the number of peptide bonds.
20
Q

Lipids

A

Lipids dissolve in no polar solvents,but not in polar solvent.

  • ether, acetone, methanol, ethanol
  • water

• Triglycerides ( fats) are made of glycerol and three fatty acids.

21
Q

Lipids

A
  • Sudan IV TEST
    • lipids can selectively absorb pigments in fat-solvable dyes.
  • Grease-spot test
    • lipid can produce translucent grease marks on unglazed paper- such as brown wrapping paper
22
Q

Electromagnetic spectrum

A

• the electromagnetic spectrum includes radiation with wavelength from less than 1 to more than 1 million nanometers.

23
Q

Visible light

A
  • Visible light represents a small part of the electromagnetic spectrum
  • it occurs between 380-700 nanometers (nm)
  • Different materials absorb and reflect different wavelengths of light - show different color.
    • A red object reflects red wavelengths to your eye and absorbs the other wavelengths.
24
Q

Buiret test for protein

A
  • butter reagent is 1% solution of CuSO4 ( copper sulfate).
  • Peptide bonds (C-N bonds) in proteins complex with Cu2+ in Biuret reagent and produce a violet color- positive reaction.
  • A Cu2+ must complex with four to six bonds to produce a color
  • individual amino acids do not react positively.
  • Long chain polypeptides( proteins) have many peptide bonds and produce a positive reaction - intensity of color relates to the number of peptide bonds.
25
Q

Proteins

A

• Proteins are made of amino acids

```
• Amino acid has
• an amino group
（- NH2）
• a carboxyl group
-COOH
~~~

26
Q

Visible light

A
  • visible light represents a small part of the electromagnetic spectrum
  • it occurs between 380-700 nanometers (nm)
  • DIfferent materials absorb and reflect different wavelengths of light - show different color.
27
Q

Spectrophotometry

A
  • A precise technique for the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength.
  • Based on the principle that every different atom a molecule, or chemical bond absorbs unique wavelengths of light.
  • Each chemical has a unique pattern or “fingerprint” of various wavelengths that is absorbs and reflects.
28
Q

Spectrophotometer

A
  • An instrument measures the amount of light absorbs and transmitted by dissolved chemical
    • absorbed light
    • teams
29
Q

Spectrophotometer

A
  • light source- to provide white light
  • filter - to elect the wavelength that you wish to pass through the sample
  • sample- is the solution contained in a clear test tube or cuvette
  • blank- is a test tube or cuvette containing only the solvent
  • Photodetector- A Dexter the transmitted light and convert light energy into extricate energy
  • meter - measure the electrical current and display the absorbance or transmittance values
30
Q

Spectrophotometer

A
  • An instrument measures the amount of light absorbs and transmitted by dissolved chemical
    • absorbed light
    • teams
31
Q

Spectrophotometer

A
  • light source- to provide white light
  • filter - to elect the wavelength that you wish to pass through the sample
  • sample- is the solution contained in a clear test tube or cuvette
  • blank- is a test tube or cuvette containing only the solvent
  • Photodectoror A Dexter
32
Q

Absorbance and transmittance

A
  • Absorbance is the amount of radiation retained by the sample.
  • transmittance is the amount of radiation passing through the sample.

Percentage transmittance = ( lt/l0) x 100
Where lt = transmitted ( exiting ) light intensity
l0 = original ( entering) light intensity

absorbance= log10 (l0/lt)

  • Logarithm of the reciprocal or transmittance
  • absorbance value is proportional to the concentration of substance in the solution.
  • E.g twofold increase in absorbance indicates a twofold increase in concentration
33
Q

Absorption spectrum of methylene blue

A
  • the pattern of wavelength absorbed by a chemical is its “fingerprint” - absorption spectrum
  • Representing as a graph relating absorbance to wavelength

Biology 171 (1 decks)

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