Lab#2 - Biologically important Molecules Flashcards
Biological Molecules
Organic molecules in living organism are:
- carbohydrates
- proteins
- lipids
- nucleic acids
Organic compounds
• Subunits are linked together by Dehydration synthesis
- remove a water molecule
- energy required
Dehydration synthesis
An energy requiring process in which a molecule of water is removed and subunits are bonded covalently.
Breaking the bond between the subunits of hydrolysis
- Addition of water molecule
* Energy released
Hydrolysis
An energy releasing process that involves breaking the bond between the subunits that requires the addition of water molecule
Characteristic subunits and chemical properties
Subunits of macromolecules are held together by covalent bonds
Different structure and properties
- Lipids have C-H bonds and relatively little oxygen- no polar insolvable water.
- Proteins have amino groups (NH2) and carboxyl group ( -COOH)
Controlled experiments to identify organic compounds
• each test involves two or more treatments:
- An unknown solution to be identified.
- Controls to provide standard for comparison
Positive control
Contains the variable for which you are testing
- positive reaction
- demonstrate the tests ability to detect the compound
Negative control
Does not contained the variable for which you are testing
• no reaction ( only solvent such as distilled water )
Carbohydrates Benedict Reagent test for reducing sugars
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
Carbohydrates Benedict Reagent test for reducing sugars
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
Monosaccharides are reducing sugar
- 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.
Iodine test for starch
- 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.
Proteins
• Proteins are made of amino acids
• Amino acid has
• an amino group
（- NH2）
• a carboxyl group
( -COOH)
• a variable side chain
(-R)
Proteins have polypeptide chain
A peptide bond forms between the amino group one amino acid and the carboxyl group of an adjacent amino acid
Iodine test for starch
- 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.
Proteins
• Proteins are made of amino acids
• Amino acid has
• an amino group
（- NH2）
• a carboxyl group
( -COOH)
• a variable side chain
(-R)
Buiret test for protein
- 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.
Lipids
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.
Lipids
- 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
Electromagnetic spectrum
• the electromagnetic spectrum includes radiation with wavelength from less than 1 to more than 1 million nanometers.
Visible light
- 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.
Buiret test for protein
- 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.
Proteins
• Proteins are made of amino acids
```
• Amino acid has
• an amino group
（- NH2）
• a carboxyl group
-COOH
~~~
Visible light
- 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.
Spectrophotometry
- 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.
Spectrophotometer
- An instrument measures the amount of light absorbs and transmitted by dissolved chemical
- absorbed light
- teams
Spectrophotometer
- 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
Spectrophotometer
- An instrument measures the amount of light absorbs and transmitted by dissolved chemical
- absorbed light
- teams
Spectrophotometer
- 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
Absorbance and transmittance
- 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
Absorption spectrum of methylene blue
- the pattern of wavelength absorbed by a chemical is its “fingerprint” - absorption spectrum
- Representing as a graph relating absorbance to wavelength
