2.2 Test for biological Molecules Flashcards

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1
Q

steps to reducing sugar test

A

1) Add benedict’s solution to sample
2) Stir it & place in a water bath at 80 degrees for 3 minutes
3) Note colour change

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2
Q

why is there a colour change when testing for reducing sugars

A
  • Reducing sugars gives electrons
  • Reducing sugars give electrons to the Cu2+ ions, turning them into Cu which forms orange/red colour
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3
Q

How to carry out carbohydrate test

A

1) take iodine and add a few drops to the sample
2) If turns black starch is present

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4
Q

why does iodine cause colour change in starch

A
  • The iodine ions forms a triiodide
  • It then slips into helix of amylose and causes colour change
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5
Q

what is the steps for testing for non-reducing sugars

A
  • First test for RS
  • Take a separate sample & boil it with HCL to hydrolyse sucrose into glucose + fructose
  • Cool Solution
  • Add Soduim Hydrogen Carbonate to neutralise it
  • Test for RS
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6
Q

How to carry out test for lipids

A
  • Take a sample & mix throughly with ethanol & shake
  • Filter & add water
  • Cloudy precipitate indicates presence of lipids
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7
Q

How to carry out test for Proteins

A
  • Add buiret solution
  • Forms liliac colour
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8
Q

why does colour change in protein test

A

The colour change is formed due to a complex being formed by the Nitrogen atom in peptide chain and the Cu2+

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9
Q

calorimetry

A

Piece of equipment used to quantitatively measure absorbance or transmission of light by a colored solution.

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10
Q

6 steps to calorimetry

A

Filter is placed in colorimeter.

Calorimeter is then calibrated using distilled water.

Benedict’s test is performed on a wide range of known concentrations of glucose.

Solutions are filtered to remove precipitate

% transmission of each solution is measured.

The calibration curve is then plotted.

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11
Q

what is a biosensor

A

Using biological components to determine the presence and concentration of molecules such as glucose.

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12
Q

3 steps to biosensor

A

1) Molecular recognition: Single strand of DNA or protein which are complementary to test sample is immobilised. When sample is added, it will bind to DNA/protein

2) Transduction: This binding causes change in a transducer, resulting in an electronic current.

3) Display: This current is processed to determine the concentration of sample present.

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13
Q

what is Thin Layer Chromotography

A

Technique used to seperate the individual components of mixture

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14
Q

what is the stationary phase

A

Silicia gel is applied to chromotography paper & then amino acids are then added to one end

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15
Q

what is the mobile phase

A

organic solvent moves up chromotography paper resulting in amino acids moving different distances

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16
Q

7 steps to chromotography

A

Wearing gloves draw a 2cm line from bottom edge.

Mark 4 equally spaced points along the pencil line.

Amino acids are placed on the four dots.

Placed in a jar with a solvent that’s no deeper than 1cm, & the jar is then closed

The plate is left until the solvent has reached 2cm from the top & left to dry

Spray with ninhydrin, which reacts with amino acids to form a purple slash brown color.

Mark each spot with pencil and measure distance