Biochemical Miscellaneous

Biochemical Miscellaneous

Easy Questions

Biochemical

Biochemical Miscellaneous
  1. A bacterial culture (200 µl containing 1.8 × 109 cells) was treated with an antibiotic Z (50 µg per ml) for 4 h at 37°C. After this treatment, the culture was divided into two equal aliquots. ​​
    Set A : 100 µl was plated on Luria agar.
    ​​Set B : 100 µl was centrifuged, the cell pellet washed and plated on Luria agar.
    After incubating these two plates for 24 h at 37°C, Set A plate showed no colonies, whereas the Set B plate showed 0.9 × 109 cells. This experiment showed that the antibiotic Z is ​​








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    Bacteriostatic antibiotics limit the growth of bacteria by interfering with bacterial protein production, DNA replication, or other aspects of bacterial cellular metabolism. Since after incubation, plate A showed no colonies and plate B showed 0.9 * 109 colonies (half of the bacterial culture before inoculating), thus it shows that antibiotic Z is bacteriostatic which has stopped the bacteria from reproducing.

    Correct Option: A

    Bacteriostatic antibiotics limit the growth of bacteria by interfering with bacterial protein production, DNA replication, or other aspects of bacterial cellular metabolism. Since after incubation, plate A showed no colonies and plate B showed 0.9 * 109 colonies (half of the bacterial culture before inoculating), thus it shows that antibiotic Z is bacteriostatic which has stopped the bacteria from reproducing.

  1. Match the downstream processes in Group I with the products in Group II. ​​​
    Group I​​ Group II
    ​P.​ Solvent extraction​ 1.​ Lactic acid
    Q. ​Protein-A linked affinity ​ 2.​ Penicillin ​​​chromatography
    R.​ Extractive distillation​ 3.​ Monoclonal antibody ​​
    S.​ Salting out ​ 4.​ Lipase ​​
    ​​








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    Solvent extraction is a method for processing materials by using a solvent to separate the parts. It can be used for penicillin extraction. ​​
    Affinity chromatography is the preferred method of bioselective adsorption and subsequent recovery of a compound from an immobilized ligand. Each is designed for highly specific and efficient purification of proteins and related compounds like monoclonal antibody.
    ​​Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, and the solvent that forms no azeotrope with the other components in the mixture. It can be used for lactic acid recovery. ​​
    Salting out is a purification method that utilizes the reduced solubility of certain molecules in a solution of very high ionic strength. Crude lipase can be purified by using salting out method.

    Correct Option: A

    Solvent extraction is a method for processing materials by using a solvent to separate the parts. It can be used for penicillin extraction. ​​
    Affinity chromatography is the preferred method of bioselective adsorption and subsequent recovery of a compound from an immobilized ligand. Each is designed for highly specific and efficient purification of proteins and related compounds like monoclonal antibody.
    ​​Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, and the solvent that forms no azeotrope with the other components in the mixture. It can be used for lactic acid recovery. ​​
    Salting out is a purification method that utilizes the reduced solubility of certain molecules in a solution of very high ionic strength. Crude lipase can be purified by using salting out method.

  1. ​In an exponentially growing batch culture of Saccharomyces cerevisiae, the cell density is  20 gl–1 (DCW), the specific growth rate (µ) is 0.4h–1 and substrate uptake rate (ν) is 16 gl–1h–1. The cell yield coefficient Yx/s will be ​








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    Yield coefficient = mass of new cells formed / mass of substrate consumed ​​
    New cells mass formed = cell density x specific growth rate = 20 × 0.4 = 8
    ​​Substrate consumed = 16 g/l/h ​​

    Yield coefficient =
    8
    		 = 0.5
    16

    Correct Option: D

    Yield coefficient = mass of new cells formed / mass of substrate consumed ​​
    New cells mass formed = cell density x specific growth rate = 20 × 0.4 = 8
    ​​Substrate consumed = 16 g/l/h ​​

    Yield coefficient =
    8
    		 = 0.5
    16

Direction: During sterilization of a fermentation medium in a given bioreactor ∇heating = 12.56, ∇cooling = 7.48 and the ​total value of ∇ required for whole sterilization process is 52, where ∇ is the design criteria. ​

  1. What is the holding period (min) at a k value of 3.36 min–1? ​








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    Given k value = 3.36 min–1 ​
    Holding value of design criteria, = 31.96
    ​Therefore, time of holding, ​  t = ∇holding / k ​​​
    = 31.96 / 3.36 min = 9.512 min.

    Correct Option: B

    Given k value = 3.36 min–1 ​
    Holding value of design criteria, = 31.96
    ​Therefore, time of holding, ​  t = ∇holding / k ​​​
    = 31.96 / 3.36 min = 9.512 min.

  1. What is the value of ∇holding? ​​








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    Given,  ∇heating = 12.56,  ∇cooling = 7.48 ​
    Now we have,  ∇total = ∇heating + ∇cooling + ∇holding
    ⇒ ​​​52 = 12.56 + 7.48 +​ ∇holding
    ⇒  ​​  ∇holding = 31.96  

    Correct Option: A

    Given,  ∇heating = 12.56,  ∇cooling = 7.48 ​
    Now we have,  ∇total = ∇heating + ∇cooling + ∇holding
    ⇒ ​​​52 = 12.56 + 7.48 +​ ∇holding
    ⇒  ​​  ∇holding = 31.96