Blacicenn wauld ndicale 2s being produced. n ountuioT (o plIS 24. When a student
ID: 217935 • Letter: B
Question
Blacicenn wauld ndicale 2s being produced. n ountuioT (o plIS 24. When a student added a few drops of H202 to this tube she wrote down positive (+). i. What is the name of this test? (2 points i. What did she observe? (2 points) ili. What is the substrate?And what is the enzyme? (4 points) iv. What will be a negative observation? (2 points) The MacConkey agar plate is used to identify enterics i. What are the inhibitors in this medium? (2 points) 25. li. What sugar is the sole source of carbon in this medium? (2 points)Explanation / Answer
24.
I) The name of the test is ELISA - Enzyme Linked Immunosorbent Assay.
II) She observed a colour-change from colourless to darkish blue.
III) The substrate is H2O2 - Hydrogen peroxide. And the enzyme used is HRP- Horseradish peroxidase.
IV) Negative observation will be a No change in colour.
Explaination: The test ELISA is used to detect the spacificity of Antigen-antibody or other protein molecules. The antigens are made to adhere the surface of the test tube. And then enzyme linked Antibodies are added upon 'em. This is followed by addition of substrate wash. In our case enzyme HRP is linked to antibodies and substrate Hydrogen peroxide is added dropwise upon it. HRP breaks Hydrogen peroxide and the reaction produces detectable colour. In negative result, the antibodies won't be specific to antigens adhered, so the binding won't happen. And when the substrate will be added there will be no enzyme in the test to react with. Thus no colour change.
25.
I) The inhibitors in this medium are Bile salts and CV (Crystal Violet). Both the reagents inhibits the growth of Gram positive bacteria.
II) Lactose is the sole source of carbon in this media. As only gram negative bacteria utilizes it. Thus making it a selective media.
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