Question
Which one of the following pairs of chemical substances, is correctly categorised?
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Calcitonin and thymosin - Thyroid hormones
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Pepsin and prolactin - Two digestive enzymes secreted in stomach
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Troponin and myosin - Complex proteins in striated muscles
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Secretin and rhodopsin - Polypeptide hormones
Solution
C.
Troponin and myosin - Complex proteins in striated muscles
Striated muscle consists of large number of muscle fibres called myofibrils. Myofibrils are made up of actin and myosin protein. The actin or secondary myofilaments also possess troponin and tropomyosin protein.
Thymosin hormone is secreted from thymus gland. Prolactin is a hormone secreted from anterior lobe of pituitary.
Rhodopsin is a pigment found in rod cells of eye.
