30 Questions
What is the pH optimum for pepsin?
1.0-2.0
What is the role of N-acetylglutamate in the urea cycle?
Activator of urea synthesis
Which enzyme is formed from trypsin?
Chymotrypsin
What is the end product of protein digestion in the G.I.T.?
Amino acid
What is the optimal pH for the enzyme rennin?
8.0
What is the substance required for the conversion of pepsinogen to pepsin?
HCL
Where are the main sites for oxidative deamination located?
Liver and kidney
In which cellular component are the enzymes of urea synthesis found?
Both mitochondria and cytosol
What is the role of N-acetyl glutamate in urea synthesis?
An enzyme activator
Which enzyme is responsible for controlling the urea cycle?
Carbamoyl phosphate synthetase
What is the major end product of protein nitrogen metabolism in humans?
Urea
What is the primary role of ceruloplasmin in the body?
Transporting copper from the intestinal cells to the liver
Which of the following statements is correct about sodium and chloride?
They are primarily involved in maintaining osmotic equilibrium and body fluid volume
How is NH3 detoxified in the brain?
Converted to glutamate
What is the primary source of natural fluoride?
Water
Which mineral is involved in the enzyme-controlled energy-yielding reactions of metabolism?
Phosphorus
Which mineral is required as a compound of blood hemoglobin?
Iron
What can enhance the absorption of iron from a breakfast of cereal?
Orange juice
Which ion is essential for the development of sound teeth with resistance to tooth decay?
Fluoride ion
Which of the following is necessary for the clotting of blood and functions of certain enzymes?
Calcium
Which vitamin is essential for the absorption of calcium from the intestinal tract?
Vitamin D
What is the consequence of chronic consumption of excess selenium?
brittle hair and nails
What is the role of mineralocorticoids in the body?
Increase the tubular secretion of Sodium
What is the function of manganese in the body?
both (a) and (b)
Where does protein digestion begin in the human body?
Stomach
What is the correct sequence of the antisense RNA corresponding to the mRNA sequence 'ATP'?
5'-UACAAAUCGCGG-3'
Which enzyme is responsible for forming phosphodiester bonds between Okazaki fragments during DNA replication?
DNA ligase
What is the function of ubiquitin in a cell?
It is a short peptide sequence that marks proteins for degradation
In which step of protein digestion does hydrochloric acid play a role?
Activating trypsinogen
Where is ubiquitin found in cells?
In both prokaryotes and eukaryotes
Study Notes
Digestive Enzymes
- Pepsin is formed from pepsinogen by the action of HCL, and its optimum pH is 1.0-2.0.
- Chymotrypsin is not formed from trypsin, and its optimum pH is around 7.
- Trypsin is formed from trypsinogen by enterokinase, and its optimum pH is 8-9.
- Rennin's optimal pH is 2.0-4.0.
Protein Digestion
- Pepsin acts on denatured proteins to produce proteoses and peptones.
- Trypsin hydrolyses peptide bonds involving basic amino acids.
- Chymotrypsin hydrolyses peptide bonds involving aromatic amino acids.
- Elastase is an endopeptidase that hydrolyses peptide bonds involving non-polar amino acids.
Urea Synthesis
- The enzymes of urea synthesis are found in both mitochondria and cytosol.
- N-acetylglutamate is an activator of carbamoyl phosphate synthetase in urea synthesis.
- Carbamoyl phosphate synthetase is controlled by N-acetylglutamate.
- Ornithine transcarbamoylase catalyzes the transfer of the carbonyl moiety from carbamoyl phosphate to ornithine.
Minerals and Vitamins
- Copper is involved in the enzyme-controlled energy-yielding reactions of metabolism.
- Iron is involved in hemoglobin synthesis and is aided by copper.
- Calcium is involved in blood clotting, functions of certain enzymes, and control of fluids through cell membranes.
- Phosphorus is involved in energy-yielding reactions, protein synthesis, and nucleic acid synthesis.
- Vitamin D is essential for the absorption of calcium from the intestinal tract.
- Fluoride is essential for the development of sound teeth with resistance to tooth decay.
Other
- Selenium deficiency leads to liver necrosis.
- Chronic consumption of excess selenium can lead to brittle hair and nails.
- Manganese is needed for normal bone structure and reproduction and functioning of the central nervous system.
- Egg is rich in cholesterol, saturated fatty acids, and calcium, but is deficient in vitamin C.
Test your knowledge of biochemistry with this quiz on enzymes, metabolic pathways, and their mechanisms. Questions cover topics such as urea synthesis, pepsin, and pancreatic juice.
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