Tag: zoology

The one gene-one enzyme hypothesis is the idea that genes act through the production of enzymes, with each gene responsible for producing a single enzyme that in turn affects a single step in a metabolic pathway. The concept was proposed by George Beadle and Edward Tatum in an influential 1941 paper.  Beadle and Tatum noted that it was "entirely tenable to suppose that these genes which are themselves a part of the system, control or regulate specific reactions in the system either by acting directly as enzymes or by determining the specificities of enzymes".

According to one gene-one polypeptide hypothesis, the information enclosed in one gene is sufficient to form one polypeptide only. Genes control the synthesis of all proteins. Some proteins are enzymes and some are hormones. As we know that proteins are made up of polypeptides- long chains of amino acids. Some proteins consist of two or more polypeptides linked and twisted around each other. For eg, hemoglobin.

AMP is known as Adenosine monophosphate which is involved in many biological processess. It is a type of nucleotide phosphate. It  consists of phospate group and nucleobase adenine. It is used to regenerate ATP.

Producer site produces pre mRNA, which after processing becomes mRNA. Its expression is under the control of many receptor sites. mRNA later takes part in protein synthesis during translation. 

The one gene-one enzyme hypothesis, proposed by George Wells Beadle in the US in 1941, is the theory that each gene directly produces a single enzyme, which consequently affects an individual step in a metabolic pathway. Beadle and Tatum worked with a simple organism: common bread mold, or Neurospora crassa. Using Neurospora, they were able to show a clear connection between genes and metabolic enzymes. With a series of the experiment they first created mutant Neurospora and found which metabolic pathway was broken in mutants by growing them in a variety of nutritional medium. Their work produced a revolution in the study of genetics and showed that individual genes were indeed connected to specific enzymes. 

The most significant limiting factor in high mountain regions is the lower air pressure, which makes it more difficult for oxygen to enter our vascular systems resulting into hypoxia. When we travel to high mountain areas, our bodies initially develop inefficient physiological responses. Then there is an increase in breathing and heart rate to as much as double, even while resting. Pulse rate and blood pressure go up sharply as our hearts pump harder to get more oxygen to the cells. These are stressful changes, especially for people with weak heart. Later, a more efficient response normally develops as acclimatization takes place. Additional red blood cells and capillaries are produced to carry more oxygen. The lungs increase in size to facilitate the osmosis of oxygen and carbon dioxide. There is also an increase in the vascular network of muscles which enhances the transfer of gases.

Babies and children normally breathe faster than older children and adults. Newborn to 6 months: 30-60 breaths/min

• The respiratory system represents the organs that are involved in the exchange of oxygen and carbon dioxide between the organism and the environment.
• In animals, a primary layer of cells is formed during embryogenesis, three in number and are differentiated as ectoderm, mesoderm, and endoderm. The tissues produced by these layers give rise to the organs of the body. 
• The respiratory tract with tracheae, bronchi, alveoli of the lungs is developed from the endoderm. The mesoderm forms the mesothelium from which lines the thoracic cavity and external intercostal muscles.
  Hence, the correct answer is D.