structures and function in living systems

These genes transcribe mRNAs, which are translated by ribosomes and tRNAs into the polypeptides. The latter function as enzymes. The trytophan operon comprises 5 structural genes denoted as E, D, C, B, and ..

In graphite, the carbon atoms are arranged in flat parallel layers as regular hexagons. Each layer is bonded to adjacent layers by weak Van der Waals forces. This allows each layer to slide over the other easily. Due to this type of structure graphite is soft and slippery, and can act as..

Structurally all types of chlorophyll resemble one another. All of them contain four pyrrole rings [also called porphyrin] which are linked together by methane bridges (-CH=). The skeleton of each pyrrole ring is made up of five atoms - four carbon and one nitrogen with magnesium in the c..

6 0 molecule C 6 0 molecule has marvelously symmetrical structure. It is a fused-ring of aromatic system containing 20 hexagons and 12 pentagons of sp 2 hybridized C atoms. The structure bends around and closes to form a soccer ball shaped molecule. C 6 0..

Structure of a Nephron - The nephron or uriniferous tubule is the functional unit of the kidney. A nephron consists of a twisted tubule closed at one end, open at the other with a network of associated blood vessels. Each kidney of man is formed of about one million nephrons. Ea..

External view of a Mammalian Heart The heart is a 4 chambered muscular pump located inside the chest or the thoracic cavity. It is a mesodermal derivative and is a myogenic heart. The heart is surrounded externally by a thin, transparent 2 layered serous sac called pericardium. The narrow cavi..

fig. 19.3 Structure of Chromosomes The terminal end of a chromosome is called as telomere. It is functionally different from the rest of the chromosome. A chromatid may breakup into pieces and the pieces may rejoin, but no segment becomes connected to the telomere. Thus, the tel..

A well developed digestive system which can take care of the energy requirements of the animal is present. It consists of an alimentary canal and associated structures. The buccal cavity contains teeth, which are of three different types : incisors, premolars and molars. Canines..

Functions - The nervous system carries out the following functions i) It perceives the changes around us through our senses. ii) It controls and coordinates all the activities of the muscles in response to the changes outside. iii) It also maintains the internal enviro..

State of the System and State Functions - State of the system implies the conditions of its existence. In order to understand it, let H 2 O be considered as a chemical system. H 2 O can exist in three physical states; ice, water and steam depending upon the c..