Advanced Botany

  The nif genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to living organisms. They are found in nitrogen-fixing bacteria.  They occur as an operon (a segment of DNA containing adjacent genes including structural genes, an operator gene and a regulatory gene; thus a functional unit of transcription and genetic regulation) in free-living anaerobic nitrogen-fixing bacteria such as  Klebsiella pneumoniae ,  Rhodospirillum rubrum , and  Rhodobacter capsulatus . These genes may also be found on plasmids in symbiotic bacteria, such as in Rhizobium inhabiting the roots of leguminous plants.  Functions nif genes encode an important enzyme, nitrogenase complex which is in charge of converting atmospheric nitrogen (N2 ) to usable form of nitrogen such as ammonia. Nitrogen fixation is important because many living organisms are unable to metabolize directly the atmospheric nitrogen and...

  Ribulose bisphosphate carboxylase/oxygenase ( Rubisco ) is a key enzyme in photosynthesis catalyzing corbon dioxide fixation. Rubisco is ubiquitus for photosynthetic organisms and is regarded as the most abundant protein on earth. More than 90% of the inorganic carbon that is converted into biomass is fixed by the enzyme RubisCO that catalyzes the carboxylation and cleavage of ribulose-1,5-bisphosphate (RuBP) into two molecules of 3-phosphoglycerate (3PG). RubisCO is found in all three domains of life: bacteria, archaea and eukaryotes. The enzyme makes up 30-50% of the soluble protein in plant leaf. Structure Rubisco enzymes are multimeric having two different types of subunits catalytic large (L, 50–55 kDa), and small (S, 12–18 kDa) subunits. Different molecular forms of Rubisco are distinguished by the presence or absence of the small subunit. The most common form (form I) of Rubisco is composed of large and small subunits in a hexadecameric structure, L8S8. This form is presen...

  A biosensor is defined as a device that produces a measurable signal proportional to the concentration of the target analyte, usually incorporating a biological sensing element and measuring signals derived from biological interactions. Biosensors  are self-contained integrated analytical devices that convert a biological response into quantifiable and processable signals. Biosensors required for measurement should have rapid detection, be accurate, be easy to operate, have a low response time, and be low-cost, highly sensitive, and reliable. Working Principle of Biosensors Biosensors are operated based on the principle of signal transduction. These components include a bio-recognition element, a biotransducer and an electronic system composed of a display, processor and amplifier. The bio-recognition element, essentially a bioreceptor, is allowed to interact with a specific analyte. The transducer measures this interaction and outputs a signal. The intensity of the sign...

  Bioenergetics is the branch of biochemistry that focuses on how cells transform energy, often by producing, storing or consuming adenosine triphosphate (ATP). Bioenergetic processes, such as cellular respiration or photosynthesis, are essential to most aspects of cellular metabolism, therefore to life itself. Bioenergetic processes, such as cellular respiration or photosynthesis, are essential to most aspects of cellular metabolism, therefore to life itself. Cellular Respiration  Cellular respiration refers to a catabolic process that cells use to harvest energy from biomolecules. Here, a series of reactions break up macromolecules into their basic units, transforming the potential energy embedded in the chemical bonds into ATPs and the cofactor  nicotinamide adenine dinucleotide (NAD+). Cellular respiration in most organisms takes place in the presence of oxygen ( aerobic respiration),   consisting of the following pathways: Glycolysis ( Embden–Meyerhof–...

Bioenergetics is the branch of biochemistry that focuses on how cells transform energy, often by producing, storing or consuming adenosine triphosphate (ATP). Bioenergetic processes, such as cellular respiration or photosynthesis, are essential to most aspects of cellular metabolism, therefore to life itself. Laws of Bioenergetics 1. Living cells use energy carriers The first bioenergetics law states that living cells do not use the acquired energy directly. Instead, the energy received from external sources is first converted into energy carriers before performing cellular works. Three energy carriers are known to date: Adenosine triphosphate (ATP) Considered the  molecular currency,  ATP consists of adenine attached to one molecule of ribose sugar at carbon one and a triphosphate group at carbon five, where energy is stored in the phosphoanhydride bonds. Energy is released when the triphosphate group of the ATP is broken up into di- and monophosphate, r...