Energy Rich Compounds
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Transcript of Energy Rich Compounds
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The Functions of ATPATP plays a very important role in a living cell. It drives different cellular processes such as synthesis of new chemical compounds, membrane transport, mechanical work and many more.
Read more: http://www.brighthub.com/science/medical/articles/16096.aspx#ixzz1EkeZFJbv
Adenosine Triphosphate, commonly known as ATP, is highly important in all biochemical processes. Without this energy rich compound, cellular metabolism would be so impossible. It is the principal energy source of the cell. The ATP supplies of the cell are usually produced in the mitochondria through the process of oxidative phosphorylation. Cellular activities that need energy spending fall into three common categories, and two rarer ones:
Synthesis of New Chemical Compounds
The endoplasmic reticulum needs ATP to synthesize different important proteins like enzymes which facilitate fast chemical reactions. All cells employ ATP for this general purpose. Some cells, especially cells with high rate of secretion (e.g. salivary and digestive gland cells) and cells in the growth stage (e.g. developing germ cells), use up to 75% of the ATP they generate just to manufacture new chemical compounds (Lehninger 2005).
Membrane Transport
The selective transport of nutrient and mineral molecules across the digestive tract wall requires ATP. Scientists think all cells employ ATP for at least some forms of transport. This can arrive at extremes in specialized transporters such as kidney tubules, which can use up as much as 80% of their ATP currency (Lehninger 2005) to operate their selective membrane transport mechanisms.
Mechanical Work
ATP is needed for the contraction of skeletal and cardiac muscles. The heart must contract in order to pump blood toward the different parts of the body. The skeletal muscles should also contract in order for us to do different physical activities such as lifting an object. These activities entail great amount of ATP.
Bioluminescence
ATP reacts with large carbon-nitrogen molecules (a luciferin) to produce photons in the visible range of wavelength. This use of ATP is somewhat rare on land, but is common in marine organisms, especially in the deep.
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Heat Production
ATP is generally used for the purposes of thermoregulation and other uses of high temperature. This occurs for useful purposes only in a few groups of organisms. Skeletal muscles and special heater tissues convert chemical-bond energy into heat.
As a consequence of cellular energy spending to support these different activities, large amount of ATP are manufactured. These energy-diminished ADP molecules enter the mitochondria for “recharging” and then the cycle back into the cytosol as energy-rich ATP molecules after participating oxidative phosphorylation. A single ADP/ATP molecule may transfer back and forth between the mitochondria and cytosol for this recharging/expenditure cycle thousands of times per day.
The high demands for ATP provide glycolysis alone an inadequate as well as ineffective supplier of power for most cells. If it were not for the mitochondria, which contain the metabolic machinery for oxidative phosphorylation, the energy capability of a cell would be very limited. However, glycolysis does provide at least some ATP under anaerobic conditions.
Reference
Lehninger, Albert. 2005. Principles of Biochemistry. New York : W.H. Freeman
Read more: http://www.brighthub.com/science/medical/articles/16096.aspx#ixzz1Ekeln27c
Nucleotides are nitrogen containing organic compounds, which form the monomers of nucleic acids that are
involved in the information transfer system of the cells. They are also involved in the mechanism of energy
transfer in cells.
A nucleotide is a compound containing carbon, hydrogen, oxygen, nitrogen, and phosphorous. A molecule of a
nucleotide is in turn composed of three smaller molecules phosphate (P) sugar (S) and nitrogen base (N).
The phosphate group is represented by phosphoric acid (H3PO4).
The sugar molecule in the nucleotide is a 5-carbon pentose sugar. It is represented by either ribose
sugar (C5H10O5) or deoxyribose sugar (C5H10O4). Both the sugars have a furanose ring structure.
The nitrogen base is represented by compounds having nitrogen and carbon in the ring structure. Two
types of nitrogen bases occur, namely
a) Purines, which have a double ring structure and
b) Pyrimidines, which have a single ring structure.
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fig. 13.14 - Components of Nucleic Acids
Purines are of two types adenine (A) and guanine (G). Pyrimidines are of three types Cytosine (C), Thymine (T),
and Uracil (U).
fig. 13.15 - Structures of Nitrogenous Bases in Nucleic Acids
The nitrogen base molecule is attached to the sugar molecule by a glycosidic bond. A combination of nitrogen
base with sugar is called as a nucleoside. Nucleosides involving ribose sugars are called ribonucleosides.
Similarly, nucleosides involving deoxyribose sugars are called deoxy ribonucleosides.
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A nucleoside combines with a phosphate group to form a compound called nucleotide. Nucleotides formed by
ribonucleosides are called ribonucleotides. They form the monomers of ribose nucleic acid (RNA). Nucleotides
formed by deoxyribonucleosides are called deoxyribonucleotides. They form the monomers of deoxyribose
nucleic acid (DNA).
fig. 13.6 - Formation of a Nucleotide
The nucleotides which form nucleic acids have only one phosphate group (monophosphates). Each of them can
form a diphosphate and a triphosphate. Linkage of additional phosphate group occurs at the cost of a large
amount of energy. The bonds that join the additional phosphate groups are called as high energy or energy rich
bonds. Separation of these additional phosphate groups from the nucleotides by enzymatic hydrolysis releases
correspondingly large amount of energy. Hence, these higher nucleotides (with one or two additional
phosphates) form energy rich compounds.
Adenine + Pentose Sugar - Adenosine (Adenine Nucleoside)
Adenosine + Phosphate - Adenylic Acid or Adenosine Mono Phosphate (AMP)(Adenine Nucleotide)
Adenosine Monophosphate + Phosphate - Adenosine Diphosphate(ADP)
Adenosine Diphosphate + Phosphate - Adenosine Triphosphate (ATP)
Similarly, for other nitrogen bases.
The nucleotides by combining with other organic compounds or molecules form co-enzymes. For example, NAD
Nicotinamide Adenine Dinucleotide, FAD-Flavin Adenine Dinucleotide.
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Some nucleotides like cyclic AMP function as regulatory chemicals controlling diverse cellular functions.