Biology

BIOLOGY 7

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In order to define life, scientists and biologists came up with acriteria upon which every organism must fulfil in order to beclassified as having life. The characteristics that form up thecriteria have come to be known as the properties of life. The sevenproperties of life have been identified as being common amongst allliving things. To start with, scientific research has found out thatliving things are made up of cells. The organisms may have a singlecell or may be having numerous cells (Starr, 2009). The single cellorganism or the unicellular organisms have been identified as beingself-sufficient. Amoeba is a perfect example of a single celledorganism that thrives and survives as a unicellular. Growth isanother primary property of living organisms. All living thingsexhibit some form of growth, be it quick or slow. Growth may occurphysically or cognitively and in most cases in both aspects (Starr,2009).

Although reproduction may not be necessary for survival, it is oneof the most significant element of life. Reproduction is a propertyof life that enables life to continue. Within any living organism arenumerous chemical reactions that occur in order to produce energy forthe organism. Metabolism has been the largely adopted term for thechemical reactions that result in the production of energy (Starr,2009). It is evident that the environment keeps changing in terms ofaspects such as temperature and potential hydrogen. In this regard,living organisms must regulate such changes internally. Therefore,homeostasis as a property of life, is a process that ensuresthat an organism is able sustain a stable internal body status,despite the external environmental changes.

In order to sustain stable internal conditions, living organismsmust be able to respond to the various changes that occur in theirexternal environment. Such changes may include changes intemperature. These responsiveness is one of the properties of lifethat living organisms possess. Some living organisms may engage inshivering when the temperatures are extremely low. Adaptation is thelast, but equally crucial property of life. Living things must adaptto the ever changing environment in order to survive (Starr, 2009).It is evident that some organisms are adapted to survive in differentenvironments. For instance, fish are adapted to survive in water.

The carbon based life on earth is composed of molecules. Whereaslife on earth may seem complex, biological research has indicatedthat life is made up of identical molecules. There are four criticalmolecules that are necessary for life. They are carbohydrates,proteins, lipids and nucleic acids (Starr, 2009). These moleculesamong others constitute a cell. It is worth noting that a cell ismade of millions of cells and other components that enable it tosustain and carry the properties of life. Besides molecules, thereare other components in a cell such as water and inorganic ions.These are components that are vital for life. Water constitutes thelargest part of a cell with over 70% of the total mass of a cell.Water is extremely critical for the development of the cell membrane(Starr, 2009).

Carbohydrate molecules in a cell are extremely vital for life. Thesemolecules contain simple sugars such as glucose which comprise theprimary source of nutrients to the cells. As discussed earlier,production of energy is one of the properties of life. The simplesugars and the polysaccharides are the major sources of cellularenergy hence necessary for life. Lipid molecules are essential forlife and are major compounds in a cell (Starr, 2009). Lipids form thecell membrane which is a vital part of the cell. It is also worthnoting that lipid molecules act as messenger molecules where theytransmit signals from the surface of the cell to within the cell. Anexample of lipids are the fatty acids. These are long form of lipidswhich constitute 16 or 18 carbon atoms.

Proteins and nucleic acids are also two major molecules thatconstitute a cell and give it the attributes of life. Proteins existin several thousand forms inside every cell. They are one of themolecular components of a cell that has extremely critical functions.One of the most significant function of proteins is their ability toact as enzymes inside the cell and therefore catalyze all chemicalreactions. Protein molecules also act as transporters inside thecell. For instance, hemoglobin is responsible for the transportationof oxygen. It is evident that oxygen is extremely necessary for lifein a cell. Antibodies that defend the cell against diseases also areprotein molecules. Nucleic acids Deoxyribonucleic acid (DNA) andribonucleic acid (RNA) are the primary molecules that carry out thefunction of information transmission in cells. DNA is found in everycell of living organism. The two strands of DNA are found in thechromosomes and they form the genetic code of organisms (Sherwood,2010). The division of any cell results in the transmission of DNAinstructions. They are also passed from one generation to anotherhence sustaining life. On the contrary, the ribonucleic acid (RNA)consists of only one strand of nucleotides. RNA is used in the makingof proteins and can also act as an enzyme.

Cell respiration is a process through which glucose in a cell isbroken down in two steps glycolysis and aerobic respiration torelease water, carbon dioxide and energy in form of ATP. This processis done through the addition of oxygen to glucose. The formula belowindicates the process of respiration in a cell.

C6H12O6+6O2 6CO2+6H2O+Energy

Cells utilize light energy from the sun and carbon dioxide to makesugar molecules and oxygen through a process called photosynthesis.Photosynthetic cells include the ones in green plants, cyanobacteriaand phytoplankton. The photosynthetic cells are responsible for themanufacture of complex sugars such as glucose from the simple sugars(Sherwood, 2010). Photosynthesis also includes the use of water tomake the simple sugars. Photosynthesis takes place in two phases, thelight stage which uses energy and the Calvin stage which turns carbondioxide to organic molecules and therefore does not require energy.

Cell reproduction can be described as the process through whichcells duplicate themselves to form another cells that constitutes thesame components as the original cell. The reproduction property oflife is based on this cell reproduction. Cell reproduction has beendivided into two forms on the basis of the type of cells theyproduces (Sherwood, 2010). Mitosis is a form of cell reproductionthat leads to the production of similar cells. Meiosis on the otherhand leads to the production of sex cells.

Mendel’s law is based on the fact that a gene can take multipleforms. It is also this law that states that each trait in an organismis controlled by two alleles. However, the law as also stated thatthe allelic pairs separate during gamete formation. After theseparation, each allele is responsible for the genetic constitutionof the gamete.

Cancer is one of the most disastrous disease in the word today. Ithas been classified amongst diseases such as HIV and Aids due to itsdiverse presence and ability to end life. Cancer exists in over a 100forms. However, one thing common with all the types of cancer is thatit is caused by abnormal cell growth (Bignold, 2009). The damagedcells divide abnormally in huge numbers and form lumps which arecommonly known as tumors. The tumors are responsible for various bodymalfunctions such as interference with the circulatory system,nervous system or even the digestive system.

There are two major mechanisms of gene control that can be used todeal with cancer. The first mechanism involves an extremely complexDNA packaging system that controls the activation of genes for use(Bignold, 2009). It is notable that he cell applies molecularmechanisms to either activate or deactivate the genes based on need.The second mechanism that is used by numerous cancer treatmentcenters is the damaging of Cell DNA of the dividing cancer cells.

References

Starr, C. (2009).&nbsp: The unity and diversity of life.Belmont, CA: Brooks/Cole, Cengage Learning.

Sherwood, L. (2010).&nbspHuman physiology: From cells to systems.Australia: Thomson/Brooks/Cole.

Bignold, L. P. (2009).&nbspCancer: Cell structures, carcinogensand genomic instability. Basel: Birkhäuser.