Why All Organisms Are Considered To Be Alive

All organisms that are considered to be alive must possess certain key characteristics or functions. These include: order, response to the environment, reproduction, growth and development, regulation, energy processing and evolution. Since we recognize life by what living things do, these seven characteristics serve to define life. Organisms consist of one or more cells and while they may be very complex they are highly organized and coordinated. Inside each cell, atoms make up molecules. Molecules in turn make up cell organelles and other cellular inclusions. Similar cells form tissues that then collaborate to create organs. Additionally, each cell can only perform the job associated with its specific function such as heart cells, brain
In order to understand the function of DNA, we need to first structure of DNA. DNA molecules are polymers: Polymers are large molecules that are built up by repeatedly linking together smaller molecules; called monomers. They area also monomers are called nucleotides. A molecule of DNA is a bunch of nucleotide monomers, joined one after another into very long chain. Genetic information is carried in the linear sequence of nucleotides in DNA. Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs. These chains are composed of four types of nucleotide subunit and are joined together by covalent bonds between the sugar of one nucleotide and the phosphate of the next. The main role of DNA in the cell is the long-term storage of information. It stores information for making and coding other large molecule call protein and are vital in inheritance and the genetic blueprint of
When a cell becomes abnormal and begins to grow out of control cancer develops. When mutation changes a cell's DNA sequence cancer may begin. Damage to DNA can be cause by factors in our environment; these factors such as smoke, radiation from the sun and other toxins. Most often DNA repairs itself. However, when DNA repair is unsuccessful cancer can occur. Also perhaps suppressing is that cancer can be caused by malfunctions and mutations in the genes that govern the cell repair itself. There are tumour suppressor genes, which work to fix DNA error. However, if damaged, tumour suppressor genes can lead to cancer. The second are oncogenes which are mutated form of normal genes known as proto-oncogenes those oncogenes carry DNA sequences known to lead to cancer. Viruses seem able to cause cancer in three ways The area of DNA and genes is a crucial one with regards to cancer... Presence of the viral DNA may disrupt normal host DNA functions. Viral proteins needed for virus replication may also affect normal host gene regulation. Since most cancer-causing viruses are