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All living organisms are composed of cells. A cell is a small, membrane-bound compartment that contains all the chemicals and molecules that help support an organisms life. An understanding of the structure of cells is one of the first steps in comprehending the complex cellular interactions that direct and produce life. Cells can be thought of as building blocks of organisms.
Some organisms are composed of a single cell. Others, like ourselves, are composed of millions of cells that work together to perform the more complex functions that make us different from bacteria. It is difficult to imagine that humans are descendants of a single cell, but this is a common belief in the scientific world. Before we can understand how multiple cells can work together to create complex biological functions, it is necessary to understand what biological functions single cells are capable of performing on their own to sustain life. There are different types of cells with individuated structures.
Single-celled organisms have different cell structure than multi-celled organisms and plant cells have different structures from animal cells. These differences reflect differences in the functions that each of these classes of cells is required to perform. Metabolism is the process by which living organisms acquire energy from external sources and utilize it internally in order to carry out necessary cellular activities. Respiration is a means of acquiring energy through biological degradation of food molecules. Cellular reproduction is a process by which cells duplicate their contents and then divide to yield two cells with similar, if not duplicate, contents.
Understanding this process is helpful in understanding the basis for human reproduction as well as the basis for the generation of life in other classes of organisms. Cell reproduction does not always result in new independent cells. It is also essential to growth and development as well as in the day-to-day maintenance of many human cells. These processes are responsible for creating two different types of cells. Mitosis is a process that creates a nearly exact copy of the original cell.
Somatic cells, which include nearly all human cells, are created by this process. Meiosis is a different form of reproduction that leads to the production of germ cells, or sex cells. All cells fall into one of these two categories. Some organisms, such as bacteria and single-celled organisms, use only mitosis for cell reproduction. The difference between mitosis and meiosis can also be thought of as the difference between sexual and asexual reproduction. Humans obviously reproduce sexually, but this is not true for all organisms.
Many lower-order cells create entirely new organisms with each round of mitosis: asexual reproduction. In humans and other organisms that reproduce sexually, meiosis is needed to take into account the genetic contribution of the two parent organisms. DNA is the nucleic acid that is responsible for programming many or our traits. As the material that composes our genes, DNA has become one of the most fundamental molecules in molecular biology. As DNA and RNA are the major molecules of molecular biology, understanding their structure is critical to understanding the mechanisms of gene replication and protein synthesis. The structural elements of each of these molecules play key roles in their performance in various processes.
Life began on a small scale. The first organisms were single cells. Sometimes small groups of cells formed. Eventually, these microorganisms evolved into complex multicellular organisms. The fact that microorganisms still exist today in many forms is a testament to the quality of this original life form. Microorganisms have adapted to inhabit almost every corner of the world.
They live in the oceans and lakes, where they provide a valuable food source for larger organisms. They live on land where they influence the decay of dead organic material, recycling valuable nutrients. Many even live within other, larger organisms that they may help or hinder. Humans have several reasons to be interested in the study of microorganisms. Many microorganisms cause disease in humans.
Bacteria and fungi can be parasites of humans, causing anything from food poisoning to athletes foot to malaria. All viruses are disease-causing. Viruses are responsible for deadly diseases such as AIDS and polio, as well as milder forms like the common cold. Some viruses have even been implicated in the development of cancer. We also have several positive relationships with microorganisms. Some soil bacteria fix atmospheric nitrogen, making it available to the plants we eat.
Certain fungi grow symbiotically with plant roots, increasing their ability to obtain food and moisture from the soil. Others fungi are themselves quite tasty. Bacteria and protists that live in our intestines help us gain nutrition from food. Microorganisms have also gained importance as tools in the scientific world. Since most have simple life cycles and can reproduce rapidly, they make ideal model organisms. Topics like genetics that are difficult to study in larger organisms because of the time and expense involved in raising them can easily be studied in microorganisms living in petri dishes by the billions.
Overall, microorganisms are some of the most important living creatures. Their role as producers and recyclers makes them vital in most ecosystems. A greater understanding of these tiny creatures is vital for the study and preservation of our natural environment.
Free research essays on topics related to: living organisms, molecular biology, human cells, single celled, asexual reproduction
Research essay sample on Asexual Reproduction Molecular Biology
