Every living thing is made up of microscopic building-blocks called cells and may contain one cell or many cells. Unicellular organisms are called prokaryotes, and multi-cellular organisms are called eukaryotes. Cells of unicellular or multi-cellular organisms perform basic life functions.
How Cells Carry Out Functions Required for Life
Coordinated life processes explain how cells carry out functions required for life and survival. An organism’s metabolism is all the life processes of an organism that enable it to survive. The following are eight life processes of living organisms.
Organisms require energy intake in order to survive. Every living thing consumes energy. Plant cells derive energy by converting light from the sun into sugars through the process known as photosynthesis. Animal cells derive energy from the nutrients that the animal ate.
Cell organelles and life functions are specialized for each organism's needs. Photosynthesis occurs in a cellular organelle termed the chloroplast, which contains a pigment called chlorophyll.
Using the metabolic energy derived from nutrients, cells are able to move independently. Prokaryotes move around their environments using one of two specialized appendages — cilia or flagella. In addition to outward movement, cells are continuously actively moving various molecules around the internal space of the cell.
Growth is the life process by which organisms increase in the number of cells or grow in size. In the human body, for example, cells of the skin divide and create new cells to replace the dead ones that are shed. Eukaryotes grow in number of cells through a process called mitosis.
Organisms are constantly making new offspring from parents. Every single organism is an offspring of another organism. Reproduction can occur in two ways — asexual and sexual reproduction. Asexual reproduction involves one parent whereas sexual reproduction involves two parents.
Prokaryotic cells divide asexually through a process called binary fission in order to create two cells that are identical to the progenitor or “parent” cell. Animals and plants reproduce sexually, so offspring have a mix of DNA from both parents.
All organisms have life processes that enable the repair of tissues and DNA. Mutations in the genetic code of an organism can be deadly. For example, cancer can arise from mutations. Cells have specialized proteins that “scan” the DNA to look for random mutations and repair them.
Sensitivity refers to the life process whereby a cell gains knowledge of its surrounding environment. Through chemical and electrical signals, cells pick up information about their environment depending on the needs of the organism. For example, cells of the skin are specialized for sensing minor changes in pressure, giving us a sense of touch.
Environmental factors detectable by cells can include heat, pressure, pH, and the presence or absence of nutrients. The cell uses sensory information from the environment to determine activities and regulate itself. By sensing the location of chemicals in the environment, single-celled organisms can move towards nutrients and away from toxic substances.
Living things make potentially harmful waste products from normal metabolic reactions. Excretion is the process of removing waste. Whenever you breathe out carbon dioxide, you are excreting a metabolic waste product. Cells will contain harmful chemicals in sacs called vacuoles. Vacuoles release contents to the exterior environment through a process called exocytosis.
Respiration is a life process where cells gain energy by breaking down nutrient rich macromolecules in order to create adenosine triphosphate (ATP). ATP stores energy for the cell to use in chemical bonds. Energy is released when these chemical bonds are broken down. There are two types of respiration aerobic, which uses oxygen, and anaerobic, which does not involve oxygen.
- amoeba and plankton through microscope image by Allyson Ricketts from Fotolia.com