BASIC BIOLOGY: CELL FUNCTIONS9
Basic Biology: Cell Functions
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Basic Biology: Cell Functions
Cells and the process of life
Life is a series of physiological and chemical processes that maintain a body alive. All of
those complexities could not take place without the existence of the basic unit of all life sources:
the cell. As building blocks of life, cells make up everything we know to be alive, whether it is
human, animal, micro organic, or plant-based. The processes that take place within the human
cell are responsible for mainly every other life process to be possible.
Cells are approximately one micrometer in size. They are a circular “sack” of organelles
(small organs) that are protected by a plasma membrane that is semi-permeable. Inside, the
organelles float in a viscous clear liquid called cytoplasm. These organelles are to cells what
human organs are to people. They all have a function. For example, the vacuoles hold the cell’s
food, water and waste until it is time to release them. The endoplasmic reticulum (ER) produces
ribosome proteins and important lipids for proper cell functioning. The Golgi apparatus moves
the proteins around. Meanwhile, the mitochondria are the energy suppliers of the cell; they turn
basic nutrients into energy. All cells have a nucleus, or center of operation, which holds
deoxyribonucleic acid, or DNA, the blueprint of life. Cells to clone one another and multiply
through the process of mitosis, or cell division. Yet, there is more to life than just cellular
processes. The complexity is larger than that.
Properties of life
There are processes that are inherent to living beings. These are called the properties of life. These are activities that take place among the living in a natural way. It is part of the survival mechanism of living things, and it helps to expand their lifespans. The processes are: order, stimuli, reproduction, development, regulation, homeostasis, and processing energy (Simon, Dickey, Hogan, Reece, 2015).
Basically, order refers to how cells organize themselves to form structures. In the case of humans, the cell order begins with the atom, or the basic unit. Atoms make molecules. Molecules make up the organelles of the cells. This happens in one-celled living things. In multiple-cell living things, like us, the cells form tissues, which form organs such as our stomachs, and lungs, and then these organs work together in systems (Simon, Dickey, Hogan, Reece, 2015).
Reproduction and development refer, respectively, to duplicating our deoxyribonucleic acid (DNA) and to the posterior development of the species. In reproduction, multicellular beings would pass genes containing DNA its offspring (Simon, Dickey, Hogan, Reece, 2015). Development occurs in all living things. In the offspring, it entails growing physically. In beings that are already grown, development entails maturing and aging. Regulation and homeostasis are processes that are related. When it comes to “regulating activity,” all living beings must regulate activity to operate and live optimally from the inside out.
At the cellular level, there are also mechanisms that regular the cell’s growth within themselves. This is called mitosis, or cell division and reproduction. The steps of this are: a) prophase, when the centrioles separate and the nuclear membrane breaks down, b) metaphase or when the chromosomes line up in the middle of the cell, c) anaphase, where these chromatids separate into chromosomes and move apart and, d) telophase, when the chromosomes shift to opposite ends of the cell and new nuclei membranes form (Simon, Dickey, Hogan, Reece, 2015). This is not the only way that a cell regulates itself. For example, when a cell starts growing large during a process, its surface to volume ration changes by making the cells smaller (Simon, Dickey, Hogan, Reece, 2015). Also cells automatically divide in order not to get too big and die. This is also because if a cell gets too large, it will have problems with the movement of nutrient across the cell’s membrane. In a way, cells do a lot of work to preserve themselves.
Homeostasis is related to regulation because the right conditions must be present for them to occur. Homeostasis, at the cellular level, entails that things such as temperature, chemicals, and pH need to be in optimal amounts for the processes to occur. The way that cells divide, transport nutrients, and flow is an example of how organs do the same thing in order to keep the body balanced. The organs work together to keep this balance the same way that the cell undergoes process to regulate its own functions (Simon, Dickey, Hogan, Reece, 2015).
Energy processing is a basic process that is used by all living beings. Metabolic activities could not be possible without energy. In plants, for example, the energy is produced by absorbing it from the sun and converting such energy into food through photosynthesis. In humans and animals, food is the primary source of energy. Regardless, whether plant or animal, energy is the key source of life that allows for all the life processes happen. Without energy, there could not be life. (Simon, Dickey, Hogan, Reece, 2015)
Photosynthesis and cellular respiration
Photosynthesis and cellular respiration are two important processes for living organisms to tap on energy sources found in nature. These processes aim for the goal of obtaining energy. During photosynthesis, plants use the energy they absorb from the sun through their leaves. The energy goes to structures in the leaf called chloroplasts, which hold on chlorophyll. This latter is the substance that makes plants green. The combination of energy, carbon dioxide and water will produce oxygen and glucose in a process called the “Calvin Cycle.” The glucose will become the plant’s key food source, which will allow for more metabolic processes to continue to happen.
Cellular respiration happens in animals, particularly in the cell’s mitochondria and cytoplasm parts of the cell. While plants get their food energy from the sun, cellular respiration consists on breaking down the nutrients from food to get energy. This energy source is also stored as ATP, or adenosine triphosphate molecules. For this to happen, two things need to happen. Glycolysis, or anaerobic respiration is when cells use glucose to yield 2 molecules of pyruvate and 2 of ATP without using any oxygen. The second process, aerobic respiration, occurs when the pyruvate molecules that were produced in anaerobic respiration are used to release carbon dioxide, water, and energy. Then the energy is stored as ATP molecules and the body uses it as it moves and engages in activities. (Simon, Dickey, Hogan, Reece, 2015)
Genetics gone wrong: Cancer and Mendel
More than 100 years ago, Gregory Mendel, an Augustinian monk, discovered what is now known as phenotype and genotype. These are the pillars of his genetic theory. According to it, variance among living beings is based on inherited traits that come from the living things that helped to bring us to life. We are, basically, varied copies of our ancestors. Phenotypic characteristics are all the traits we possess, from physical to behavioral, that we inherited. In theory, we are meant to look and behave like our ancestry. Genotypic traits are the internal genes we carry, such those that increase our propensity to suffer from specific diseases. One of these diseases is cancer. (Simon, Dickey, Hogan, Reece, 2015)
The epidemiology of cancer suggests that some malignancies tend to be collected from generation to generation. As such, one family may have a higher tendency to develop a cancerous condition than another simply because the gene is present in the family’s genealogy.
What is known as “cancer” is basically a growth of cell that cannot be controlled by the natural processes that cells go through. Cancer cells grow unchecked by these processes. When they grow, they can mutate because of fast cell division rates. The bad control of a cancer cell can make it develop into a tumor, and attack surrounding cell tissues, even bodily systems. This means that a cancer tumor that begins in one system, for example, the bones, could travel to the digestive system, the brain, or any other working organ in the body. This “traveling” of cells may cause for new tumors to develop.
In conclusion, cells are the basic elements of life. Inside themselves, cells also undergo a life of their very own. Like the bodies they form, they multiply, breathe, grow, excrete, and die. They also experience malformations in what we know as “cancer.” Gregory Mendel, a monk, was perhaps the first investigator that noted the variances in inheritance that are caused by what cells carry within. What this means is that cells carry within them genetic codes that produce the phenotypical (physical) and genotypic (genetic) characteristics that makes us all unique from others that do not come from our very own genetic pool. In other words, we are the product of variances in our ancestry dating back thousands of years. We are what our ancestors were, or at least a variance of it. Cells exist in all living things, from human, to plant, to animal. Each genetic code is different and cannot be crossed among one another. This means that humans and plants cannot be genetically crossed with success, and neither can humans be crossed with animals. In all, cells are replicas that carry important genetic codes that are, essentially, the code of our lives and the lives of all things.
References
Simon,D. Dickey,R., Hogan,C., Reece, V. (2015) Campbell Essential Biology
New Jersey: Pearson.