Running head: BASIC BIOLOGY: CELL FUNCTIONS 1

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Basic Biology: Cell Functions[Author Name(s), First M. Last, Omit Titles and Degrees]

[Institutional Affiliation(s)]

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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

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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)

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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

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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

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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

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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.

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Stages in the Process of PhotosynthesisLight-dependent ReactionsThis is the first stage of the photosynthetic process. These reactions take place in the presence of sunlight, and use light energy from the sun to produce ATP molecules and other molecules known as NADPH. These molecules are used as the energy source to carry out the reactions in the next stage of photosynthesis.Light-independent Reactions (Calvin Cycle)In this stage of photosynthesis, energy-containing sugar molecules are synthesized. The ATP and NADPH produced are used to fuel the reactions in this stage. Here, CO2 molecules are broken down and converted into sugars and other compounds. The Calvin Cycle is repeated twice in order to yield one molecule of glucose.Cellular RespirationCellular respiration takes place in the same way in both plants and animals. Living cells obtain the products of photosynthesis (sugar molecules) and undergo cellular respiration to produce ATP molecules. Some cells respire aerobically, using oxygen, while others undergo anaerobic respiration, without using oxygen. The process involves a set of chemical reactions to convert chemical energy from the glucose molecules into ATP molecules.Chemical reaction in Cellular Respiration

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Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP)

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Stages in the Process of Cellular RespirationGlycolysisCellular respiration begins at this stage in the cytoplasm of the cells, and yields 2 carbon-based molecules called pyruvate, and 2 molecules of ATP. Oxygen plays no part during this stage, so it is called anaerobic respiration.Aerobic RespirationThis process takes place in specialized structures within the cell called mitochondria, and uses the products of glycolysis, the pyruvate molecules, to release energy, along with CO2 and water as the by-products of the reaction. The energy released is stored in the form of ATP molecules. Usually, a total of 38 ATP molecules are produced.

Differences between Photosynthesis and Cellular RespirationPhotosynthesis utilizes sunlight to produce food molecules. Cellular respiration utilizes glucose molecules to obtain energy-storing ATP molecules.Photosynthesis takes place in plant leaves containing the chlorophyll pigment. Cellular respiration takes place in the cytoplasm and mitochondria of the cell.Photosynthesis uses water, sunlight, and carbon dioxide from the atmosphere to create glucose molecules, and releases oxygen as a by-product. Cellular respiration uses glucose molecules and oxygen to produce ATP molecules and carbon dioxide as the by-

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product.Photosynthesis takes place only when there is sunlight. Cellular respiration occurs at all times.Photosynthesis involves conversion of one type of energy into another: light energy into chemical energy. Cellular respiration involves using that chemical energy and breaking it down to release energy.Photosynthesis takes place in two stages of light reactions and dark reactions. Cellular respiration involves aerobic (glycolysis) and anaerobic respiration.Photosynthesis occurs only in plants and some bacteria. Cellular

respiration takes place in all types of living organisms.

ConclusionLife, as we know it, is possible due to a series of events of a chemical nature that occur at the

cellular level. Specific elements need to be present in order for there to be “life.” These elements include

oxygen, carbon, hydrogen, and nitrogen ( ). Those basic blocks of life formation form other important

elements, whose job is to continue to expand our genetic code, which is our blue print. This is the job of

the acids, such as nucleic acid and proteins (. ).

The elements that make life possible combine, reproduce, mix, and perpetuate our existence by

using the environment, and the current condition of the human body, to keep themselves going. This is

why, in all, life depends on environmental variables as much as it depends on internal processes and

genetic pre-disposition.

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References

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Basic Biology: Cell Functions

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