Is Sexual Reproduction Important?

In this blog post I will answer and provide supporting evidence for the question, Is Sex Important? And the short answer is yes. I will delve further into the reasoning and evidence for this answer in four main categories. The benefits of reproducing sexually, the costs of reproducing sexually, the benefits of reproducing asexually and the costs of reproducing sexually. Finally I will summarize all my points and justify why reproducing sexually is the better and safer way to reproduce.

Benefits of reproducing sexually:

Because of the concept of natural selection, genetic variation is crucial to survival. Without genetic variation, there is no evolution, and thus no survival. Genetic variation comes from two main sources mutation and sex.

Sexual Reproduction Benefit 1:

Sexual reproduction is the more sophisticated form of genetic variation. Mutations are random changes to information contained in genes, and is more primitive than sexual reproduction. Mutations only arise from errors made by the cells genetic copying machinery.

Make no mistake, sexual reproduction only produces combinations of genes that already exist, whereas mutation creates altogether new genes, and thus is necessary for generating the raw material of evolution. According to Dr. Tatiana, "Without mutation, evolution would grind to a halt"

Sexual Reproduction Benefit 2: 

Although mutations may be necessary, mutation alone is not enough. When organisms evolve to give up sex, and reproduce asexually instead. (I will explain more about the benefits and harms of asexual reproduction in the following sections, thus is just a comparison between sexual and asexual reproduction)

When an organism reproduces asexually, the differences between a parent are a child, are only due to mutation. According to Dr. Tatiana, "At first, these organisms often flourish. But their glory is fleeting. For reasons that remain mysterious, the loss of sex is almost always followed by a swift extinction."

Although there is one exception to this rule, the need for new combinations of genes that already exist are necessary, and without sexual reproduction, organisms cannot flourish. Most organisms need both sexual reproduction and mutations to properly survive and evolve.

Sexual Reproduction Benefit 3:

The final benefit of sexual reproduction is the ability to reproduce diverse offspring. I previously touched about this at the end of my first point, when I mentioned that in asexual organisms, mutations account for every difference in an organisms genetic makeup.

However, I never applied the importance of this to why sexually reproducing diverse offspring is good and why only mutational differences are bad. I will get to the cons of mutations differences in the "Asexual Reproduction costs," but for now, I will explain why having diverse offspring is helpful.
When having diverse offspring, organisms can ensure that the offspring will always be a combination of the two parents' genes and will never be the exact same, whereas in asexual reproduction, you can never control when mutations should happen.

For example if there is a poison in the environment, and for an organism to survive they need a particular gene. Asexual reproduction might take centuries for that organism to undergo a mutation that gives them that gene, and by the time that might happen, the organism will probably be extinct.
According to Dr. Tatiana, "More often than not, however, some individuals are fortunate and have a gene to resist the poison. Since these individuals are the only ones fo survive and reproduce, the genetic makeup of the population will shift to one where everybody is resistant.

Basically what this means is that sexual reproduction allows organisms to create offspring with genetic variation that might have the gene that resists the poison - If an organism does not have the necessary gene, but their mate does, then the offspring will have a good chance at getting the necessary gene and surviving the poison. Although this is not guaranteed, sexual reproduction allows organisms a better chance to survive the poison.

Sexual Reproduction Benefit 4:In my last point I discussed, how sexual reproduction would give organisms the ability to protect against a poison already spreading through the environment. They did this by mating with other organisms of their species that had a protective gene, to create an offspring that would survive.
This point is similar but it talks about how the genetic variations that sex provides with every reproductions, helps species and organisms survive - you could call it a contingency plan of sorts for the organism to almost always live on.

Genetic variations in every organism, allow each an every organism to have certain genes that protects them against almost any situation. According to Dr. Tatiana, "Monocultures are vulnerable to disease because all the individuals are the same clone," however, sexually reproducing organisms are not as vulnerable, because at least one of the organism should have the necessary genes to protect against anything.

This ensures that organisms that use sexual reproduction, will always survive any attack or poison, and live long, as all of them have different genetic makeups. The only reason that a sexually reproducing organism to go extinct is a drastic change in the habitability of their environment.

Sexual Reproduction Cost 1:

Sexual reproduction is hard to accomplish, and sometimes is a dangerous process. As opposed to asexual reproduction, sex requires two mates. This means that organisms have to seduce each other in order to reproduce sexually. 

According to Dr. Tatiana, "the competition for mates is often exceedingly stiff." Creatures might need to wear gaudy costumes, sing for hours on end, or perform prodigious feats to get a mate. Worse, the competition for mates is often at odds with survival. If you are a bird, flaunting an enormous tail may make you quite the cock among hens, but it also may make you lunch for a cat.

Sexual Reproduction Cost 2:

Another problem in the process of sexual reproduction is the time it takes, not only to find a mate, but to give birth to another organism. Although the time it takes to give birth to the organism may differ among different species, the time it takes to find a mate is never quick nor easy, as explained in my last point.

Asexually reproducing organisms do not need to find a mate, thus the time it takes for them the produce offspring is significantly shorter than the time is takes a sexually reproducing organism to do the same. 

Additionally the chance to make clones, or produce multiple offspring, although possible is very rare in sexually reproducing organisms. In asexually reproducing organisms, there is a much higher chance is producing multiple offspring each time. 

Furthermore, in sexually producing organisms, for example humans, there is usually a time limit between reproducing multiple times, whereas in asexually reproducing organisms, there is usually no time limit. Thus populations of asexual organisms usually grow at a much faster rate, than sexually reproducing organisms.

Asexual Reproduction Benefit 1:

Asexual organisms can reproduce faster and more effectively than sexually reproducing. According to Dr. Tatiana, "Sex may be fun, but cloning is much more efficient. All else being equal, an asexual female who appears in a population should have twice as many offspring as her sexual counterpart."

The reasoning for this is because in a sexual population, for example the human population, each female must have two children for the population to stay the same size. To cause the population to grow, each female in the population needs to average more than 2 children. If females average less than 2 children in a sexually reproducing population, the population will automatically shrink.

However, if an asexual female reproduces, it ensures that the population size will be maintained. If the organism reproduces more than once, then the population will automatically grow.

Asexual Reproduction Benefit 2:

Asexual reproduction is easy and does not take much time, while still allowing asexually reproducing species to produce multiple mates.

In asexual reproduction there is not necessity to find a mate, significantly lowering the time and difficulty it takes to reproduce. Additionally the reproduction itself does not take as much time as sexual reproduction. 

Another benefit that comes with the time factor is the quantity. Because of the shortened time and small amount of difficulty, asexually reproducing species can reproduce many more offspring in a small amount of time that sexually reproducing species can produce in a lifetime.

Asexual Reproduction EXAMPLE - Benefit 3:

One perfect example of an asexually reproducing species that has lived long for 85 million years is the philodina. It has not needed a single mate, and has produced many offspring.

Asexual Reproduction Cost 1:

Asexually reproducing organisms have no genetic variation. All the offspring of asexually reproducing organisms are genetically identical, aside from mutations that take place.  This means that every asexually reproducing organism is resistant to change.

This is one of the primary reasons that asexually reproducing species, according to Dr. Tatiana, "swiftly go extinct." If there is a poison, if one asexual organism in a species does not have a gene to fight the poison or virus, then none of the species will survive.

However, in sexually reproducing organisms, like humans, certain organisms have different genes that give them the ability to fight off viruses and diseases (as mentioned in the first benefit of sexual reproduction), even if one of the organisms die because of the virus.

These are the reasons that most sexually reproducing organisms thrive in our society, while asexual reproducing species usually go extinct swift because of pathogens that they are not resistant to.

Questions and What you want to learn more about:

I really want to learn more about the how pathogens affect sexually reproducing species versus asexually reproducing species.

I did not really understand why and how mutations happen, and what genes they specifically alter.

Unit 3 Reflection

In this unit, we learned all about cells - everything from their structure to their function(s) to their organelles. Some of the major sub topics covered in this unit were membranes, osmosis and diffusion, macromolecules found in the cell, the organelles in a cell, the history of cells, photosynthesis, and cellular respiration. In this unit, I really enjoyed doing all of the labs, especially the microscopic organism lab. The ability to magnify the organism, really solidified my learning, and was able to give me a deeper understanding.

Strengths and Weaknesses:

I really found myself to be good at understanding pictures under the microscope, and identifying key parts of the cells. However, I could never really get good pictures under the microscope, as my hands could never stay still. :(

Another strength I found in myself was my ability to interpret data. For the egg diffusion and egg macromolecule lab, this skill helped me understand why certain macromolecules were present in parts of the egg, and why egg grow and shrink in different types of liquids.

I think I am a better student than before this unit, especially because of the labs we did. The labs allowed me to test certain theories that I was not sure were true. They also provided me with a way to look closer and the cells. I also learned a life lesson from these experiences. There is always a reason. In this unit I refused to accept the answer, "That is just the way it is" and set out find why it is that reason. And I learned that there is always a reasonable explanation.

I want to learn more about the organelles of a cell and their specific functions. I want to look at the organelles closer in an electron microscope and see where the magic happens of photosynthesis. I always wonder about what we will find, when we keep looking closer at the cell.

Microscope Organism Lab Analysis

The above diagram is of an amoeba cell. We were able to identify the nucleus, cell membrane, cytoplasm and pseudopods. One of the unique characteristics about this cell is that is has pseudopods to walk, and another is that they have different colors within the cell. One observation about the cell is that is has a cytoskeleton. The amoeba is a eukaryotic cell that is heterotrophic using their pseudopods to eat other cells.

The diagram above is of a euglena cell. We were able to identify chloroplasts, the nucleus, and the cytoplasm. However we could not identify the flagellum. One unique characteristic about the cell is that it has flagellum. Although it is very hard to see in the image above, flagellum are very rare in cells, but do exist in euglena. These are eukaryotic cells, but can be both autotrophic and heterotrophic.

The diagram above is of a bacteria cell. The coccus, bacilis, and spirilum are identified on the cell. The size of this cell compared to other cells, is extremely small, and an observation about the cell is that the bacteria are not in any particular formation - they are all just floating around. Bacteria are prokaryotic, heterotrophic cells. (400x)

The diagram above is of a spirogyra cell. On the cell the cell, the cell wall, cytoplasm and chloroplasts are identified. The cytoplasmic strands that hold the nucleus in place are one of the unique characteristics about the cell. One observation about the cell above, is that it has spiral chloroplasts, something that most plant cell's don't have. It is a eukaryotic, autotrphic cell. (400x)

The diagram above is an example of a plant ligustrum cell. It is an autotrophic eukaryotic cell. A main unique characteristic of the cell above is the epidermis cells surrounding it.  You can clearly see the chloroplasts, the blueish green places, where photosynthesis occurs. The veins of the cells are also very clearly visible. One observation about the image above is that all the cells are very compact and the cell walls are extremely thick, compared to other cells. (400x)

The diagram above consists of animal muscle cells, known as muscle fibers. We were able to label the nuclei (purple dots), the muscle fibers (long strands across cell), and straitons (the bands of fibers). One of the characteristics of the cell shown above that is unique is the fact that they are multinucleate cells. They have many nuclei fused together in one cell. An observation I made about the cell is that  the nucleus is not always surrounded in a certain way, it differs for each muscle cell. The animal muscle cell is a heterotrophic, eukaryotic cell. (Note: The microscope that took this picture was at x400 zoom, and after picture was taken, the image was zoomed in)

The diagram above is of cyanobacteria, also referred to as blue green algae. It is a bacteria, which means it is a prokaryotic cell and it is autrotrophic. One unique characteristic about cyanobacteria is that they were the first types of cells to perform photosynthesis. One unique characteristc seen in the slide is the formation of each cell of cynaobacteria. They live in clusters as opposed to a compact formation. One other observation is that the cells are never in a particular or similar shape, rather different types of round shapes. (400x)

Cell Characteristics

The autotrophic cells were usually green. They also all had chloroplasts as most of the autotrophic cells we observed were plants - and plants need chloroplasts to perform photosynthesis. Most of the autotrophic cells, although it may not have been visible, also had mitochondria, so they would perform cellular respiration.

The heterotrophic cells were mostly eukaryotic except for the bacteria, and most of them utilized some of their special characteristics to help them eat other cells - like the amoeba using its pseudopods.

All the eukaryotic cells had nuclei and all the prokaryotic cells lacked nuclei. Most of the prokaryotic cells were bacteria.

Egg Diffusion Lab Analysis

In this lab we tested the effect two solutions, one hypotonic, and one hypertonic would have on egg mass and circumference.

One of the eggs was placed in sugar water, while the other was placed in deionized water. The sugar water was a hypertonic solution, thus the egg shrunk in both mass and circumference. It had an average of -42.17% change in mass, and a -19.67% change in circumference, as it was going from high to low concentration - diffusion. The solute concentration was greater outside and the solvent concentration was greater inside. The cell tried to move into equilibrium, by using passive diffusion through the membrane, forcing solvent outside the cell, thus, causing the egg to shrink.

The other egg was placed in deionized water, a hypotonic solution, thus the egg grew. The movement of solvent inside the cell, caused the cell to grow by an average factor of 1.18% for mass and 1.94% for circumference.

Because the cell has to stay in equilibrium to maintain the balance of solute and solvent concentration, both the cell's internal and external environments change. This changes occur either through facilitated or passive diffusion through the cell membrane.

This lab demonstrates diffusion and hyoptonic and hypertonic solutions. It shows how a cell will always want to get into equilibrium despite the fact that it must change size to do so.

Fresh vegetables are sprinkled with water, so they can grow larger, while roads are sometimes slated to turn the roadside ice into water.

I would want to test what type of hypertonic and hyoptonic solutions cause the solute and solvent concentrations to change the quickest.

Egg Cell Macromolecule Lab Analysis

Clockwise starting from top left: Egg Membrane, Egg White, Egg Yolk, Pure Water

Egg Macromolecule Lab Analysis

In this lab we asked the question: Can macromolecules be identifies in an egg cell? And we found an overarching answer that macromolecules can be identified in all parts of the egg cell, whether it is the egg yolk, the egg membrane or the egg white.

Egg Membrane

Claim: The Egg Membrane tested positive for the macromolecule of lipid. We tested the presence of lipids in the membrane by mixing the egg membrane sample (shown in the top left of the picture above) with Sudan III, a solution that causes the sample to turn from red to orange if lipids are present.

The color change for the egg membrane in Sudan III

Evidence: When the Sudan III was mixed with the egg membrane, the sample did turn to a shade of dark orange. On a rating scale of 0 to 10, (0 = color of the negative control, 10 = very dark shade of orange), we ranked the color change to be 8.5 - The picture to the right shows the egg membrane mixed with Sudan III. This data clearly indicates that there is a strong presence of lipids in the egg membrane.

Reasoning: The bilayer of the cell membrane is made up of phospholipids - which are lipids what have a phosphate group in its molecule - nevertheless still lipids that are a major part of all membranes. Other types of lipids that are found in the egg membrane include cholesterol and glycolipids. Cholesterol maintains membrane structural integrity and fluidity, making it another essential part of the membrane. Glycolipids help maintain the stability of the membrane and act as a recognition site for certain chemicals to pass in and out of the cell membrane. All in all, lipids are a major and essential part to the function and structure of cell membrane, thus are present in the cell membrane. 

Egg White

Claim: The Egg White tested positive for the macromolecule of protein. We tested the presence of proteins in the egg white by mixing the egg white solution (shown in the top right of the picture at the very top) with sodium hydroxide copper sulfate, a solution which would turn any sample from blue to purple if the sample had proteins present. 

Proteins present in Egg White

Evidence: When sodium hydroxide copper sulfate was mixed with the egg white (shown in image to the right), the sample turned to a shade of dark purple. On the aforementioned rating scale, we rated the color change as a 6. The color change rating, compounded with the image shown to the right, clearly shows that there is a presence of proteins in the egg white.

Reasoning: The primary function of the egg white is to protect the yolk, also known as the nucleus of the egg cell. Proteins are found anywhere there is a membrane, because they (1) transport molecules and ions across the membrane as transport proteins, and (2) are attached to the lipid bilayer to help protect the cell as "integral membrane proteins." Some of the types of proteins present in the egg white are albumins, mucoproteins and globulins. The presence of proteins in egg whites does not just include transport and integral proteins, but is compounded by the fact that egg whites have 50 percent of the total protein in the egg. Thus, because the egg white's purpose is to protect the yolk, and proteins are found anywhere in the cell that serves as protection, proteins are present in the egg white solution.

Egg Yolk

Claim: The egg yolk tested positive for the macromolecule of lipids. We tested the presence of lipids in the egg yolk by mixing the egg yolk solution (shown in the bottom right in the very top image), with Sudan III, a solution which would turn any sample from red to orange if the sample had lipids present.

Evidence: When Sudan III was mixed with the egg white, the sample did turn to a shade of dark orange. On a rating scale of 0 to 10, (0 = color of the negative control, 10 = very dark shade of orange), we ranked the color change to be 4 - The picture to the right shows the egg yolk mixed with Sudan III. This data indicates that there is a presence of lipids in the egg membrane.

Reasoning: Egg yolk has both cholesterol and phospholipid contents. Cholesterol is a type of lipid that is present in the egg yolk, which helps protect the egg yolk, which is the nucleus of the egg cell. Phosvitins are also a type of protein present in the egg yolk, and they are important in getting calcium and iron to the nucleus. LIPIDS are found wherever there are membranes, as they are essential for any protection inside the cell. As the yolk is the nucleus, it contains a nuclear membrane, and thus lipids will be present in the nucleus.

Possible Errors

While our hypotheses were supported by our data, there may have been some possible errors during the steps of the experiment. One of the possible errors is the amount of solution placed into the egg yolk, egg membrane or egg white. If there was too much solution, whether it was Sudan III, sodium hydroxide copper sulfate, iodine, or benedicts, the effect of the solution may have been exaggerated. If there was too little solution, the true effect and potential of the solution may not have been shown. Although we tried to set a specific number of solution drops to limit the possible error percentage, no one can account for how much one drop is, how many drops may have accidentally be put in.

Another possible error could have been the mixing of the solution and the sample. One person may have mixed the solution and sample extremely well, clearly showing the color difference and properly telling us what macromolecules were present in each of the samples, however others may have recorded their data without properly mixing their solution and sample. If this did happen, the effect of the solutions on the samples would not have been shown, and would give us incorrect data to analyze. However the possibility of this is minimum. Although some people may have mixed the solution and sample more than others (ex. more time spinning the tubes), the procedure told us to mix it well, and the couple extra mixes would not provide too much of a data difference.

Two recommendations that I would give when doing this experiment in the future is to put the exact amount of solution (that should be poured) into a separate petri dish, that way groups can simply pix it up, and dump all the solution into the sample. This would prevent any errors of the quantity of drops from taking place. The second recommendation that I would give is to give the exact number of seconds a student should spend mixing, or the number of times a student should spend mixing, thus eliminating any possibility of excess or insufficient mixing.

Practical Applications

This lab was done to demonstrate the macromolecules that are present in all parts of the egg cell. From this lab I learned that every part of the egg cell, whether it is the egg yolk, egg membrane, or egg white, has at least one, if not multiple, macromolecules present. This helps the understand the concepts of macromolecules - especially the structure and function that each macromolecule serves in each part of the egg cell. This also helps me better understand the importance of macromolecules, as well as what each part of the cell does. With better knowledge of macromolecule function, I can quickly relate to and understand different functions of different cells. Based on my experience from this lab, I can eat much better. I understand that the egg yolk is mainly a source of cholesterol and saturated fats, both of which are not extremely good for your body, and that egg whites are the egg's main source of protein. This has allowed be to shift my morning meals from being full egg omelets, to solely egg white omelets, something that will hopefully help me put on more muscle, and still stay very healthy.