How do different UV light intensities affect the growth rate of yeast (Saccharomyces cerevisiae)?

When we think of sunlight, we quickly link it to positive experiences in our lives, like a beautiful spring day that made us feel better or our most recent summer vacations spent at the beach, for example. UV rays are essential for photosynthesis in autotrophs like plants and humans to produce vitamin D, which is crucial for calcium absorption in our bodies.

However, it is crucial to remember that sunshine releases potent electromagnetic radiation, which could be harmful to our health if we do not take precautions. The sun emits infrared, visible, and ultraviolet photons when the electromagnetic spectrum is considered in its entirety (UV). Although it may appear that clouds are blocking some of these wavelengths, the UV rays of sunlight are not being prevented. Depending on the wavelength 2emitted, UV radiation can be divided into three categories: UVA, UVB, and UVC. Thus, these differ from one another, dependent on the ozone layer's absorption. The strongest UVA 3 rays travel through the atmosphere and into the Earth because the ozone layer does not absorb them. Intense ultraviolet (UV) light from the sun can harm skin cells and perhaps lead to skin cancer. UV light is a mutagen that can lead to uncontrolled cell division and tumour development. This tumour may or may not turn out to be cancerous. If it is cancerous, the phases could progress to cancer and, if left untreated, metastasis, the development of secondary tumours due to the lymphatic spreading brought on by the initial malignancy. I used Saccharomyces cerevisiae as my model organism to investigate the impact of sunshine on live cells.

Yeast (S. cerevisiae), a eukaryotic single-celled organism, is grown in colonies. The glycolysis process in yeast results in the anaerobic, oxygen-free synthesis of two net ATP and two NADH from converting one glucose molecule to two pyruvate molecules. Yeast cells are a part of the kingdom of fungi. Though they share similarities with humans regarding the cell cycle, DNA replication, metabolism, and cell division, they are frequently used as models for cell biology. Research on yeast (S. cerevisiae), the official term for yeast, has enabled the complete discovery of human biology because of these seven similarities to human cellular structure. By exposing yeast during fermentation, an anaerobic process, to various distances from a UV source, the effect of UV light on the proliferation of yeast cells will be investigated. This will help us understand the harmful electromagnetic radiation might do to human skin.

As was previously noted, UV light can impact cells, impairing their ability to carry out essential tasks. Cells from Saccharomyces cerevisiae are classified as fungi. However, because of the similarities between their cell cycle, DNA replication, metabolism, and cell division and those of humans, they serve as a standard model for cell biology. This fermentation occurs when growing yeast cultures involves anaerobic respiration yielding energy from ATP and more substances such as FADH_​2, NADH, and CO​₂ ​without oxygen.

By measuring the circumference of the balloons of the samples exposed to UV light more closely, we could predict that the experiment's results would show a low rate of carbon dioxide production. This is because radiation will stop colonies closest to it from fermenting and growing, resulting in less carbon dioxide, which will be visible in a smaller circumference measurement. This means yeast colonies closer to UV light grow slower than yeast colonies farther away from the light. As previously indicated, the energy emitted by UV rays varies based on their wavelength, which can impact yeast (S. cerevisiae) growth if the temperature rises. In order to prevent modifications to the fermentation process that can have a detrimental impact on the results, the UV lamp will be an LED.

• Dry active baker’s yeast ( ​S. cerevisiae), and chemical yeast will not work.
• 3.5 W LED UV lamp, due to the number of trials, preferably many units would be useful. However, this experiment was conducted with 2 units.
• 5 flasks with a capacity of 250 ml
• 112.5 grams of sugar
• Bunsen burner
• Goggles
• Gloves
• 240 ml of distilled water
• Beaker
• 25 balloons
• Measuring tape
• Mass Balance
• Elastic bands (25 units)

The experiment is conducted in the lab at the school. We will use gloves and goggles and clean our hands before and after the experiment. To protect our skin from bacteria and the substances used to sanitize our products, gloves must be worn. These safety precautions were made to protect us from the lab-grown yeast (S. cerevisiae) and shield the yeast from outside influences that might interfere with data collecting. Due to the bleaching of the yeast (S. cerevisiae) and the disinfection of all surfaces, disposal is not detrimental to the environment. When handling alcohol and bleach, as well as before and after the entire experimentation process. In addition, no eating or drinking occurs while the microbe is starting to ferment. In order to prevent confusion and any potential laboratory accidents, all of the cultures were labelled.

• The surface where the experiment will be conducted needs to be cleaned before starting to prevent other bacteria that could obstruct the growth of the yeast (S. cerevisiae) culture. Avoiding moist and warm regions will also ensure the best circumstances for yeast growth. It should be sufficient to wipe the surface with alcohol, keep the space clear, and only leave the materials that will be utilized.
• Before changing the year, wash your hands for safety's sake.
• To eliminate any contamination focus, the glass containers and flasks will be steam-sterilized for 10 minutes. A different method to effectively disinfect these materials would be to immerse the containers in boiling water for 30 minutes.
• A portable flame torch should be used to sterilize the objects to ensure proper disinfection and prevent germs from interfering with yeast fermentation (S. cerevisiae).
• Since the ideal ph for yeast fermentation is neutral, it is preferable to use distilled water to prevent chemical ph from influencing the experiment's outcomes.
• Pour 4.5 grams of granulated sugar into the 5 flasks.
• Add 5.5 grams of active yeast (​S. cerevisiae​) into the 5 flasks
• Pour 200 ml of distilled warm water between 25 to 35 degrees Celsius.
• Add UV lamps and place them at various distances from the flasks (9 cm, 19cm, 24cm, and 30 cm). There will be five distinct measurements made from the containers. One of these will not receive UV light exposure as a control. Label the distances on the flasks.
• Each flask's mouth is covered with stretch balloons. This will serve as a means of measuring the balloons' circumference and tracking the CO₂ trapped inside of them. This method will be used to gauge yeast (S. cerevisiae) growth. To prevent gas from escaping, secure it with elastic bands.
• Leave yeast (​S. cerevisiae​) exposed to UV lamps for 60 seconds.
• A flexible tape measure will be used every ten minutes to measure the balloons' circumference, and the findings will be recorded.
• Discard yeast (S. cerevisiae) colonies after the experiment is finished by cleaning them with bleach and sanitizing the workspace with alcohol before leaving the lab.
• Repeat the experiment until there are five trials, at which point data is displayed in the results section, filled in in tables, and a graph is plotted.

As the results demonstrate, there is a tendency for the balloon circumference to decrease with increasing UV light proximity. For instance, the balloon's lowest circumference measurement was 26 cm during flask 2 to's third experiment, which was 9 cm from the UV light. In contrast, the control flask, which received no UV radiation at all, had the most prominent figure for balloon circumference at 32.5 cm. Additionally, all the experimental data show that UV radiation hurts yeast (S. cerevisiae) fermentation since the balloons closest to the UV light have smaller circumference measurements. The findings largely support the idea.

Despite some variations being visible, flask 3 in the first trial, which was 19 cm from the UV light, grew more, measuring 26.8 cm of balloon circumference, compared to flask 2, which was only 9 cm away, measuring 26.2 cm, and flasks 4 and 3 in the second trial, which had a 1 cm difference in balloon circumference, where the flask which was 19 cm away (flask 3) from the light measured 1 cm less than the fla The fact that these data do not precisely follow the pattern could be a result of measurement uncertainty. For instance, when measuring the volume of water, even if the graduated cylinder had a 0.1 ml error, parallax error could have been a factor that led to erroneous results. Despite this, the pattern is still evident, and the correlation is still positive, as we can see from the graph that the balloon's circumference grows as the UV light's distance from it decreases.