User:Ariana Leonelli/Notebook/Biology 210 at AU
February 16 : Third Lab Entry - Microbiology and Identifying Bacteria with DNA (Lab 3 originally on January 29)
The main objectives of this lab were to understand the characteristics of bacteria, to observe antibiotic resistance, and to understand how DNA sequences are used to identify species. The three objectives that I have stated were accomplished by the following three procedures described below.
Procedure 1: Quantifying and Observing Microorganisms - We needed to first make another set of observations from our transects that we had made on the first lab of the semester. After we had done that, we then needed to observe the petri dishes that we had prepared the previous class from the serial dilutions of the Hay Culture. We needed to observe all seven dilution plates, four of which with a nutrient agar, and three of which with a nutrient and tetracycline (antibiotic) agar. For each petri dish we had to record the number of colonies in each dish and record them in a table.
Hay Culture Observations: -some water evaporated -smell not as potent -water looks darker throughout -still some green shoots -debris is still on bottom -no section like division this time; one big mess in there
Petri Dish Observations: 10^-3 (nutrient only) : counted approximately 1940 colonies which converts to approximately 1,940,000 colonies per ml 10^-5 (nutrient only) : counted approximately 150 colonies which converts to approximately 15,000,000 colonies per ml 10^-7 (nutrient onliy) : counted approximately 6 colonies which converts to approximately 60,000,000 colonies per ml 10^-9 (nutrient only) : counted approximately 0 colonies which converts to approximately 0 colonies per ml 10^-3 (nutrient and tet) : counted approximately 50 colonies which converts to approximately 50,000 colonies per ml 10^-5 (nutrient and tet) : counted approximately 3 colonies which converts to approximately 300,000 colonies per ml 10^-7 (nutrient and tet): counted approximately 0 colonies which converts to approximately 0 colonies per ml
Procedure 2: Antibiotic Resistance - In this procedure we were required to observe our petri dishes once again along with our recorded table in order to make comments about the appearances and differences in between the plates with nutrient agar and the plates with nutrient and antibiotic agar. After observing all of the collected information, my group noticed the following: Plates with Nutrient Only: no fungi, more colonies, smaller colonies, mostly mily and white colored ones. Plates with Nutrient and Antibiotic: fungi present, less colonies, larger colonies, no clear colored bacteria, pink and orange bacteria. When looking at the differences between the two plate types, I notice that the plates without the antibiotic have more abundant, smaller bacteria. Even though there still are baterica on the plates with antibiotic, there are not as many so it would be safe to assume in this case that the antibiotic and nutrient agar inhibits bacterial growth on the dish. However, based on my observations I would also suggest that the addition of the antibiotic allows for fungal growth which is not seen on the plates without tetracycline. Based on my dishes and my observations I would also say that orange and pink bacteria are unaffected by the tetracycline since they still appeared on those dishes. "Tetracycline works by binding specifically to the 30S ribosome of the bacteria, preventing attachment of the aminoacyl tRNA to the RNA-ribosome complex. It simultaneously inhibits other steps of the protein biosynthesis. Tetracycline can also alter the cytoplasmic membrane and this in turn causes leakage of nucleotides and other compounds out of the cell. This does not directly kill the bacteria but instead inhibit it." (quote from http://www.chm.bris.ac.uk/motm/tetracycline/antimicr.htm)
Procedure 3: Bacteria Cell Morphology Observations - In this procedure we had to observe different bacteria from our agar plates that we chose after mounting them with oil. We also had to make a gram stain from our different bacteria that we cultured from our agar plates. We were required to record our observations of what three bacteria looked like, which agar plate they came from, what they looked like before we put them under the microscope, number of colonies, their motility and shape, and whether they were gram negative or positive. Below is what we observed.
Bacteria 2: - 10^-7 nutrient plate - circular, flat with distinct circle in middle, dark milky color, not really that smooth - #colonies: about 60,000,000 - cocci, staphylococcus, and streptococcus, no movement - gram negative - Diplobaccili
Bacteria 3: - 10^-5 nutrient plate - orange, circular, convex, smooth - #colonies: about 300,000 - cocci, staphylococcus, no movement - gram negative - Staphylococcus (same as Bacteria 1 just more cells)
February 8 : Second Lab Entry - Identifying Algae and Protists (Lab 2 originally on January 22)
The main objectives of this lab were to understand how to use a dichotomos key and the characteristics of algae and protists. These two objectives were accomplished by completing the two procedures described below.
Procedure 1: How to Use a Dichotomous Key - We needed to be able to look at two samples that we had made wetmounts of in and identify two different types of organisms on each wet mount. We were required to describe what each organism looked like, how big it was, and then identify what it could be by using a dichotomous key. Based on the many questions and images that are available on the dichotomous key, I felt fairly confident that my guesses were correct.
Wet Mount #1:
Organism 1: - long slim, blue-green color - size: 1500 µl - Stentor
Organism 2: - large, creeps using pseudopodia, many small nuclei - size: 150 µl - Pelomyxa
Wet Mount #2:
Organism 1: - long slim, pinkish-rose color - size: 2500 µl - Blepharisma
Organism 2: - oval shaped, contracting w/ lots of nuclei, barely moving - size: 50 µl - Gonium
Procedure 2: Hay Infusion Culture Observations - In this section of the lab me and my transect group needed to observe the transect that we made the previous lab and record what we saw and then observe wet mounts taken from the Hay Infusion to see what organisms were present. We needed to observe three different organisms from each wet mount (we made two). We decided to make a wet mount of the bottom of the Hay Culture, and then a second wet mount from the top of the Hay Culture. Organisms near plant matter could possibly be photosynthetic in nature as opposed to those not near the plants. I would predict that in a couple months the small abount of green growth that was observed would probably become more abundant along with the amount of algae and bacteria that were in our samples. Carrying capacity was definitely a player in the culture because there is no way that more than the maximum amount of organisms possible for that niche size can exist in that environment. If we had observed one of the plants that were in our culture, we would have most definitely been able to identify it as something alive because it can do photosynthesis to get its energy, it is made up of cells, it has genetic information in the nuclei of its cells, the cells can replicate, and they are a product of evolution, most likely evolving from green algae. Below is what we observed / found.
Appearance of Hay Culture: - smells moldy (kind of like a seafood smell) - top is thick with some kind of algae maybe? - sprout of green growth / green shoot on top part of culture - the water is a brownish color - nothing really floating in the middle of the culture - sedement on bottom - white type of filmy liquid is right under the water surface
Top Sample Wet Mount:
Bottom Sample Wet Mount:
2/6/14, lab 1 notes
Great work! Some notes: -Make sure you include pics before Sunday -In the future, weave the answers to the questions into the introduction or discussion section. Do not write question and respond with answer. -Start working on building a map of your transect to detail your land and where your samples are taken from. We will talk about this more Wednesday
Great job!! AP
January 29: First Lab Entry - Biological Life at AU (Lab 1 originally on January 15)
The main objectives of this lab were to understand natural selection and to understand the abiotic and biotic characteristics of a niche. These objectives were accomplished with the two procedures described below.
Procedure 1: The Volvocine Line - We needed to identify the different members of the valvocine line for this procedure and specify the number of cells, colony size, and its reproductive specialization for each of the different members. I predicted that the more advanced along the valvocine line we moved, the more complex what I saw would become. I looked at each of the three options on wet mounts under a microscope using the 4x, 10x, or 40x objective lens in order to figure out the information asked of me. Based on the data collected I was correct in assuming that the genera would become more complex over time. I was able to address the question posed in the beginning of this procedure.
Chlamydomonas: Unicellular, colony size was 7.5µl, isogamy.
Gonium: Eight cells, colony size was 60µl, isogamy.
Volvox: Too many cells to count, all appear to be in a bulb shape, colony size was 125µl, oogamy.
-What is the significance of cell specialization across these three genera? Natural selection is shown through the changes in complexity of these three genera over time.
-Does evolution always move towards increased complexity? Provide an example. No I dont think it necessarily does. People originally have tails which are considered vestigial traits that go away the more they develop in the womb. The lack of tail makes us less complex than if we were to be born with tails.
Procedure 2: Defining a Niche at AU - We were put into groups of three and were sent to observe a transect here at AU. We also were given a 50ml conical tube to collect a soil/surface plant sample to bring back to class to use for the next few labs. In this lab we were asked to record our observations in a notebook to explain what our transect looked like. Once we returned to the lab we needed to make our Hay Infusion Culture by adding 500ml of water and .1g of dried milk to 10-12g of our sample and then close and leave it for next class.
Observations of Transect: (Located in front of Kogod)
Abiotic: Small rocks, larger rocks, big boulders, water, sun, soil
Biotic: Moss, cat tails, grass, weeds, red bark shrub, algae, bacteria, fungi, protists
Also noticed dead bark and leaves. Water runs downhill through transect.
January 22 Successfully entered text ATL