Lab LT: molds

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Lab LT: molds
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2014-10-13 17:57:17
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  1. Illustrate and label the different parts of a mold.
  2. Differentiate between sexual and asexual means of reproduction of fungi.
    When bacteria become resistant to antibiotics it is called antibiotic resistance. Some bacteria are naturally resistant to some antibiotics. This is the reason why many different kinds of antibiotics can be found in our world today. Different kinds of antibiotics are present so that each and every bacterium that can infect a human can be subdued and killed. On the other hand as mentioned before some bacteria are resistant to antibiotics. On of the most common reasons why bacteria are resistant to antibiotics is the improper taking of antibiotics of a human host. If the human host does not follow the prescribed time of taking the antibiotic and just stops immediately then not all the bacteria die. Some of the more resistant bacteria remain inside the host and can multiply thus the host will contain millions of bacterial cells that would be resistant to that specific antibiotic. In addition to this there is a possibility that the resistant bacterial strain contained in the person can spread to other people thus infecting more hosts for this certain bacterial strain. On the other hand some bacterial cells can mutate in order for the antibiotic to be ineffective against them. One mutation is called the vertical gene transfer. Simply put in a population of bacterial cells as it grows, a small percentage of the cells will naturally develop a resistance to the antibiotic. The number of these cells might be low at first but it is important to note that most bacteria can multiply to a large amount in a short amount of time. As a result of this the number of resistant bacteria can grow very large since the genes of resistance can be passed on to the organisms next generation during dna replication. Another mutation can happen through Horizontal gene transfer, contrasts with vertical gene transfer. The resistance of the antibiotic is not passed to the organisms next generation rather the resistance is gathered from another organism. Conjugation can be an example of this process when two bacterial cells exchange dna information. Another is transformation; this is when the cell takes the dna resistance from the external environment. Lastly is transduction this is when bacteria-specific viruses transfer dna between two closely related bacteria4. What is the importance of the positive and negative control?The positive and negative control, are your controlled results during the experiment. The positive control shows you the proper result when a antibiotic disk is placed in the dish. A positive result shows that there is an area of inhibition. On the other hand the negative control shows the effect if not antibiotic is present in the disk placed in the dish. A zone of inhibition would not be present in the disk. These controlled results serve as your benchmarks during the experiment. It can show you what results to expect with your experimental reagents.2. Sexual reproduction is known to occur in all groups of fungi except the Fungi imperfecti or Dueteromycetes. It may involve fusion of gametes, gametangia or hyphae. The process may involve only fusion of cytoplasm (plasmogamy) or fusion of nuclei (karyogamy) or production of meiotic spores (meiospores)In most of the lower fungi plasmogamy is immediately followed by karyogamy and meiosis. In higher fungi karyogamy is often delayed so that the hyphae remain dikaryotic. This phase of fungal life cycle is called dikaryophase. Such fungi complete their life cycle in three phases a haplophase, a dikaryophase and a diplophase.Asexual reproduction is the type of reproduction in which special reproductive structures called spores or propagates are formed. The fungal spores always result from mitosis and hence are described as mitospores.
  3. Enumerate and give the characteristics of the different kinds of sexual spore of fungi and give several examples of each.
    • spores of Basidomycota: 
    • Formation of the sexual spores of the Basidiomycota differs among these different groups. In principle, plasmogamy takes place in isolation, leading to the formation of a dikaryotic hypha. Karyogamy need not proceed for some time. Diploid hyphae may coexist with haploid and dikaryotic hyphae in one thallus. During formation of the fruit body, basidial initials are formed. Nuclei pass through meiosis in the swollen probasidium. The resultant haploid nuclei pass through the o
    • spores of zygomycota: 
    • The sexual spore of the Zygomycotina and several other groups is diploid. Spore formation is initiated with hormonal interaction between hyphae of opposite mating types. LINKZygospore of Endogone.Plasmogamy follows elongation of laterals towards each other. The Zygospore is formed following gametangial contact. The haploid nuclei from each mating type fuse (karyogamy) to form the diploid nucleus. The zygospore is formed inside a sporangium, and usually only one spore is found in each zygosporangium. Meiosis takes place immediately prior to germination of the zygospore, and the emerging thallus is haploid.

    The haploid sexual spores of the Ascomycota are formed inside an ascus. Spore formation is initiated following hormonal interaction between hyphae of different mating types. Following plasmogamy, the two haploid nuclei exist in a dikaryon for a short period. The cell multiplies using a crozier in the most complex patterns, and eventually the nuclei in apical cells fuse (karyogamy) and immediately pass into meiosis inside the ascus initial.
  4. Aside from PDA, give other culture media that can be used to isolate moles.
    Malt Agar, Rose Bengal Agar, Oxytetracyclin Glucose Yeast Extract Agar (OGY Agar), Yeast Extract Glucose chloramphenicol Agar (YGC agar)
  5. Aside from the moist chamber technique, give other methods by which once can isolate molds.
    Direct Transfer: This isolation method would be useful if the growth of the molds would be visualized. The object that would be the place of the growth of molds would be placed under a dissecting microscope and an inoculating needle is heated, cooled then used to get some spores into a sterile plate of culture medium. Direct Plating: This method is used to rapidly spread molds and fungi with the use of a nutrient agar medium. Pieces of substance where the molds will grow are placed on the surface of the agar. This method is usually used for soil studies that only requires a pinch of soil that is dispersed over the surface of the agar. Dilution Plating: In this technique 1 gram (dry weight) of the material to be studied is ground up (if necessary) and dispersed in 9 ml of sterile water. One millilitre of this solution is transferred to a second tube containing 9 ml of sterile water, resulting in a 0.01 dilution of the spore mass in the original material. The process is repeated to yield dilutions of 0.001, 0.0001, and 0.00001 or even further if necessary. A 1-ml portion from each dilution is pipetted to a separate Petri dish, and cooled, melted agar medium poured over it. The plate should be moved gently on the table in a figure-of-eight motion to effect proper dispersion. Alternatively, the solution can be put on the surface of solidified medium and spread evenly throughout.
  6. What are some reasons becteria are becoming resistant to antibiotics?
    When bacteria become resistant to antibiotics it is called antibiotic resistance. Some bacteria are naturally resistant to some antibiotics. This is the reason why many different kinds of antibiotics can be found in our world today. Different kinds of antibiotics are present so that each and every bacterium that can infect a human can be subdued and killed. On the other hand as mentioned before some bacteria are resistant to antibiotics. On of the most common reasons why bacteria are resistant to antibiotics is the improper taking of antibiotics of a human host. If the human host does not follow the prescribed time of taking the antibiotic and just stops immediately then not all the bacteria die. Some of the more resistant bacteria remain inside the host and can multiply thus the host will contain millions of bacterial cells that would be resistant to that specific antibiotic. In addition to this there is a possibility that the resistant bacterial strain contained in the person can spread to other people thus infecting more hosts for this certain bacterial strain. On the other hand some bacterial cells can mutate in order for the antibiotic to be ineffective against them. One mutation is called the vertical gene transfer. Simply put in a population of bacterial cells as it grows, a small percentage of the cells will naturally develop a resistance to the antibiotic. The number of these cells might be low at first but it is important to note that most bacteria can multiply to a large amount in a short amount of time. As a result of this the number of resistant bacteria can grow very large since the genes of resistance can be passed on to the organisms next generation during dna replication. Another mutation can happen through Horizontal gene transfer, contrasts with vertical gene transfer. The resistance of the antibiotic is not passed to the organisms next generation rather the resistance is gathered from another organism. Conjugation can be an example of this process when two bacterial cells exchange dna information. Another is transformation; this is when the cell takes the dna resistance from the external environment. Lastly is transduction this is when bacteria-specific viruses transfer dna between two closely related bacteria
  7. 4. What is the importance of the positive and negative control?
    The positive and negative control, are your controlled results during the experiment. The positive control shows you the proper result when a antibiotic disk is placed in the dish. A positive result shows that there is an area of inhibition. On the other hand the negative control shows the effect if not antibiotic is present in the disk placed in the dish. A zone of inhibition would not be present in the disk. These controlled results serve as your benchmarks during the experiment. It can show you what results to expect with your experimental reagents.

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