Concept explainers
To explain: What happens when Neurospora spores are exposed to X-rays and a culture is established from the irradiated spores and then grown in (1) a minimal medium plus vitamins, (2) a minimal medium plus amino acids, and (3) a minimal medium.
Introduction: Genes are sets of
To explain: What happens when Neurospora spores are exposed to X-rays and a culture is established from the irradiated spores and if the
Introduction: Genes are sets of nucleotides that code for a particular protein. The genes have to be expressed for the synthesis of a protein. This gene expression is regulated depending on the requirement of the cell. For example, cell division proteins are synthesized prior to the cell division. Prokaryotic and eukaryotic genes have differential gene expression in order to suit the specific needs of the cell.
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Chapter 13 Solutions
Biology (MindTap Course List)
- In a biological production process, bacteria with spore-forming ability are immobilized on a support surface. Once a batch of production is done, these cells along with their support material are separated from the medium, and then sterilization is performed in a furnace for safe disposal of material into the environment. An important issue here is to ensure ALL bacteria, including any spores that may form and those that are located at the center of the spherical support material, are killed with heat. For this purpose, the temperature at the center of the spherical support material must reach the designated killing temperature. The support material is a sphere with 3 cm diameter and a heat capacity of 4.0 kJ/kg*K, a density of 800 kg/m³, a thermal conductivity of 0.7 W/m*K. The heat transfer coefficient of the surrounding air is 14 W/m2*K. If the initial temperature inside the furnace prior to the start of sterilization is 15 °C, how long should the procedure last to obtain sterile…arrow_forwardCarefully observe the cell morphology of the two organisms below. Then, draw the cell morphology. Cells should be drawn large enough so that you can show an accurate shape and arrangement. Your drawing should capture the relative length and width of the cells. There should be no pointy corners, no open circles, no extra “tails” and no overlapping rings. Specify cell morphology and if the organism a) Escherichia coli or b) Staphylococcus aureusarrow_forwardYour lab coordinator has decided to grow and maintain a sourdough starter. A sourdough starter is a live, on-going culture of yeast that is grown in flour, water, and a bit of sugar. It is used as an ingredient in some types of bread. This is the question : How does it accumulcate another species? You have been asked to take this mixed culture and isolate the different species in the starter (which is basically a liquid culture). How will you do it?arrow_forward
- Alexander Fleming was working with bacteria called staphylococcus, which looked like bunches of grapes under the microscope. He could grow colonies of these bacteria on petri dishes with a growth medium. When he returned from vacation, he found that several of these dishes had become contaminated with a fungus. The colonies near where the fungus was growing had been destroyed. Fleming then grew the mold and purposefully added it to a petri dish that contained bacteria colonies. The colonies exposed to the mold died. Fleming named the substance within the mold that killed bacteria "penicillin." REASONING: If mold contains a substance that kills bacteria, then ... a) bacteria exposed to mold would be destroyed b) bacteria could be grown on a growth medium c) fungus can be grown as easily as bacteriaarrow_forwardThe death of Geobacillus stearothermophilus spores is routinely used to assess the effectiveness of sterilization procedures. In this procedure, endospores are exposed to the sterilization process (e.g., autoclaving) and then plated on germination medium. If sterilization has been successful, no growth occurs. This requires about 2 days. Yung and Ponce have developed a new approach that yields results within 15 minutes after sterilization. Their technique is based on the release of dipicolinic acid (DPA) from the spore coat by germinating cells. DPA release is monitored microscopically after endospores are placed in media containing alanine and terbium ion (Tb31). Alanine triggers germination and Tb31 binds DPA, which then fluoresces green when illuminated with UV light. Design an experiment in which this new method could be shown to be as reliable as the culturebased approach. What other sterilization procedures besides autoclaving could this technique be used to monitor?arrow_forwardWhich of the following is the best definition of generationtime?(a) The length of time it takes for lag phase to occur(b) The length of time it takes a population of cells to double(c) The minimum length of time it takes a cell to divide(d) The length of time a culture stays in stationary phase(e) The length of time it takes log phase to occurarrow_forward
- Select five (5) different isolated colonies in the illustration below and fully characterize each of them by describing their texture, transparency, color, and form (size, overall shape, margin, and elevation). Crop each colony you have chosen and tabularize your answer.arrow_forwardThere are two cultures of yeast cells in the pictures, one has been incubated for 6 hours and one has been incubated for 24 hours. After a 10x dilution by taking 100µl of each culture and adding it to 900 µl water in a microcentrifuge tube and 100µl sample from the tube was taken to view in the counting chamber. a) Count the total number of yeast cells for each culture respectively b) Calculate the concentration and density of yeast cells for each culture respectivelyarrow_forwardWhich of the following methods used to enumerate cells often requires specialized staining to observe nonpigmented bacteria? A) Spectrophotometry/turbidity B) Spread-plating C) Microscopy D) Spread-plating, turbidity, and microscopyarrow_forward
- In 1971, Dr. Akira Endo, working at the Sankyo company in Tokyo speculated that fungi not only contained antibiotics but also inhibitors of other processes such as cholesterol metabolism. Over a period of several years, he screened more than 6,000 fungal cultures until a positive result emerged. This compound, which was named compactin, came from the blue-green mold Penicillium citrinum Pen-5 that was isolated from a rice sample collected at a grain shop in Kyoto. Based on biochemical assays, compactin is the first known statin. 1. The original kinetics data for compactin inhibition of HMG-CoA reductase enzyme that was published by Dr. Endo in 1976 is shown on the right. a) Determine the Km and Vmax values for enzymatic activity. Do NOT forget the units. Answers can be expressed either as a fraction or in decimals. With No inhibitor: ; Vmax= -60 1/V, (nanomoles/min)-1 0.4 0.35+ 0.3 0.25 0.2 0.15 0.1 0.05 -40 -20 0 + 24 nM compactin + 70 nM compactin None T 20 40 60 1/[HMG-CoA], (mM)-1…arrow_forwardGeorge Beadle and Edward Tatum studied the common bread mold, Neurosporacrassa, in the early 1940s They detected a link between gene mutations and proteins They used X-rays to generate mutations that were unable to survive on minimal medium though they could grow on complete medium(supplemented). Design an experiment that would enable you to pinpoint the mold/mildew with the resistance distinct from the ones without the resistance.arrow_forwardComplete the colony morphology for the colonies pictured above: 1. Form - 2. Elevation - 3. Margin - 4. Surface - 5. Chromogenesis -arrow_forward
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