Common baker's yeast (Saccharomyces cerevisiae) is normally grown...

Question

Common baker's yeast (Saccharomyces cerevisiae) is normally grown at 37°C, but it will grow actively at temperatures down to approximately 25°C. A haploid culture of wild-type yeast is mutagenized with EMS. Cells from the mutagenized culture are spread on a complete-medium plate and grown at 25°C. Six colonies (1 to 6) are selected from the original complete-medium plate and transferred to two fresh complete-medium plates. The new complete plates (shown) are grown at 25°C and 37°C. Four replica plates are made onto minimal medium or minimal plus adenine from the 25°C complete-medium plate. The new plates are grown at either 25°C or 37°C and the growth results are shown.

What can you say about colony 4?

Accepted Answer

Welcome back, everyone. Let's look at our next problem. It says the wild type strain of lactobacillus, the bulgari grows best at A P H of 4.5 to 5.5 and 40 to 45 degrees Celsius. This bacterium is commonly used for yogurt production, which is carried out at A P H of 4 to 4.5 at a temperature of 40 to 45 degrees to overcome this hurdle. Scientists decided to mutate a strain of elbow gerica by changing the bacterium's outer membrane protein structure. They found the mutated strain could now survive in P H 4 to 4.5 but is not able to survive beyond 40 degrees. Which of the following statements accurately describes the new mutated strain of lactobacillus bulgari. So we'll read our answer choices and think through them. But before we started on that, I just want to go over and make sure we understand the key points here that we're going to need to evaluate which of the answer choices best describes the new mutant strain. So we have our new mutant strain which we say it now survives in P H 4 to 4.5. One thing that's important to note, it says the mutated strain strain could now survive at this lower P H point. We see the wild type strain is P H 4.5 to 5.5. So the way that is worded doesn't mean that it can no longer survive in 4.5 to 5.5, but that it has an extended lower range. So now it can survive And P H is as low as four, whereas before it had to be 4.5, and then it says it is not, the new mutant strain is not able to survive beyond 40 degrees, whereas our original strain survives from 40 to 45 degrees. So we see that uh yogurt production needed to be carried out at that lower P H 4 to 4.5 where the wall type strain didn't survive. You've now mutated a strain that can handle the lower P H but you've lowered its temperature tolerance. So those are our key differences there. So let's start to read through our answer choices and find the correct one with the best description choice. A says the new mutated strain kangaroo at a wider P H range and higher temperature than the wild type strain. Well, the first part is correct, the new mutated strain does have a wider P H range. It can grow in those lower P H S below 4.5. However, it cannot grow at a higher temperature. It needs a lower temperature than the wild type. So choice A is not correct. Now, let's look at choice B. Choice B says the new mutated strain can grow at a lower P H range than the wild type strain but cannot survive beyond the same temperature range. Well, this is correct. It has a lower P H range in the wall type but can't survive in the same temperature range as high as the wall type. So choice B seems to be our answer to be thorough. We'll keep on reading and looking at our, our other answer. Choices. Choi C says the new mutated strain can grow at a lower temperature range than the wild type strain but cannot survive at the same P H range. Well, this is not correct. It does grow at a lower temperature range but it survives at a lower P H range than the original wild type strain. So choice C is not correct. And then finally, let's look at choice D, the new mutated strain has the same growth characteristics as the wild type strain and does not offer any advantages for yogurt production. Well, this is not correct because it grows at a lower P H which is an advantage for yogurt production, which takes place in that 4 to 4.5 range that the wild type strain could not survive in. So it does have an advantage for yogurt grows at a lower P H and therefore, is not a correct answer. So again, our best description of the new mutant strain of lactobacillus Bulgari is choice B. The new mutated strain can grow at a lower P H range than the wild type strain but cannot survive beyond the same temperature range. See you in the next video.

Key Concepts

Haploidy and Mutagenesis

Temperature Effects on Yeast Growth

Replica Plating and Selection

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