Growth and Nutrition In Living Organisms 2.doc - Growth and Nutrition In Living Organisms by C Kohn I think it is safe to say that most people know that

Growth and Nutrition In Living Organisms 2.doc - Growth and...

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Growth and Nutrition In Living Organisms by C. Kohn think it is safe to say that most people know that dairy products have to be refrigerated. Leave the milk on the counter and over the course of the day it will become a hotbed of bacterial reproduction by sunset. Leave a can of Coke next to it and while it would be flat, it would still probably be safe to drink (if Coke could ever be considered safe to drink). I would hazard to guess that most people have not thought deeply about why this difference occurs. Why would one common drink go bad so quickly while another keep for years at a time? The answer is that milk was practically designed for cells of all kinds to grow. Quite simply, what worked for one species of mammal worked for all living species of animal and bacterial life. According to leading theories by evolutionary biologists, the development of mammary glands came before live births (instead of eggs). In fact, milk production may have even allowed this change to occur. The only exceptions to this are the monotremes like the platypus, which still both lay eggs and produce milk. In fact we humans, dogs, and other mammals even have the genes for laying eggs, but these have been silenced over time. Milk production meant that adults no longer needed eggs as a source of nourishment for their young, nor did they have to carry food back to them. Animal mothers now simply had to just eat, and they could feed their young. So why is milk so good at growing things, be it bacteria or babies? To understand this, we have to understand basic cellular nutrition. Understanding what allows basic single celled bacteria to grow will help us understand how single-celled embryos become trillion-celled organisms. In turn, this will help us better understand the complex needs of an advanced mammal like the modern dairy cow among other production animals. I The Bacterial Cell To begin, let us consider the simplest living organism – the bacterium. This is really just a very simple biological machine. There are several factors that affect bacterial cell growth and division. The first is temperature. The temperature at which most bacteria grow the most efficiently is called the optimal temperature – this is usually around the human body temperature of 98.6 o . Temperature is crucial because it is a form of energy and as such affects the rate at which biochemical reactions needed for life can occur. Too cold and these reactions do not have the necessary energy to go on. Too warm and these molecules may denature into something else. Make the temperature just right, and we’ll get the maximum rate for a chemical reaction. Another critical factor is pH, or the acidity or alkaline levels present. Most bacteria thrive between 6.7 and 7.5, with 7.0 being neutral. Nutrition also plays a key role in bacterial growth.
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  • Fall '16
  • mrs.anderson

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