Growth curve for bacteria- exponential phase

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maccha
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Growth curve for bacteria- exponential phase

Post by maccha » Sat Oct 10, 2009 7:09 pm

We were given a question in biology I'm very confused about. So assume a certain type of bacteria consumes only lactose as their source of energy- if you put these bacteria into a medium with a certain amount of lactose and then transferred it to another medium with double the amount of lactose how would the graphs of their exponential phases compare? What I don't know is if the exponential phase for the second medium would just increase in length (as they can go longer with more food) or if it would increase in rate as well?

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mith
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Post by mith » Sat Oct 10, 2009 8:24 pm

assuming you're growing exponentially in either plate, why would the rate increase?
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Accepting hardships as the pathway to peace;
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maccha
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Re: Growth curve for bacteria- exponential phase

Post by maccha » Sat Oct 10, 2009 10:17 pm

Well I'm assuming it wouldn't.. but I don't really know why. Basically what my reasoning has been is that the bacteria can only consume a max amount of lactose at a time.. so if you put more in it would go for longer but not be able to consume more at a time. But my text says that rates of exponential growth are influenced by the composition of the culture medium, so I'm not sure if this falls under that category. I've been thinking that changing the energy source could influence the rate, but just adding more of a certain energy source wouldn't because the cell still has to break down the same thing, which takes the same amount of time? Am I on the right track at all?

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Post by jwalin » Mon Oct 12, 2009 6:40 am

mith wrote:assuming you're growing exponentially in either plate, why would the rate increase?

that is right
to answer maccha
your text is right. but please do no interpret in by taking it to talk about the concentration of one substance. i think it is telling that the presence of other substances can make a difference.
it isn't what you do that matters but it is how you do it

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mith
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Post by mith » Tue Oct 13, 2009 5:37 am

Not sure what the composition means, possibly it goes with your reasoning and they're suggesting the eating rate is not maxed out if you only have one plate?
Living one day at a time;
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Accepting hardships as the pathway to peace;
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