cellular respiration

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mikki
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cellular respiration

Post by mikki » Thu Nov 03, 2005 8:52 pm

I'm trying get a better understanding of a lab I missed on Halloween. (I had to take my 4yr old trick or treating.) The lab was over cellular respiration and the 2nd part was over lactose fermentation. I have no clue what NaF does to yeast fermentation. I do know from reading that yeast cannot metabolize lactose, so it needs the enzyme lactase (lactaid) to help it. Can anyone help me out with this?

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Post by Fried Zygote Sandwich » Fri Nov 04, 2005 2:54 am

Well, I've got a feeling that when you say lactose fermentation you're talking about arearobic resperation that forms lactose as a result of the digestion of glucose (or whatever substrate) without the presence of oxygen.

NaF probably either inhibits or increases the rate of respiration.

Hope that helps.

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Post by thecow135 » Fri Nov 04, 2005 4:44 am

cellular respiration
lactose fermentation
aerobic respiration
anaerobic respiration

arent these things the ones with the priducing ATP through food and goes through the mitochondria without using oxegen?
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Post by MrMistery » Fri Nov 04, 2005 7:20 pm

Do you mean lactic fermentation. This process happens in some cells and it means turning pyruvate into lactic acid(search the forum for detailes). The process takes place in the cytoplasm. However, yeast does not do lactic fermentation, it does alcoholic fermentation.
Also, take note that all sorts of aerobic respiration takes place in the cytoplasm, not in the mitocondria
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Post by sdekivit » Fri Nov 04, 2005 7:36 pm

NaF is probably an inhibitor of one of your enzymes involved in the metabolism.

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Post by mikki » Sat Nov 05, 2005 9:17 pm

Ok here are the lab insturctions:

In this exercise we will examine the effect of inhibitors and enzyme specificity on the fermentation pathway employed by yeast cells. The prodcut of fermentation, CO2, can be collected and measure as an indicator of the respiration rate. The enzyme enolase catalyzes the conversion of phosphoglycerate into phosphoenol pyruvate. This reaction is dependent on Mg ions and is inhibited by flouroide ions (sodium fluoride, NaF, precipitates Mg ions and thus inhibits the pathway.) Fluoride is toxic to humans so HANDLE WITH CARE!

Part 2 of the lab:
The effect of enzyme specificity on yeast respiration will be evaluated using lactose (milk sugar). Baker's yeast is unable to metabolize lactose, which is a dissacharide. The enzyme that will be used in this exercise will demonstrate how non utilizable sugar can be enzymatically converted into a sugar that can be metabolized. Lactaid is a lactase (galactosidase) that breaks apart lactose into the monosaccharides galactose and glucose.

It is hard to answer this questions when you haven't done the lab.
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Post by mikki » Sat Nov 05, 2005 9:50 pm

By the way, I gave her a rough draft of my lab introduction and she wrote this on my paper:

after the sentence "Cellular respiration involves the metabolism of glucose and the process is catalyzed by enzymes." she wrote:

What is fermentation? Components? What's produced?

She goes on to tell me at the bottom of my intro:
You need to give me background on what NaF does to yeast fermentation and how yeast cannot metabolize lactose so it needs the enzyme lactase.
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Post by mikki » Sun Nov 06, 2005 5:29 am

Oh come on, no takers?
I emailed her a question about our hypothesis and this was her reply,

"You should essentially have a hypothesis in mind for each tube in each experiment that you need to discuss in the discussion section. You can make two, big general hypotheses for the two experiments in your introduction, one being about the inhibition affect of NaF of yeast fermentation, the other about the enzyme lactaid (lactase) and its affects on the before mentioned."

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