Biochem - (Jun/14/2006 )

Hi there

I am a little confused about these questions

the following type of enzyme is used in ox'dn/rd'n reactions

kinase
none are involved in oxidation/reduction reactions
isomerase
phosphatase
dehydrogenase

umm i thought all of them would be...thinking of glycolysis (thats a ox/rd reaction right????)..they are all used such as hexokinase, triose phosphate dehydrogenase, isomerase (for dihydroxyacetone phophate/glyceraldehyde 3-phosphate)...also say for example i talk about hexokinase that is a kinase right cos it transfers a Phosphate group from ATP to form glucose-6-phoshate and then pyruvate kinase why is it called a kinase when it takes a phosphate group away from phosphoenolpyruvate

another one...when talking about muscle cells in aerobic/anerobic conditions are we talking about when a muscle uses Oxygen or not...is this like muscle contraction...what exactly happens under both conditions all i know is that under both conditions it makes ATP...and i assume lactate cos isn't that the build up of say lactic acid when u don't get enough oxygen..umm not sure we we also make acetyl CoA, pyruvate or NADH under anerobic conditions...

one last thing...in glycolysis ATP is produced..in the krebs cycle ATP is produced and in oxidative phosphorylation ATP is produced..sooo is the WHOLE point of cellular respiration to produce ATP...I know this probably sounds like a dumb question but could is that the point of it..produce ATP so the cells of the body can do work...at the very end when the electrons bind to Oxygen (forming water i think)....where does the oxgen come form in the first place?? and is oxygen also the main purpose of cellular respiration??

Thanks for any help
biology_06er

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I am not really sure about what you are exactly asking and the objective of the first question.

However, with regard to your second question: The whole point of glycolysis is to give ATP which is a source of energy. Under anerobic conditions the by product is lactate and the ATP yield is much lower than in aerobic conditions. That is the major difference.

You cannot take just the glycolysis pathway by it self. The body works as an Unit. So u have to follow the products from glcolysis to the TCA cycle. The purpose of these cycles is to provide energy for cells and for bodily funtions. Where do you think energy comes when you are running a short distance for eg a 100 meter dash or a 5-mile marathon. The body constantly switches from the aerobic to anerobic mode.

check this out: http://web.indstate.edu/thcme/mwking/glycolysis.html

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u need to refer a biochemistry book.

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Well, we know that many dehydrogenases oxidize sugars to a keto form (usually coupled by reduction of NAD or NADP), so answer 5 is potentially correct. By the same degree, therefore, answer 2 is suspect right off.

Kinases and phosphatases are involved in adding and removing phosphate groups, so those are not involved in redox reactions, and an isomerase simply changes the arrangement of atoms in a molecule (e.g. changing glucose to galactose or mannose), and does not affect the molecules oxidation state at all.

Answer 5 (dehydrogenase) is correct.

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