Six glycolysis problems worked to completion for NS230 Unit 3: net ATP, NADH fate, entry from glycogen and fructose, the red cell shunt, and the regulated steps. Searches like "ns 230 unit 3 assignment example", "ns230 unit 3 sample" and "ns230 unit 3 example" land here.
What a finished NS230 Unit 3 glycolysis problem set looks like
Each problem appears as question, reaction table, tally and a one-line conclusion. Problem one lists the ten steps with the two ATP invested at hexokinase and phosphofructokinase-1 and the four recovered at phosphoglycerate kinase and pyruvate kinase, for a net of two ATP and two NADH per glucose. Problem two starts from muscle glycogen, where phosphorylase releases glucose-1-phosphate without spending ATP, so the net rises to three. Problem three sends pyruvate to lactate in a red blood cell and shows lactate dehydrogenase regenerating the NAD+ that glyceraldehyde-3-phosphate dehydrogenase consumed. Problem four brings fructose into the liver through fructokinase and aldolase B, entering below the phosphofructokinase-1 control point. Problem five runs the 2,3-bisphosphoglycerate shunt and counts the ATP forfeited, and problem six asks which three steps set the rate.
How a NS230 Unit 3 example is structured
A short key opens the set: the ten reactions in order, with the three irreversible steps, hexokinase or glucokinase, phosphofructokinase-1 and pyruvate kinase, flagged, and the convention for counting ATP stated once. Problems then run from the plain tally toward the ones that change it. Every problem shows its reaction table rather than a bare number, letting the grader follow each ATP and NADH into the count. Carbon is tracked alongside energy: six carbons in, two three-carbon pyruvates out, with the split at aldolase marked. Regulation gets a problem of its own instead of scattered comments, naming what activates or inhibits each control enzyme, including fructose-2,6-bisphosphate and citrate at phosphofructokinase-1. A closing paragraph states which answers change under anaerobic conditions and which do not. The course text supplies every value cited.
Invest two, recover four
The first problem sets the pattern every later one follows: ATP spent, ATP made, NADH produced, each attached to a named step in the ten-reaction table.
Glycogen changes the count
Starting from a glycogen glucose skips the hexokinase ATP, so the net climbs to three. The problem names phosphorylase and the inorganic phosphate it uses instead.
Where the NAD+ comes back
Without oxygen or mitochondria, lactate dehydrogenase restores NAD+ so glycolysis can continue. The red cell problem makes that dependence explicit.
Fructose enters below the gate
Liver fructose skips phosphofructokinase-1 entirely, which the set uses to show why fructose flux in the liver escapes the usual brake.
Three control points, named
The final problem lists the irreversible steps with their activators and inhibitors, and states which respond to energy charge and which to hormones.
Where marks go in NS230 Unit 3
Sets lose most on a net yield given without the tally behind it: 'two ATP' is right and still earns little when the grader cannot see the two invested and the four made. Counting NADH as ATP inside glycolysis, before any shuttle or oxidative step has been specified, is the next frequent deduction, since the prompt usually asks for glycolysis alone. The glycogen problem catches many papers that subtract a hexokinase ATP that was never spent. Fructose problems slip when fructose is routed through phosphofructokinase-1 in the liver, which defeats the purpose of the question. Regulation answers lose credit when they name hormones without the enzyme they act on, or call every step regulated. Carbon miscounts around aldolase, and dihydroxyacetone phosphate left unconverted, cost points in most sections.
Get a NS230 Unit 3 example written to your instructions
Attach the Unit 3 problems exactly as your instructor set them, along with the rubric and whatever ATP counting convention the course uses. Every problem is worked on those terms, reaction table and tally shown, and returned in 24-48h. Nothing is charged for the first sample, regulation questions included if your set has them.
NS230 Unit 3 questions, answered
Should NADH be converted to ATP in the answer?
Only if the prompt asks for the complete oxidation of glucose. For glycolysis alone, report two NADH as NADH. If a later part of the set does carry them through, state the shuttle assumed, since the malate-aspartate and glycerol phosphate routes yield different amounts, and cite the figures your text uses. Mixing conventions within one set is a common source of lost points.
Why does starting from glycogen give three ATP?
Because glycogen phosphorylase uses inorganic phosphate, not ATP, to release glucose-1-phosphate, which is then isomerized to glucose-6-phosphate. The hexokinase step, and the ATP it would spend, is skipped. The rest of the pathway is identical, so the net rises from two to three. Show that reasoning in a line; a bare three with no explanation reads as memorized.
How much regulation belongs in a Unit 3 set?
Enough to name the three irreversible steps and the main effector on each: glucose-6-phosphate on hexokinase, ATP, AMP, citrate and fructose-2,6-bisphosphate on phosphofructokinase-1, and fructose-1,6-bisphosphate feeding forward to pyruvate kinase. Hormonal control usually gets its own unit later in the term, so a sentence noting that insulin and glucagon act through these enzymes is enough here.