Govt. Exams
Entrance Exams
Bone marrow shows the highest pentose phosphate pathway activity because rapidly dividing cells require maximum ribose-5-phosphate for nucleotide (DNA/RNA) synthesis during cell division. While adipose tissue needs NADPH for lipogenesis and RBCs need it for antioxidant defense, bone marrow's continuous hematopoiesis demands the most nucleotide precursors. This is clinically relevant in leukemia and chemotherapy patients.
Type 2 diabetes shows hepatic insulin resistance leading to impaired glycogenesis (reduced glycogen synthesis) and uncontrolled gluconeogenesis (excessive glucose production). This causes elevated fasting glucose despite normal HbA1c if glycemic control improves later. The liver fails to suppress glucose production in response to insulin.
Aldolase A catalyzes the cleavage of fructose-1,6-bisphosphate into DHAP and G3P. Its deficiency blocks glycolysis at this critical step.
After 8-12 hours of fasting, hepatic glycogen depletes. The liver then relies on gluconeogenesis from Cori cycle lactate and amino acids to maintain blood glucose.
Glucagon and epinephrine activate phosphorylation cascades that activate glycogen phosphorylase and inactivate glycogen synthase, promoting glycogenolysis.
Haworth projection depicts the cyclic hemiacetal structure of glucose in its pyranose form, clearly showing the anomeric carbon and ring geometry.
In diabetes, impaired insulin secretion (due to reduced glucokinase in beta cells) leads to inadequate glucose sensing and utilization by tissues despite hyperglycemia.
Cellulose is a β-1,4-linked glucose polymer that humans cannot digest due to lack of cellulase enzyme. It cannot enter glycolysis.
NADPH from the oxidative pentose phosphate pathway is essential for reductive biosynthesis of fatty acids and cholesterol, which occur predominantly in the fed state.
McArdle disease (GSD Type V) results from muscle phosphorylase deficiency. Glycogen accumulates but is structurally normal. Exercise intolerance and myoglobinuria are characteristic.
