Question

The name of the protein that makes alpha 1 --> 6 connections between glucose monomers in glycogen is?
    A.   Glycogen debranching enzyme.
    B.   Glycogen synthase
    C.   Glycogen Phosphorylase
    D.   Glycogen Branching Enzyme

Which cofactor is required to break an otherwise stable carbon-carbon bond?
    A.   NAD+
    B.   Vitamin C
    C.   TPP
    D.   biotin
    E.   FAD

How many strongly endergonic reactions take place in gluconeogenesis?

Most fatty acids are an even number of carbons in length. How many carbon atoms are there in the molecule that contributes most of the carbon atoms to a fatty acid?

Answer 1

ANSWER 1) GLYCOGEN BRANCHING ENZYME

EXPLANATION

Glycogen, a branched polymer of glucose with α(1→4) and α(1→6) linkages, serves as an energy store for many tissues. Its synthesis requires three enzymes: autocatalytic glucosylation of glycogenin, which provides a priming oligosaccharide chain; glycogen synthase, which extends the oligosaccharide chain; and branching enzyme, which is responsible for the synthesis of highly branched polymers

ANSWER 2)

TPP

EXPLANATION

Pyruvate decarboxylase (PDC) is a thiamine pyrophosphate (TPP)-dependent enzyme catalyzing the decarboxylation of pyruvate to acetaldehyde or the transfer of a C2 unit of pyruvate onto acetaldehyde with formation of acetoin. The mechanism of the reaction is believed to occur through the initial formation of an adduct between TPP and pyruvate

4 REACTION ARE HIGHLY ENDERGONIC REACTION IN GLUCONEOGENSSIS

The gluconeogenesis pathway consumes ATP, which is derived primarily from the oxidation of fatty acids. The pathway uses several enzymes of the glycolysis with the exception of enzymes of the irreversible steps namely pyruvate kinase, 6-phosphofructokinase, and hexokinase. The irreversible reactions of glycolysis are bypassed by four alternate unique reactions of gluconeogenisis. The four unique reactions of gluconeogenesis are pyruvate carboxylase, located in the mitochondrial matrix, phosphoenolpyruate (PEP) carboxykinase located in mitochondrial matrix and cytosol, fructose-1, 6-bisphosphatase located in the cytosol and glucose-6-phosphatase located in the endoplasmic reticulum (ER). The pathway leading from pyruvate to glucose-6-phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously.

• In the mitochondrion, pyruvate is carboxylated to form oxaloacetate via the enzyme pyruvate carboxylase. Pyruvate carboxylase requires ATP as an activating molecule as well as biotin as a coenzyme. This reaction is unique to gluconeogenesis and is the first of two steps required to bypass the irreversible reaction catalyzed by the glycolytic enzyme pyruvate kinase.
• In the cytosol, oxaloacetate is decarboxylated and rearranged to form phosphoenolpyruvate (PEP) via the enzyme PEP carboxykinase. PEP carboxykinase requires GTP as an activating molecule and magnesium ion as a cofactor. This reaction is unique to gluconeogenesis and is the second of two steps required to bypass the irreversible reaction catalyzed by the glycolytic enzyme pyruvate kinase.
• 3-phosphoglycerate is phosphorylated via the enzyme phosphoglycerate kinase to form 1,3-bisphosphoglycerate. This reaction requires ATP as an activating molecule.
• 1,3-bisphosphoglycerate is reduced to glyceraldehyde 3-phosphate via the enzyme glyceraldehyde 3-phosphate dehydrogenase. NADH is the electron donor.

ANSWER

Fatty acid synthesis is the creation of fatty acids from acetyl-CoA which is a 2 carbon molecule and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell.