2. a) Outline the synthesis of glycogen (include all the reactions) and their respective enzymes

Glycogen synthesis, also known as glycogenesis, is a process that involves multiple steps and enzymes. Here is a step-by-step outline of the process:

1. Glucose Activation: The first step in glycogen synthesis is the phosphorylation of glucose by the enzyme hexokinase to form glucose-6-phosphate (G6P). This step is important because it traps glucose inside the cell and prepares it for further reactions.

2. Isomerization: The enzyme phosphoglucomutase converts glucose-6-phosphate into glucose-1-phosphate (G1P). This is an isomerization reaction, meaning the functional group of the molecule is rearranged but the molecular formula remains the same.

3. Activation of Glucose-1-Phosphate: The enzyme UDP-glucose pyrophosphorylase catalyzes the reaction of glucose-1-phosphate with UTP (uridine triphosphate) to form UDP-glucose, an activated form of glucose. This reaction also produces pyrophosphate (PPi), which is then hydrolyzed by the enzyme pyrophosphatase to provide the energy needed for the reaction.

4. Glycogen Chain Elongation: The enzyme glycogen synthase catalyzes the transfer of glucose from UDP-glucose to the non-reducing end of the glycogen chain. This reaction forms a α-1,4-glycosidic bond and elongates the glycogen chain.

5. Branch Formation: Every 8-12 glucose units, the enzyme branching enzyme (also known as amylo-(1,4→1,6)-transglycosylase) transfers a block of about 7 glucose residues from the non-reducing end of the glycogen chain to an internal glucose residue of the same or another glycogen chain. This forms a α-1,6-glycosidic bond and creates a branch in the glycogen molecule.

6. Further Elongation and Branching: Steps 4 and 5 are repeated, leading to further elongation and branching of the glycogen molecule.

This process continues until the glycogen molecule reaches a size of about 30,000 glucose units. The highly branched structure of glycogen allows for rapid glucose release when energy is needed by the cell.

Glycogen synthesis, also known as glycogenesis, is a process that involves multiple steps and enzymes. Here is a step-by-step outline of the process:

1. Glucose Activation: The first step in glycogen synthesis is the phosphorylation of glucose by the enzyme hexokinase to form glucose-6-phosphate (G6P). This step is important because it traps glucose inside the cell and prepares it for further reactions.

2. Isomerization: The enzyme phosphoglucomutase converts glucose-6-phosphate into glucose-1-phosphate (G1P). This is an isomerization reaction, meaning the functional group of the molecule is rearranged but the molecular formula remains the same.

3. Activation of Glucose-1-Phosphate: The enzyme UDP-glucose pyrophosphorylase catalyzes the reaction of glucose-1-phosphate with UTP (uridine triphosphate) to form UDP-glucose and pyrophosphate. This step activates glucose-1-phosphate for glycogen synthesis.

4. Glycogen Chain Initiation: The enzyme glycogenin, a self-glycosylating protein, catalyzes the addition of the first few glucose units to itself, forming a short primer for glycogen synthesis.

5. Chain Elongation: The enzyme glycogen synthase catalyzes the addition of UDP-glucose to the non-reducing end of the glycogen chain. This enzyme can add many glucose units, allowing the glycogen chain to grow.

6. Branch Formation: The enzyme branching enzyme (also known as amylo-(1,4 to 1,6)-transglycosylase) cuts a segment of the glycogen chain and attaches it to a different glucose residue, creating a (1,6)-glycosidic linkage and forming a branch. This branching increases the solubility and availability of glucose for degradation.

7. Chain Termination: The process of glycogen synthesis is regulated and can be terminated when the cell has enough glycogen stored. This is controlled by various hormones and signaling pathways.

Each of these steps is regulated by different enzymes and factors, ensuring that glycogen synthesis occurs when it is needed by the cell.