m7 Module Seven: Protein Degradation and Synthesis

These flashcards cover key concepts related to protein degradation, synthesis, and associated metabolic pathways addressed in Module Seven.

What are the two main pathways for protein degradation at the cellular level?

The two main pathways for protein degradation are lysosomal degradation (non-specific) and proteasomal degradation (specific).

What is the function of lysosomes in protein degradation?

Lysosomes help break down proteins in an acidic environment using specific proteases.

What is the role of ubiquitin in proteasomal degradation?

Ubiquitin acts as a tag for proteins destined for degradation by the proteasome.

What is the significance of the proteasome in a cell?

The proteasome is a large complex that specifically degrades tagged proteins into smaller peptides.

What happens to amino acids after protein degradation?

Amino acids can be recycled for new protein synthesis or broken down for energy production through various metabolic pathways.

What is the term for the cycle that converts ammonia into urea for excretion?

The urea cycle.

What pH condition is required for the activation of pepsin during protein digestion?

An acidic environment, provided by hydrochloric acid (HCl) in the stomach.

What happens in the duodenum after chyme is released from the stomach?

The pancreas releases bicarbonate to neutralize the acidity, allowing proteolytic enzymes to activate and further degrade proteins.

What is the role of enteropeptidase in protein digestion?

Enteropeptidase activates trypsinogen into trypsin, starting a proteolytic cascade to further digest proteins.

What occurs during the process of deamination of amino acids?

The amine group is removed, producing ammonia and a carbon backbone that can enter other metabolic pathways.

How does nitrogen fixation relate to amino acid metabolism?

Nitrogen fixation allows for the integration of nitrogen into organic molecules, which is essential for the synthesis of amino acids.

What are the four mechanisms that regulate the degradation of proteins via the proteasome?

1. Cleavage of the N-terminal amino acids, 2. Phosphorylation of the target protein, 3. Phosphorylation of E3 ligase, 4. Binding of specific activators to E3 ligase.

What is the outcome of hyperammonemia?

Hyperammonemia can lead to neurological problems such as seizures, tremors, and poor coordination due to the toxicity of excess ammonia.

What therapeutic intervention is used for patients with urea cycle disorders?

Patients may be treated with phenylbutyrate to help excrete excess nitrogen as phenyl acetyl glutamine.

What is the Cori cycle?

The Cori cycle is the process of converting lactate from muscles back into glucose in the liver during exercise.

How does the urea cycle interconnect with the citrate cycle?

Byproducts of the urea cycle, such as fumarate, can enter the citrate cycle, linking the two metabolic pathways.