Concept Integration Project – Part 1,
Question 1 Juliet Williams, Biology
181 - Capco
What is the relationship between” Endomembrane System, Insulin and
Insulin Receptor, activation by phosphorylation, membrane-bound
polyribosomes, and Glucose Transport Channels? Describe what you learned
about the gut and nutrient absorption in the microscopy lab.
The Endomembrane system is formed by the plasma membrane and the
cytoplasmic organelles (Golgi apparatus, secretory granules, vesicles,
lysosomes, endosomes and the Endoplasmic Reticulum. The main function of
this unit is to ensure macromolecules are transferred from one section of the
cell and cell exterior to another section. What happens if the nuclear
envelope malfunctions and there are defects? Diseases arise such as
Diabetes which is the imbalance of blood glucose caused by insulin
deficiency or the desensitizing of insulin receptors.
Insulin is a hormone that controls lipid and glucose breakdown and
absorption. Insulin is produced in the Endoplasmic Reticulum and travels
through the endomembrane system.
Tyrosine kinase, an insulin receptor is triggered by insulin
Insulin activates the insulin receptor tyrosine kinase and it phosphorylates
and recruits different substrate adaptors. (Webb, Ashley 2016)
Membrane bound polyribosomes are attached to the Endoplasmic Reticulum.
When a ribosome produces insulin, they become membrane-bound". (Nature
Education, 2014) The newly produced insulin polypeptide chains are placed
directly inside the endoplasmic reticulum by the ribosome and transported
to various locations.
Proteins (insulin) is produced by “bound ribosomes” which is used within the
cell membrane or ejected from the cell by exocytosis. The preproinsulin
gene product is synthesized by polyribosomes bound to the ER of insulin-
producing cells. When glucose is high then insulin synthesis is activated.
More message is bound to ER membranes which is located in the cell
cytoplasm. (Pearson, Chapter 9)
Insulin regulates glucose uptake into adipose tissue and skeletal muscle
through glucose transport channels. Vesicles that contain glucose
transporters are aligned to the plasma membrane by insulin activation which
causes the glucose to be transported into the cell.
Gut and Nutrient Absorption:
