KINESIOL 1AA3 Lecture Notes - Lecture 28: Pancreatic Islets, Pancreatic Juice, Pancreatic Polypeptide

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harlequinsalmon796

22 Apr 2019

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2 types of cells: ancini- act as exocrine gland (products into ducts), secrete pancreatic juice to aid in digestion, pancreatic islets- islands in the middle of the ancini. Glucagon and insulin secretions are humoral control because it"s a change in the blood concentrations. insulin secretion: f cells produce pancreatic polypeptide, which acts to inhibit somatostatin and induce contractions within the digestive tract. Insulin: after a meal, blood glucose concentrations rise and an increase in insulin which goes and binds to a membrane receptor on the target cell. Control of blood glucose concentration (glucagon and glycogen) Insulin goes and binds to the insulin receptor, signalling cascade happens insulin dependent signalling cascade which causes glut4 to move out to the plasma membrane so that glucose can enter the cell. Exercise increases the sensitivity and number of receptors as well as the glut4 number (amplified signal)

Related Questions

Pancreatic beta cells secrete the hormone insulin to regulate blood glucose levels. Which of the following organelles are beta cells most likely to have in abundance and why?

	a.	Mitochondria â because insulin is also used to synthesize ATP
	b.	Peroxisomes â because excess insulin must be recycled to avoid toxic levels
	c.	Smooth ER â because insulin is a steroid hormone like testosterone
	d.	Centrosomes â because extra microtubules are needed for insulin transport
	e.	Plasmodesmata â because insulin is secreted through plasmodesmata in the cell membrane.
	f.	Rough ER â because insulin is a secreted protein synthesized by bound ribosomes

(BIOCHEMISTRY QUESTION)

A. Gluconeogenesis is not just the reverse of glycolysis. Briefly describe one of the steps catalyzed by different enzymes in glycolysis and gluconeogenesis.

B. Explain how a biochemist might dicover that a certain enzyme is allosterically regulated.

C. What are the regulatory implications for the cell with regard to ATP & AMP, given the relative concentrations of ATP & AMP in a cell?

D. Describe the function of fructose 2,6-bisphosphate in overriding the control of gycolysis and gluconeogenesis in liver cells in response to lowered blood glucose levels.

E. The human disease beriberi is caused by a deficiency of thiamine in the diet. People with severe beriberi have higher than normal levels of pyruvate in their blood & urine. Explain this observation in terms of specific enzymatic reaction(s).

My Responses: Could you tell me if these are correct? If not, could you provide the correct answer and explanation?

A. Its a cellular process in which glucose is produced from pyruvate, amino acids, lactate, and other biogenic precursors.

B. They might learn that an enzyme is allosterically regulated if that protein or enzyme undergoes a conformational change modulated by the binding of one or more modulators/effectors to alternate sites on the protein, resulting in a change in its activity. And they usually have more than one polypeptide chain.

C. The regulatory implications for the cell would be that all activity would increase and concentrations would go up unless bound to PFK-1 and then the overall activity would drop.

D. Low blood glucose is when glucagon signals the liver to produce and release more glucose (gluconeogenesis) and stop consumption. Fructose 2, 6-bisphosphate mediates rapid hormonal regulation of glycolysis and gluconeogenesis.

E. Pyruvate is the product of both carbohydrate and amino acid catabolism that enters cellular respiration in the mitochondria when converted to acetyl-CoA catalyzed by the PDH complex. The first step in the PDH complex reaction is a decarboxylation reaction that cannot be catalyzed without the enzyme thiamine pyrophosphate (TPP). This coenzyme is a derivative of thiamine or vitamin B1.

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KINESIOL 1AA3 Lecture Notes - Lecture 28: Pancreatic Islets, Pancreatic Juice, Pancreatic Polypeptide

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