Regulation of Metabolism (Jenney) Flashcards
Cells exist as systems that are in what kind of state?
Dynamic, steady
How do cells maintain their state?
By using energy and raw materials provided by a ‘constant’ flux of nutrients.
What do cells use when external nutrient flux wanes?
They use stored raw materials to make energy/building blocks.
How are internal fuel concentrations (i.e. what?) maintained at all times?
The fuel, glucose, is maintained by switching between internal and external fuel sources as needed.
What is the unit of energy?
ATP
How is the unit of energy generated?
By the oxidation of fuels
What is the common redox agent/electron carrier?
NAD(P)H
What carries electrons from catabolism to ETC?
NADH
What carries electrons for anabolism?
NADPH
What are the 7 major metabolic pathways?
Glycolysis Gluconeogenesis Glycogen metabolism Fatty acid metabolism Citric acid cycle Oxidative phosphorylation Amino acid metabolism
Which metabolic pathways can the liver carry out?
All of them.
How does regulation of metabolic pathways occur?
Compartmentalization inside the cell
Reciprocal regulation of metabolic pathway enzymes
Organ specialization
Hormonal regulation
What is the primary fuel of the brain?
Glucose
Under prolonged starvation, the brain uses what for fuel?
Ketone bodies for up to 70% of energy.
Which glucose transporter is used by the brain?
GLUT3
[Glucose] > ___ leads to coma and death?
2.2 mM
What molecules can cross the blood-brain barrier that can be used by the brain as fuel? Is this common?
Medium chain fatty acids - typically doesn’t happen, but it can.
What does muscle use as fuel sources?
Glucose, fatty acids, ketone bodies
What does the muscle store its fuel as?
Glycogen
How does the Cori cycle work?
Pyruvate becomes lactate to regenerate NAD+ for glycolysis. Lactic acid and decreased pH decrease efficiency, so the lactate is released to the blood, where it travels to the liver to undergo gluconeogenesis.
In resting state, how much of muscle energy comes from fatty acids?
85%
During starvation or excessive activity, amino acids are broken down. Muscles cannot convert ______ into urea.
Ammonia
During starvation or excessive activity, amino acids are broken down. What does alanine aminotransferase do at this point?
Transfers the amino group to pyruvate to make alanine, which is then released to the blood and then the liver to remove NH3 to make pyruvate.
Does cardiac muscle function aerobically or anaerobically?
Aerobically
Does cardiac have glycogen reserves?
No
What serves as the primary fuel for cardiac muscle?
Fatty acids
What is the preferred secondary fuel of cardiac muscle?
Ketone bodies
What else can serve as fuel for cardiac muscle?
Lactate
Explain at the most basic level what happens after fatty acid synthesis.
Fatty acids synthesized in the liver are converted to triacylglycerols,which are shipped to adipose tissue by VLDLs.
What activates extracellular lipases to cut off free fatty acids?
Insulin
Why is a steady supply of glucose required to generate glycerol-3P for TAG?
There’s no glycerol kinase in adipose.
When blood glucose concentrations are ______, glucagon activates ______.
…..low…..lipase…..
What carries free fatty acids to tissues?
Serum albumin
What is the primary role of the kidney?
To excrete water-soluble waste.
During prolonged starvation, kidney cortex cells may produce up to __% of blood glucose.
50
What maintains blood glucose concentrations?
The liver.
What regulates the concentrations of nearly all metabolites in the blood?
The liver.
How much of a supply of glucose does the liver maintain in the form of glycogen?
About 1 day’s worth.
What does the liver produce in the fed state?
Fatty acids for storage.
What does the liver produce in the starved state?
Ketone bodies
Glucokinase only pulls glucose into the liver for storage when glucose levels are what?
High
What does the liver lack that prevents it from using ketone bodies as fuel?
CoA transferase
Which body parts have urea cycle enzymes?
Liver & kidney
Which metabolites connect the many pathways?
Glucose 6-phosphate, pyruvate, acetyl CoA
What hormone is released from the adrenal gland during times of stress?
(Nor)epinephrine
Epinephrine binds receptors on what tissue and/or organs?
Muscle, adipose, liver
What does epinephrine do for liver, muscle, and adipose?
Liver - gluconeogenesis, glycogen phosphorylase, inactivates glycogen synthase to mobilize glucose.
Muscle - promotes glycolysis by raising fructose-2, 6-BP, which activates PFK.
Adipose - mobilizes fatty acids.
______ blood glucose concentration causes a release of ______ from alpha cells in pancreas islets of Langerhans.
Low…..glucagon…..
______ blood glucose concentration causes the release of ______ from beta cells of of pancreas islets of Langerhans.
High……insulin…..
Cortisol is a hormone that does what?
Indicates long-term stress, e.g. anxiety, fear, pain, infection, chronically low blood glucose concentration.
Where is cortisol produced and how does it act?
Produced by adrenal cortex - acts slowly by changing expression of metabolic enzyme genes.
What kind of amino acids give rise to precursors for glucose synthesis?
Glucogenic amino acids
Alpha-ketoglutarate, succinyl-Coa, fumarate, oxaloacetate, and pyruvate are made what kind of amino acids? What are they?
Glucogenic amino acids - precursors for glucose synthesis
What kind of amino acids give rise to ketone bodies and are degraded to acetyl-CoA or acetoacetate?
Ketogenic amino acids
The following are what kind of amino acids: Asp, Arg, Phe, Tyr, Ile, Met, Val, Gln, Glu, Pro, His, Ala, Ser, Cys, Gly, Thr, Trp?
Glucogenic
The following are what kind of amino acids: Leu, Lys, Phe, Tyr, Ile, Thr, Trp?
Ketogenic
Which amino acids can only be ketogenic?
Leucine & lycine
