Energy Metabolism Flashcards
What provides energy and components required for anabolism?
Catabolism
Define anabolism.
the making of large, complex molecules from smaller, simpler molecules with the usage of stored energy.
Define catabolism.
the release of energy through the breakdown of large, complex molecules into simpler molecules.
Gluconeogenesis is the formation of new glucose molecules from non- carbohydrate carbon substrates. What 4 molecules can be used to synthesize new glucose molecules through this process?
- pyruvate (Kreb’s cycle)
- Lactate (Anaerobic glycolysis from muscle + RBC’s via Cori cycle)
- Glycerol (via lipolysis)
- Amino Acids (alanine and glutamine)
When and where does the process of gluconeogenesis take place?
In the liver, during times of fasting, starvation, and low carbohydrate diets.
Also occurs in the kidney.
Define glycolysis and it’s products.
Where one molecule of glucose is broken down for energy into 2 molecules of pyruvate, 4 ATP, 2NADH, 2 H+, and s H2).
Define Phosphorylation.
The process where a phosphate group is attached to a molecule or ion.
How does ATP provide energy for cellular processes?
Through the transfer of one of it’s phosphate groups to another molecule.
What is NADH used for?
Oxidative phosphorylation and ATP generation in the mitochondria
What metabolic process utilises pyruvate?
gluconeogensis.
What is the primary carbohydrate stored in the liver and muscle cells?
Glycogen
Define glycogenolysis.
- process by which glycogen is broken down into glucose to provide immediate energy and to maintain blood glucose levels during fasting or starvation
Where does the process of glycogenlysis take place?
hepatocytes
What molecules initiate the process of glycogenolysis?
Glucagon and epinephrine
What 3 enzymes are involved in the process of glycogenolysis?
- Glycogen phosphorylase, phosphoglucomutase, glucose-6-phosphatase
Define lipolysis and describe the products of this process.
Lipolysis is a cellular process that breaks down fats (or hydrolyses) (triglycerides) into free fatty acids and glycerol molecules
What enzymes drive the process of lipolysis?
And where does this take place?
lipase enzymes
in adipocytes and hepatocytes
Define lipogenesis.
Lipogenesis is the process of synthesizing fatty acids and triglycerides from nonlipid precursor molecules
Where does lipogenesis take place?
liver and adipose tissue
What compound is required to make palmitic acid, cholesterol and other fatty acids?
Acetyl CoA
What are the products at the end of lipogenesis?
diacylglycerides and triacylglycerides
What inhibits the process of lipogenesis? (x4)
Polyunsaturated Fatty acids
GH
Leptin
Fasting/starvation
What stimulates lipogenesis? (x2)
Carbohydrate rich diets and insulin
Why do glucose molecules require transporters?
they are both large and polar molecules
What is the key source of energy for most living cells?
Glucose
What are the 2 main types of glucose transporters?
- sodium–glucose linked transporters (SGLTs)
- facilitated diffusion glucose transporters (GLUTs)
GLUT’s have x3 classifications of transporters. Class 1 includes which transporters?
GLUT1-4
GLUT ? is expressed mainly in beta cells of the pancreas, liver and kidney.
2
GLUT ? is mainly present in the brain.
3
GLUT ? is an insulin-responsive glucose transporter that is found in the heart, skeletal muscle, adipose tissue, and brain
4
Which GLUT’s are in GLUT class II?
GLUT 5,7,9,11
GLUT ? has a high affinity for both glucose and fructose and is located in cells of the small intestine, colon, testis and prostate
7
GLUT ? (multiple isoforms) is expressed mainly in the proximal tubule of the kidney and in the liver and placenta
9
GLUT ? (three isoforms of GLUT11), A present in heart, skeletal muscle and kidney cells, GLUT11B present in placenta, adipose tissue and kidney cells and GLUT11C present in adipose tissue, heart, skeletal muscle and pancreas cells
11
What are the 5 subtypes of GLUT transporters in class III?
6,8,10,12,13
GLUT ?-brain and spleen cells and in peripheral leukocytes. It is a low-affinity glucose transporter that is located intracellularly
6
GLUT ? is a high-affinity transporter of glucose but inhibited by fructose and galactose. It is mainly distributed brain and testis cells
8
GLUT ? is located in cells of various tissues - skeletal muscle, heart, lung, brain, placenta, kidney, liver and pancreas
10
GLUT ? is expressed in cells of adipose tissue, small intestine, skeletal muscle and placenta
12
GLUT ? is expressed in adipose tissue and kidney cells; predominantly expressed in the brain. It is mainly located intracellularly vi PKC avtivation in neuronal cells.
13
What transporters symport (transport in the same direction) glucose in conjunction with sodium ions.
Sodium–glucose linked transporters
Which transporters require ATP?
GLUTs
Which transporters do not directly utilise ATP but function because other mechanisms have utilised ATP?
SGLT’s
What is required for SGLT’s to be able to transport glucose into the cell?
Sodium gradient created by the sodium-potassium ATPASE pumps.
Where are SGLT’s located?
SGLTs are present on the luminal surfaces of cells lining the small intestine and renal tubules where they absorb glucose from dietary sources and facilitate the re-absorption of glucose from the glomerular filtrate
SGLT’;s have 6 subtypes. Describe where they are located and discuss their function based on their locations.
What is the polypeptide that inhibits the activity of certain pancreatic and gastrointestinal hormones?
Somatostatin.
Somatostatin is produced by which endocrine pancreatic cells?
Delta
What is the main role of pancreatic somatostatin secretion?
To regulate rates of usage and storage of glucose, amino acids and fatty acids.
Which cells secrete pancreatic polypeptide?
F cells
What stimulates the secretion of pancreatic polypeptide?
eating, exercising, fasting
What does pancreatic polypeptide inhibit?
- gallbladder contraction
- pancreatic exocrine secretion
