Metabolism Lectures 1 and 2 Flashcards
What is the common “product” and fuel of metabolism?
Acetyl Co A
- all metabolic components give rise to acetyl-coA
- to be used in CAC (Citric Acid cycle) for energy generation
- CAC is a combustion reaction and produces ATP, H20 and CO2
How are fatty acids stored?
What are they converted to after beta oxidation? Only cells with what?
- stored as triacylglycerol
2. Acetyl coA, only cells with mitochondria
Amino Acids:
- Storage
- Catabolism into what?
- what byproduct is made?
- Storage - Proteins
- Catabolism into what? –> Acetyl Co A
- what byproduct is made? Ammonia
What are the preference of energy for the following:
- Liver
- Adipose tissue
- Skeletal Muscle (rest & exertion)
- Heart
- Brain (fed, starved)
- Liver - fatty acids, glucose, AA’s
- Adipose tissue - fatty acids
- Skeletal Muscle
rest - fatty acids
exertion - glucose - Heart - fatty acids
- Brain (fed, starved)
fed: glucose
starved: ketone bodies/glucose
What is the driving force for the coordination of metabolism?
Provide glucose for the brain
Calculate the following:
500 kcal/day, of which 10 g of dry protein, what is the percent in total calories?
10g * 4 g (chart) = 40 kcal
40kcal/500 kcal/day * 100 = 8%
What is the source of the following carbs and state the enzyme that digests them:
- Amylose
- Sucrose
- Lactose
- Fructose
- Glucose
- Amylose
- potatoes, rice, corn, bread
Enzyme: Maltase - Sucrose
- table sugar, deserts
E: Sucrase - Lactose
- milk & products
E: Lactase - Fructose
- fruit, honey
E: - Glucose
- fruit, honey, grapes
What type of starch linkages does pancreatic amylase break down?
alpha 1,4 linkages
What is the main cause of lactose intolerance?
What expresses the LCT gene?
How is his different from milk allergy?
Deficiency in Lactase Enzyme production which breaks down lactose due to environmental factors, decline due to aging, damage to mucosa
Lactose is not sufficiently hydrolyzed/absorbed and remains in intestine
- causes the osmosis of water into the intestine
- intestinal bacteria (colonic) metabolize the lactose to lactic acid and mixtures of hydrogen, carbon dioxide, and methane gas
- result is bloating, flatulence, and diarrhea
2. LCT gene is expressed by intestinal epithelial cels and produces the lactase enzyme
3. Milk allergy is due to allergic reaction to alpha-S1 casein
(secondary lactose intolerance can be found in children with gastroenteritis = damage to intestinal lining)
What cells secrete insulin and glucagon? Under what conditions?
- insulin = beta cells of pancreas
- when glucose is high - Glucagon = alpha cells of pancreas
- when glucose is low
What is glycogenesis?
GLycolysis?
Gluconeogenesis?
Glycogenesis?
- Breakdown of glycogen to glucose 1 - phosphate and glucose in the liver and muscles by Glycogen phosphorylase
- Single glucose makes net 2 ATP, 2 NADH, and 2 H20
- generation of glucose from non-carb substrates (pyruvate or lactate)
- occurs in hypoglycemia (glucagon increases) - Formation of glycogen from glucose (hyperglycemia - insulin increases)
What is the level of glucose that causes hypoglycemia? What is the result
What about for HYPERGLYCEMIA?
Which leads to Type 2 Diabetes Mellitus?
- 60 mg/dL
- neurological issues, coma, death - 110 mg/dL
- lead to Type 2 Diabetes Mellitus
What carbohydrate metabolic pathway do RBC’s rely on?
Glycolysis since no mitochondria
What are the 2 types of glucose transportation?
- Facilitated Diffusion
- Secondary Active Transport via Na - Glu - Transport
- using energy gradient of Na
State the km, affinity, and max for the following:
- GLUT 1, 3, an 4
- GLUT 2
- GLUT 1, 3, an 4
- LOW km
- low max
- high affinity! - GLUT 2
- high km
- high max
- LOW AFFINITY
* * two sided**
State the following for GLUT 2 and GLUT 4
- Insulin dependent/independent
- Where are they found?
- bidirectional?
- High or low concentrations of glucose
GLUT 2:
- Insulin Independent
- low affinity for glucose - Liver, pancreatic beta cells, kidney, small intestine
- BIDIRECTIONAL
- sees HIGH concentrations of glucose
GLUT 4:
1. Insulin DEPENDENT
(affected in Type 2 Diabetes Mellitus)
2. Heart, Skeletal Muscle, Adipocytes!!!!
3. not bidirectional
4. HIGH affinity for glucose and sees LOW CONCENTRATIONS
What are the 3 important steps of glycolysis?
- Priming stage (ATP INVESTMENT)
- conversion of glucose to G-6-P (cannot reverse after this) - Splitting Stage
(aldolase A splits F-2,6,-BP to DHAP and Gly-A-3-P) - Oxidoreduction -phosphorylation stage (ATP EARNINGS)
- Where does glycolysis occur? Which cells?
- What is the end result
- When is glucose trapped in the cells ? (which step)
- What mediates the most highly regulated part of glycolysis?
- Cytoplasm, all cells
- 4 atp (2 Net ATP), 2 NADH, 2 H20
- when Glucose is converted to G-6-P (phosphorylated)
- Aldolase A (splitting step)
What enzyme deficiency causes hemolytic anemia?
- Pyruvate Kinase
- folded improperly
- cannot bind well to Pyruvate Enolase Phosphate (PEP)
- thus small amount of ATP is made from glucose
- the ATP cannot be used for Na-K ATPase pump
- Na accumulates in the cell
- cell is abnormally strutted and gets stuck in capillaries
- macrophages lyse these cells
- premature death
What are the 3 key enzymes in glycolysis?
- Hexokinase/Glucokinase
- PFK-1
- Pyruvate Kinase
When does substrate level phosphorylation occur?
When Gly-3- P is converted to 1,3, BPG
What are the 3 types of regulation of enzyme activity?
- Allosteric regulation
- Covalent Modification
(phosphorylation, de phosphorylation) - Induction/Repression of Enzyme synthesis (via Insulin and Glucagon)
Hexokinase:
- Present in which cells?
- What ALLOSTERICALLY inhibits it?
- Is it made at a constant amount?
- What is the km (low or high) for glucose? (saturated at low or high levels)
- Handles high or low levels of glucose?
- ALL cells
- allosterically inhibited by its product G- 6 - P
- CONSTANT, non-inducible, constitutive
- LOW km (saturated at low levels of glucose)
- handles low levels
Glucokinase:
- Present in which tissue cells? (WHERE in cell)
- what decreases its activity by translating it back to the nucleus?
What increases its activity?
- Is it made at a constant amount? (inducible or not? hormone?)
- What is the km (low or high) for glucose? (saturated at low or high levels)
- Handles high or low levels of glucose?
- Pancreas and liver
- in nucleus of cell - F - 6 - P
GLUCOSE allows it to leave the nucleus
- INDUCIBLE by insulin
- HIGH km for glucose
(not saturated at normal physiologic conditions)
- handles HIGH levels of glucose in the liver