Harvesting chemical energy Flashcards
What happens to ATP in mitochondria?
In mitochondria, ATP is hydrolyzed into ADP and an inorganic phosphate molecule
In summary, how is energy gained for bodily processes?
Cellular respiration is used to generate ATP which in turn provides energy for cellular processes via the transition between substrate ATP and product ADP
What is the ATP cycle?
The ATP cycle is the transfer of energy between complex molecules and simple molecules, using ATP
What are catabolic reactions
Catabolic reactions transfer energy from complex molecules to ATP - breakdown of complex molecules to simple molecules
What kind of reaction is cellular respiration?
A catabolic reaction
What are examples of the complex molecules that anabolic reactions transfer energy of ATP to
Glycogen, proteins, and tryglycerides
What are examples of simple molecules that form catabolic reactions transfer energy from complex molcules to ATP
Simple molecules such as glucose, amino acids, glycerol and fatty acids
What are anabolic reactions
Anabolic reactions transfer energy from ATP to complex molecules - addition of many simple molecules to form complex molecules
What are the three main sources of fuel in the body
The three main sources of fuel are carbohydrates (absorbed as simple sugars), proteins (absorbed as amino acids), and fats (absorbed as simple fats)
What are carbohydrates broken down and absorbed as
Simple sugars
What are proteins broken down and absorbed as
Amino acids
What are fats broken down and absorbed as
Simple fats
Main steps of fuel transferred to ATP energy
- organic molecules in food
- digestion and absorption (heat loss)
- nutrient molecules in body cells (energy lost in nitrogenous waste)
- cellular respiration (heat loss)
- ATP
What are the two ways that glucose can be used in the body
- Cellular respiration -> cellular work
- Storage for harder times -> glucose cross linked together, called glycogen, in liver and skeletal muscle
When glucose in bloodstream goes into the cell, what hormone is it facilitated by
Insulin
When storage of harder times goes back to glucose in bloodstream step, what hormone is ti facilitated by
Glucagon
What ar the 4 main steps of the conversion of glucose to ATP
- Glycolysis
- Pyruvate oxidation
- Citric acid cycle
- Electron transport chain
Where does glycolysis occur
In the cytosol
Is oxygen required in glycolysis
No
What reactants are required in glycolysis?
Glucose, 2 ATP, 2 NAD+
What products are formed in glycolysis?
2 pyruvate, 4 ATP, 2 NADH
What net ATP is produced in glycolysis?
Net of 2 ATP
What is pyruvate oxidation and what does it produce
Links glycolysis to the citric acid and forms Acetyl CoA
Where does pyruvate oxidation occur
Mitochondrion
How many ATP does pyruvate oxidation produce?
0 ATP
What are the products of pyruvate oxidation?
PER GLUCOSE MOLECULE:
(Acetyl-CoA, carbon dioxide, NADH) x2
What is the function of the Acetyl CoA produced in pyruvate oxidation
Enables the 2-carbon acetyl group to enter the citric acid cycle
Reactants and products in pyruvate oxidation
Pyruvate + O2 –> (Acetyl-CoA, carbon dioxide, NADH) x2
Where does the citric acid cycle occur
In the mitochondrial matrix
What is the citric cycle
Acetyl-CoA enters the cycle, forming citric acid with oxaloacetic acid, and then a series of reactions occurs in which the product of one reaction is the substrate for the next
What products does the citric acid result in:
Per glucose molecule:
* 2 ATP
* 6NADH
* 2FADH2
* 4 CO2
FADH2 and NADH are ____ in the electron transport chain
Electron donors
What are the reactants of citric cycle
Oxaloacetic acid
The citric cycle completes the extraction of _______
Energy from glucose
How much ATP does the citric cycle produce
2 ATP per glucose
What is substrate phosphorylation
ATP generated by direct transfer (from a substrate) of a phosphate group to ADP
What is oxidative phosphorylation
ATP is generated from the oxidation of NADH and FADH2, and the subsequent transfer of electrons and pumping of proteins
__ and __ make ATP via substrate phosphorylation
Glycolysis and citric acid cycle
Where does electron transport chain occur
At proteins within the inner membrane
What happens in the electron transport chain
- NADH and FADH2 oxidised to donate electrons
- e- transfer from protein-to-protein along chain through redox reactions
- at each transfer, each e- gives up small amount of energy enabling H+ pumped into intermembrane space
- O2 pulls e-down the chain, and is then the final electron acceptor where it is reduced to water
__ and __ from glycolysis and the citric cycle are used in electron transport chain
NADH and FADH2
What is chemiosmosis
A concentration gradient in which hydrogen ions in the intermembrane space rush down through ATP synthase.
This causes ‘turbine’ within ATP synthase to turn and enables phosphorylation of ADP to generate ATP
How much glucose is produced at the end of chemiosmosis
26 or 28 ATP per glucose
Is substrate or oxidation phosphorylation more efficient
Oxidation
What does the fall of electrons down the chain enable in oxidative phosphorylation
Enables movement of H+ ions into the intermembrane space and generates a proton gradient which “drives” the ATP synthase turbine
How is cellular respiration versatile
- can derive energy from that one glucose
- fats, proteins and more complex carbohydrates also generate ATP
- monomers enter glycolysis and the citric acid cycle at different points
What substance is rate limiting for glycolysis
Phosphofructokinase
How is the rate of cellular respiration regulated
It is regulated via a negative feedback loop, in which the end product inhibits earlier reactions
When is AMP stimulated
When ATP is being used too rapidly
What is insulin produced by
Beta cells of Islets of Langerhans in pancreas
What is the function of insulin
Promote glucose uptake into cells (for ATP production or liver storage)
What is glucagon produced by
Alpha cells in the Islets of Langerhans in pancreas
What is the function of glucagon
Stimulates the breakdown of glycogen to increase blood sugar levels
Insulin is secreted when blood sugar level is (__) and glucagon is secreted when the blood sugar level is (__).
Increasing and decreasing
How does the body respond when homeostasis is disturbed with increasing blood sugar levels
Respond with:
* increased rate of glucose transport into target cells
* increased rate of glucose use and ATP generation
* increased conversion of glucose to glycogen.
Where are the effectors located when there is decreasing blood glucose level
Liver, skeletal muscle and adipose cells
Where are the effectors located where there is increasing blood glucose level
All body cells
How do the effectors respond when there is a decreasing blood glucose level
- increased breakdown of glycogen to glucose (in the liver and skeletal muscle)
Hyperglycemia is when there is ___ blood glucose level, and hypoglycemia is when there is a ___ blood glucose level
Increasing and decreasing
What is the fasting blood glucose level?
around 4-6 mmol L-1
What happens when you lose the function of insulin
- No glucose in cells
- No ATP from glucose
- No glycogen stored for harder times
What is diabetes mellitus
- The ability to produce or respond to the hormone insulin is impaired.
- Results in abnormal metabolism of carbohydrates and elevated levels of glucose in the blood
What happens in type 1 diabetes
Body does not produce insulin, as beta cells of pancrease are destroyed. Requires insulin replacement
What is type 2 diabetes
Body produces insulin, but receptors are non functional (insulin resistance). Can be linked to other pathologies and obesity
What percentage of diabetics are type 1 and type 2
5-10% of diabetics are type 1, and most (>90%) are type2
What is diabetes mellitus caused by
Lack of functional insulin
What happens in diabetes mellitus that leads to its consequences
- Levels of glucose in blood increase due to lack of functional insulin.
- Increase blood glucose alters the volume and osmolarity of blood, with subsequent pathological consequences.
What are the two symtoms of diabetes mellitus
Significant increased hunger and weight loss
Glycolysis and Citric Acid cycle make ATP via ___
Substrate phosphorylation
