Lecture 7: CSF Energy Flashcards
What is ATP?
Adenosine triphosphate is a molecule that acts as the energy currency in our body
How does ATP act as an energy source?
The hydrolysis of ATP to ADP and an inorganic phosphate group releases energy
What is the ATP cycle?
The transfer of energy between complex and simple molecules in the body
What happens to glucose in the body as it is consumed?
Glucose in intestines -> absorbed into bloodstream -> entry into cell (facilitated by insulin) -> used for cellular respiration or storage
What is cellular respiration?
The controlled release of energy from organic compounds to produce ATP
What are the 4 main steps of cellular respiration?
Glycolysis
Pyruvate oxidation (link reaction)
Citric acid cycle (or Krebs cycle)
Electron transport chain
What is the overall formula for cellular respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (in the form of ATP)
Where does glycolysis occur?
In the cytosol of the cell
Where does pyruvate oxidation occur?
In the matrix of mitochondria
Where does citric acid cycle occur?
In the matrix of mitochondria
Where does oxidative phosphorylation occur?
Across the inner membrane (involving intermembranal space and mitochondrial matrix)
What is the input and output of glycolysis?
Input:
1 Glucose
Output:
2 Net ATP (2 used and 4 produced)
2 NADH
2 Pyruvate molecules
Does glycolysis require oxygen?
No
What is NADH and FADH2?
Electron carriers that donate electrons for the electron transport chain
What is the input and output of pyruvate oxidation?
Input: 2 Pyruvate (per gluose)
Output:
2 Acetyl coA
2 NADH
2 CO2
Is oxygen required for pyruvate oxidation?
Yes
What is the input and output of citric acid cycle?
Input:
2 acetyl coA (per glucose)
Output: 2 ATP 6 NADH 2 FADH2 4 CO2
Does citric acid cycle require oxygen?
Yes, it is an aerobic process
What is substrate phosphorylation?
ATP generated by direct transfer (from a substrate) of phosphate group to ADP - occurs during glycolysis and citric acid cycle (low yield)
What is oxidative phosphorylation?
ATP generated from the oxidation of NADH and FADH2 and the transfer of electrons and pumping of protons. Much more efficient
Where is the electron transport chain?
Located on the inner membrane of mitochondria
What is the input and output of oxidative phosphorylation?
Input:
1 or 2 electrons depending on oxidation of NADH and FADH2 (from citric acid cycle)
Output:
26 to 28 ATP (per glucose molecule)
Does oxidative phosphorylation require oxygen?
Yes, oxygen is required to act as the final electron acceptor for the electrons of the ETC forming water
Explain how oxidative phosphorylation occurs
NADH and FADH2 are oxidised to donate 1 or 2 electrons
Electrons move along ETC from protein to protein
At each protein, electron gives up a small amount of its energy giving hydrogen pumps energy to actively transport H+ ions into the intermembranal matrix. As the H+ ions later diffuse down conc. gradient they pass through a ‘turbine’ known as ATP synthase which generates a large amount of ATP molecules.
Oxygen pulls the electron down the chain acting as the final electron acceptor where it is reduced to water.
What is chemiosmosis?
The diffusion of hydrogen ions through ATP synthase down their conc. gradient providing energy for ATP synthesis to occur.
What is phosphofructokinase?
A structure formed midway through glycolysis which acts as the rate limiting factor of glycolysis. It works by a negative feedback mechanism where the production of citrate and ATP molecules inhibit this enzyme stopping the formation of pyruvate
What is hyperglycemia?
High blood sugar level
What happens during hyperglycemia?
Homeostasis disturbed by increasing blood level -> Beta cells in islets of langerhans in pancreas secrete insulin -> increased rate of glucose transport to target cells, increased rate of glucose use and ATP generation, increased conversion of glucose to glycogen (storage molecule for sugar)
What is hypoglycemia?
Low blood sugar level
What happens during hypoglycemia?
Homeostasis disturbed by low sugar level -> alpha cells in pancreatic islets secrete glucago -> affects liver and skeletal muscle -> increased breakdown of glycogen to glucose
What is homeostasis?
The maintenance of relatively constant conditions within physiological tolerable limits
What is insulin?
Produced by beta cells of islets of langerhans in pancreas
It is a hormone which increases conversion of glucose to glycogen, increase glucose uptake by cells
What is glucagon?
Produced by alpha cells in islets of langerhans of pancreas
Hormone that increases breakdown of glycogen to glucose
What is diabetes mellitus?
The impairment of the ability to produce or respond to hormone insulin
Results in:
- elevated levels of glucose in blood as no glucose uptake by cells and no conversion of glucose to glycogen
- abnormal metabolism of carbohydrates
What is type 1 diabetes?
Also known as insulin dependent diabetes:
- Body produces no insulin as beta cells are destroyed due to autoimmune disease or genetic reasons
- Affects 5-10% of diabetics
- Requires insulin injections
What is type 2 diabetes??
Also know as non insulin dependent diabetes:
- Body does not respond to insulin
- Most diabetics are type 2
- Can be linked to obesity
- Cause unknown
What are the symptoms of diabetes mellitus?
Significantly increased hunger and significant loss of weight
