Lecture 7: Respiration Flashcards
What are the major fuel types?
Carbohydrates:
broken down to simple sugars
Proteins:
broken down to amino acids
Fats:
broken down to simple fats
Are all cellular processes spontanous?
No. Many cellular processes require energy.
For example, cilia beating
What is cellular energy?
ATP
Adenosine tri-phosphate
What does the ATP cycle describe?
The transfer of energy between complex and simple molecules in the body, with ATP as the mediator.
What is the simplest chemical equation of respiration?
C₆H₁₂O₆ + 6 O₂ –> 6 CO₂ + 6 H₂O + Energy
What are the steps of the conversion of glucose to ATP?
- Glycolysis
- Pyruvate oxidation (Link Step)
- Citric Acid Cycle (KERBS Cycle)
- Oxidative Phosphorylation
Where does Glycolysis occur?
Occurs in cytosol (Outside the mitochondria)
What functions require Oxygen?
Glycolysis - Oxygen Not Required
Pyruvate Oxidation - Oxygen Required
Citric Acid Cycle - Oxygen Required
Oxidative Phosphorylation - Oxygen Required
What is the Net Chemical result of Glycolysis?
Glucose –> 2 Pyruvate (Pyruvic Acid) + 2 H₂0
4 ATP Produced – 2 ATP used –> 2 ATP Net
2 NAD⁺ + 4 e⁻ + 4 H⁺ –> 2 NADH + 2 H⁺
How many carbons does Glucose have?
6 Carbon-base
How many carbons does Pyruvate (Pyruvic Acid) have?
3 Carbon-base
What are the phases of Glycolysis?
Energy Investment Phase
Energy Payoff Phase
What is the chemical equation of the Energy Investment Phase of Glycolysis?
2 ATP –> 2 ADP + 2 P
What is the chemical equation of the Energy Payoff Phase of Glycolysis?
4 ADP + 2 P –> 4 ATP
2 NAD⁺ + 4 e⁻ + 4 H⁺ –> 2 NADH + 2 H⁺
What is the chemical equation for Glucose in Glycolysis?
Glucose –> 2 Pyruvate (Pyruvic Acid) + 2 H₂0
C₆H₁₂O₆ –> C₃H₄O₃ + 2 H₂0
What does Pyruvate Oxidation (Link Step) do?
This step links glycolysis to the citric acid cycle
Turns the Pyruvate (3C) into Acetyl CoA (2C)
Acetyl CoA can enter the citric acid cycle, Pyruvate cannot
Where does Pyruvate Oxidation (Link Step) happen?
Occurs in the mitochondrial matrix
What are the products of the Pyruvate Oxidation (Link Step)?
No ATP,
1 NADH per pyruvate (or 2 per glucose) plus 1 CO₂
Where does the Citric Acid Cycle occur?
In the Mitochondria Matrix
What are the products of the Citric Acid Cycle?
Results in:
2 ATP
6 NADH
2 FADH₂
4 CO₂
(per glucose molecule)
Does the Citric Acid Cycle require Oxygen?
Requires oxygen – it is an aerobic process
What are NADH and FADH₂?
FADH₂ and NADH are electron donors in the electron transport chain
What level of extraction is there after the Citric Acid Cycle?
The citric acid cycle completes the extraction of energy from glucose
No more carbon bonds to be broken
What makes up Oxidative Phosphorylation?
Electron Transport Chain + Chemiosmosis
What types of reactions are…?
1. Glycolysis
2. Citric Acid Cycle (KERBS Cycle)
Substrate phosphorylation (Direct Transfer):
ATP generated by direct transfer (from a substrate) of a phosphate group to ADP
Glycolysis and Citric acid cycle make ATP via substrate phosphorylation
What is the definition of Oxidative Phosphorylation?
Oxidative phosphorylation (Free Phosphates):
ATP is generated from the oxidation of NADH and FADH₂ and the subsequent transfer of electrons and pumping of protons
Bulk of ATP production happens here
What does Cyanide do?
Cyanide blocks passage of electrons to O₂ at complex 4. Resulting in the death of the cell.
Where does the Election Transport Chain occur?
Occurs at proteins at the inner membrane
Does the Electron Transport Chain require Oxygen?
Requires Oxygen – Aerobic process
Oxygen “pulls” the electrons down the chain, and is then the final electron acceptor where it is reduced to water
2 H⁺ + ½ O2 –> H₂O)
What are used in the Electron Transport Chain?
NADH and FADH₂ from Glycolysis and the Citric acid cycle are used here
What are the helper proteins for the Electron Transport Chain?
Q and Cyt c are helper proteins.
What are the Protein Complexes involved in the Electron Transport Chain?
Requires Complex 1, 2 (peripheral), 3, 4
All are hydrogen pumps
What Protein Complexes accept which electron donors?
NADH –> Complex 1 + NAD⁺
FADH₂ –> Complex 2 + FAD
What is the function of Chemiosmosis?
(Waterfall)
High concentration of Hydrogens drive down through ATP Synthase, tumbling through to create ATP from ADP + P
The rotation of the ATP synthase turbine enables the phosphorylation of ADP to generate ATP
How much ATP does Chemiosmosis produce?
26 ~ 28 ATP per glucose!
What is the ‘gate-keeper’ for Glycolysis?
Phosphofructokinase
It catalyzes step 3 – where glycolysis becomes irreversible
What is the ‘gate-keeper’ of Glycolysis inhibited by?
inhibited by citrate and ATP
ie. products of cellular respiration
What is the ‘gate-keeper’ of Glycolysis stimulated by?
stimulated by AMP
AMP accumulates when ATP is being used rapidly
What is the definition of Homeostasis?
The maintenance of relatively constant conditions within physiologically tolerable limits
What is Insulin produced by?
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 storage in liver)
What is Glucagon produced by?
Produced by alpha cells of Islets of Langerhans in pancreas
What is the function of Glucagon?
Stimulates the breakdown of glycogen (Cross-linked glucose in liver/skeletal muscle) to increase blood sugar levels
What happens if 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 is Type 1 or insulin-dependent diabetes?
Body does not produce insulin, as beta cells of pancreas are destroyed, often this is autoimmune, or genetic or through environmental factors
Affects 5 – 10 % of diabetics, and onset usually occurs in children or adolescents.
Requires insulin replacement
What is Type 2 or non-insulin-dependent diabetes?
Body produces insulin, but receptors are non functional (insulin resistance)
Most (>90%) diabetics are Type II, usually adults over the age of 40
Can be linked to other pathologies and obesity
What are the steps of Diabetes mellitus as caused by a lack of functional insulin?
As a result, levels of glucose in the blood build up, well beyond normal
homeostatic limits.
Increased blood glucose alters the volume and osmolarity of blood, with
subsequent pathological consequences.
What are the symptoms of Diabetes mellitus as caused by a lack of functional insulin?
Significantly increased hunger
Significant weight loss
What is the mmol/L levels for fasting?
≥7mmol/L
What is it called when Homeostasis is disturbed by increasing glucose levels?
Hyperglycemia
What is it called when Homeostasis is disturbed by decreasing glucose levels?
Hypoglycemia
What is the receptor for decreasing glucose levels?
Alpha Cells in Pancreatic Islets –> Secrete glucagon
What are the effectors for decreasing glucose levels?
Liver, Skeletal Muscle, Adipose Tissue
What is it called when Homeostasis is disturbed by increasing glucose levels?
Hyperglycemia
What is the receptor for increasing glucose levels?
Beta Cells in Pancreatic Islets –> Secrete Insulin
What are the effectors for increasing glucose levels?
All body cells
What do the effectors for increasing glucose 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
Increased amino acid absorption and protein synthesis
Increased triglyceride (fat) synthesis in adipose tissue
What do the effectors for decreasing glucose levels respond with?
Increased breakdown of glycogen to glucose (in liver, skeletal muscle)
Increased breakdown of fat to fatty acids (in adipose tissue)
Increased synthesis and release of glycose (in liver)
