Cell/molec Physiology

1. What are the steps involved in mitochondrial symbiosis?

1. Direct fusion of two prokaryotic cells 2. Transfer of genetic material between two prokaryotes 3. Formation of a eukaryotic cell without symbiosis

1. Infolding of plasma membrane
2. Engulfing of prokaryote (if heterotrophic then it creates heterotrophic ancestral eukaryote); (if phototrophic then it creates a photosynthetic ancestral eukaryote)

Mitochondrial symbiosis involves the infolding of the plasma membrane followed by the engulfing of a prokaryotic cell by a host cell.

Explanation

Mitochondrial symbiosis involves the infolding of the plasma membrane followed by the engulfing of a prokaryotic cell by a host cell.

2. What are the three steps for mitochondrial fission? Which two proteins are considered the most important?

1. Initiation of separation site 2. Formation of fusion protein complex (Drp-2 and hFis2) 3. Completion of fusion

1. Initiation of constriction site
2. Formation of constriction protein complex(Drp-1 and hFis1)
3. Completion of fission.

The two most important proteins are hFis1 and Drp-1 (dynamin related protein 1). All of which are GTPases.

1. Inhibition of constriction site 2. Disruption of fission protein complex (Mfn2 and Opa2) 3. Inhibition of fission

1. Activation of fusion protein complex 2. Formation of division protein complex (Mfn1 and Opa1) 3. Completion of synthesis

3. Mention the three steps for mitochondrial fusion. What 2 proteins are the most important?

3. Mitochondrial fusion is a spontaneous process and does not require specific proteins.

1. Mitochondrial fission prevents fusion of mitochondria.

2. Proteins involved in mitochondrial fusion include Ribosomal protein L5 and Nuclear receptor coactivator 7 (NCOA7).

1. Docking or tethering of Mfn1
2. Outer membrane fusion that requires a change in pH and GTP
3. Inner membrane fusion that requires a change in inner membrane potential and high GTP concentration.

The most important proteins are mitofusin 1 (Mfn1) and Optic Atrophy 1 (OPA1). All of which are GTPases.

Mitochondrial fusion is a complex process involving specific steps and proteins such as Mfn1 and OPA1. The incorrect answers provided do not align with the actual mechanisms involved in mitochondrial fusion.

Explanation

Mitochondrial fusion is a complex process involving specific steps and proteins such as Mfn1 and OPA1. The incorrect answers provided do not align with the actual mechanisms involved in mitochondrial fusion.

4. Why are mitochondria important for life?

They produce oxygen for cellular respiration.

They provide for ATP and heat. They are the powerhouses of the cell.

They regulate cell division and growth.

They store genetic information for the cell.

Mitochondria are known as the powerhouses of the cell because they produce ATP (adenosine triphosphate), which is the primary energy source for cellular functions. Additionally, mitochondria also play a role in heat generation within the cell.

Explanation

Mitochondria are known as the powerhouses of the cell because they produce ATP (adenosine triphosphate), which is the primary energy source for cellular functions. Additionally, mitochondria also play a role in heat generation within the cell.

5. Why does a human body produce a quantity of ATP that is more than 1000 times the quantity obtained when measuring total body ATP?

Due to a genetic mutation that increases ATP production in humans.

Because humans have more mitochondria compared to other organisms.

It is because ATP in a human body is recycled around 1200 times a day.

Because ATP cannot be stored and must be constantly regenerated.

The correct answer explains why a human body produces significantly more ATP than the total body quantity measured, highlighting the importance of ATP recycling in the body's energy production processes.

Explanation

The correct answer explains why a human body produces significantly more ATP than the total body quantity measured, highlighting the importance of ATP recycling in the body's energy production processes.

6. How many times is ATP recycled per day? How much ATP does a human consume per day? How much ATP would be in your body if I were to measure it?

500 times. A human consumes 10kg of ATP/day. Around 200g.

1200 times.
A human consumes 60kg of ATP/day.
Around 50g.

1500 times. A human consumes 70kg of ATP/day. Around 100g.

800 times. A human consumes 45kg of ATP/day. Around 25g.

The correct answer is 1200 times, where a human consumes 60kg of ATP/day and there would be around 50g of ATP in the body if measured.

Explanation

The correct answer is 1200 times, where a human consumes 60kg of ATP/day and there would be around 50g of ATP in the body if measured.

7. What are the main energy substrates for ATP synthesis?

Free Fatty Acids and Carbohydrates

Proteins and Nucleic Acids

Alcohol and Caffeine

Vitamins and Minerals

The correct answer includes Free Fatty Acids and Carbohydrates as they are commonly used by the body to produce ATP, the main energy currency of cells.

Explanation

The correct answer includes Free Fatty Acids and Carbohydrates as they are commonly used by the body to produce ATP, the main energy currency of cells.

8. Explain the process of FFA uptake by the cell for ATP production through FAO.

2. FAT (CD36) transports FFA into the nucleus for ATP synthesis. 2. FFA are directly converted into ATP without undergoing any transformation. 3. Fatty Acyl coA synthetase inhibits the uptake of FFA into the cell.

1. GLUT1 facilitates the entry of FFA into the cell. 2. FFA are converted to pyruvate before entering the mitochondria for ATP production. 3. CPT-1 and CPT-2 are involved in the transport of glucose into the cell.

1. FAT (CD36) allows for FFA to get thru the PM.
2. FFA get converted to Acyl-CoA by FACS (Fatty Acyl coA synthetase)
3. CPT-1 transfers acyl-CoA thru the OMM.
4. CPT-2 transfers acyl-CoA thru the IMM.
5. Once inside, the acyl-CoA undergoes b-oxidation to produce acetyl-CoA
6. Acetyl-CoA goes thru the TCA cycle-> ETC

3. FFA are taken up by the cell through endocytosis. 2. FFA are stored in the lysosomes for later use in ATP production. 3. The TCA cycle is bypassed in the metabolism of FFA for ATP generation.

The correct answers highlight the step-by-step process of FFA uptake and conversion to acetyl-CoA for ATP production through FAO. The incorrect answers provide misleading information or inaccurate steps in the process, emphasizing the importance of understanding the correct sequence of events in cellular metabolism.

Explanation

The correct answers highlight the step-by-step process of FFA uptake and conversion to acetyl-CoA for ATP production through FAO. The incorrect answers provide misleading information or inaccurate steps in the process, emphasizing the importance of understanding the correct sequence of events in cellular metabolism.

9. Explain how carbohydrates are uptaken by the cell to produce ATP. Glucose Oxidation.

2. Glucose is transported into the cell by passive diffusion.

1. Glucose is directly converted to ATP in the cell.

1. Glut1 (or Glut4 in presence of insulin) transports glucose into the cell thru the PM.
2. Glucose undergoes glycolysis in the cytosol which produces pyruvate.
3. Pyruvate freely transports itself into the IMM.
4. There, it gets converted to acetyl coA by pyruvate dehydrogenase.
5. Then TCA and ETC.

3. Glucose is broken down into fatty acids for ATP production.

Carbohydrates are not directly converted to ATP in the cell, they undergo a series of metabolic processes such as glycolysis, pyruvate conversion to acetyl coA, TCA cycle, and electron transport chain to produce ATP.

Explanation

Carbohydrates are not directly converted to ATP in the cell, they undergo a series of metabolic processes such as glycolysis, pyruvate conversion to acetyl coA, TCA cycle, and electron transport chain to produce ATP.

10. What are 5 ways glucose oxidation can be regulated?

1. Glucose-6-Phosphate promotes hexokinase activity. 2. Acetyl CoA activates pyruvate dehydrogenase. 3. Citrate promotes citrate synthase activity.

1. Glucose-6-Phosphate inhibits hexokinase.
2. Acetyl CoA inhibits pyruvate dehydrogenase.
3. Citrate inhibits citrate synthase
4. Succinyl CoA inhibits alpha ketoglutarate dehydrogenase.
5. ATP inhibits most steps in Glycolysis and TCA and ADP and AMP promote them.
Also ADP promotes the ETC

11. Explain the process of acyl-coA transportation across the mitochondrial membrane.

3. Acyl-CoA is transported across the mitochondrial membrane through glucose metabolism.

1. Acyl-CoA is directly transported across the mitochondrial membrane through passive diffusion.

1. FFA are conv to Acyl-CoA by FACS
2. CPT1 enters it while converting carnitine to acylcarnitine
3. Once in the mitochondrial matrix, 2 proteins allow its entrance to the IMM.
4. Carnitine Acylcarnitine Translocase enters an Acylcarnitine and takes out a Carnitine.
5. CPT2 takes that acetylcarnitine and converts it to acyl CoA and Carnitine (which is then taken out by CAT)

2. CPT1 converts acylcarnitine to carnitine for transportation across the mitochondrial membrane.

The process of acyl-coA transportation across the mitochondrial membrane involves a series of steps including conversion of FFA to Acyl-CoA, conversion of carnitine to acylcarnitine by CPT1, and the roles of proteins like Carnitine Acylcarnitine Translocase and CPT2 in facilitating the process. The incorrect answers provided do not accurately describe the mechanisms involved in this transportation process.

Explanation

The process of acyl-coA transportation across the mitochondrial membrane involves a series of steps including conversion of FFA to Acyl-CoA, conversion of carnitine to acylcarnitine by CPT1, and the roles of proteins like Carnitine Acylcarnitine Translocase and CPT2 in facilitating the process. The incorrect answers provided do not accurately describe the mechanisms involved in this transportation process.

12. Why is the malate-aspartate shuttle needed?

To break down fatty acids for energy

Because the IMM is impermeable to NADH

To regulate the citric acid cycle

To convert glucose into ATP efficiently

The malate-aspartate shuttle is needed because the inner mitochondrial membrane is impermeable to NADH, requiring the shuttle to transport reducing equivalents into the mitochondrial matrix for ATP production.

Explanation

The malate-aspartate shuttle is needed because the inner mitochondrial membrane is impermeable to NADH, requiring the shuttle to transport reducing equivalents into the mitochondrial matrix for ATP production.

13. Explain the malate-aspartate shuttle.

3. Glutamate is converted to Malate in the mitochondrial matrix as part of the malate-aspartate shuttle.

2. Oxaloacetate is directly transported into the cytosol for conversion to Asp in the malate-aspartate shuttle.

1. Glycolysis produces NADH
2. Meanwhile, Asp is carried to cytosol by glutamate-aspartate transporter
3. Aspartate aminotransferase converts Asp to Oxaloacetate and alphaketoglutarate to Glu.
4. Malate dehydrogenase converts Oxaloacetate to Malate by using NADH and a proton generated by glycolysis to give NAD.
5. The malate-alphaketoglutarate transporter transports the Malate into the mitochondrial matrix.
6. Once inside, the malate dehydrogenase converts Malate and a NAD into oxaloacetate and NADH.
7. Aspartate aminotransferase converts oxaloacetate into Asp. which is carried to cytosol by glutamate-aspartate transporter.

1. The malate-aspartate shuttle involves the production of ATP through mitochondrial respiration.

The malate-aspartate shuttle is a crucial process for transferring reducing equivalents between the cytosol and the mitochondria in cells. It does not involve ATP production, direct transport of Oxaloacetate into the cytosol, or the conversion of Glutamate to Malate in the mitochondrial matrix.

Explanation

The malate-aspartate shuttle is a crucial process for transferring reducing equivalents between the cytosol and the mitochondria in cells. It does not involve ATP production, direct transport of Oxaloacetate into the cytosol, or the conversion of Glutamate to Malate in the mitochondrial matrix.

14. Apart from the malate-aspartate shuttle, what other mechanism is used to shuttle NADH produced in glycolysis to the mitochondria? Describe it.

The glycerol-3-Phosphate shuttle.
1. The glycerol-3-phosphate from glycolysis donates two hydrogens to form FADH2 from FAD in Complex II. Furthermore, those electrons are transfered to QH2 which gives them to complex III.
2. Once this happens the G-3-P turns into Dihydroxyacetone phosphate.
3. The glycerol-3-phosphate dehydrogenase then takes the DHA and NADH plus a proton from glycolysis and turns them into G-3-P and NAD.

This synthesizes 1.5 ATP per pair of electrons while the Mal-Asp shuttle synthesize 2.5 ATP/pair.

The citrate shuttle

The oxaloacetate shuttle

The pyruvate shuttle

The correct answer is the glycerol-3-Phosphate shuttle. This mechanism involves the conversion of glycerol-3-phosphate from glycolysis to shuttle NADH to the mitochondria for ATP synthesis.

Explanation

The correct answer is the glycerol-3-Phosphate shuttle. This mechanism involves the conversion of glycerol-3-phosphate from glycolysis to shuttle NADH to the mitochondria for ATP synthesis.

15. Where do the Malate-aspartate shuttle and glycerol-3-Phosphate shuttle occur?

Malate-aspartate shuttle: Lung, Stomach; glycerol-3-Phosphate shuttle: Liver, Pancreas

Malate-aspartate shuttle : Liver, Kidney, Heart
and glycerol-3-Phosphate shuttle ocurrs: brain and skeletal muscle.

Malate-aspartate shuttle: Brain, Skeletal Muscle; glycerol-3-Phosphate shuttle: Kidney, Stomach

Malate-aspartate shuttle: Intestines, Skin; glycerol-3-Phosphate shuttle: Heart, Lungs

The Malate-aspartate shuttle primarily occurs in tissues with high energy demands like liver, kidney, and heart. On the other hand, the glycerol-3-Phosphate shuttle is found in brain and skeletal muscle, aiding in energy metabolism.

Explanation

The Malate-aspartate shuttle primarily occurs in tissues with high energy demands like liver, kidney, and heart. On the other hand, the glycerol-3-Phosphate shuttle is found in brain and skeletal muscle, aiding in energy metabolism.

16. How many protons are pumped by Complex I, III, IV?

4,2,4

2,4,2

2,3,2

4,4,2.

Complex I pumps 4 protons, Complex III pumps 4 protons, and Complex IV pumps 2 protons during the electron transport chain in cellular respiration.

Explanation

Complex I pumps 4 protons, Complex III pumps 4 protons, and Complex IV pumps 2 protons during the electron transport chain in cellular respiration.

17. Describe the path of the electrons through Complex IV.

Fe-S > cytochrome c > CuA > heme a

NADH > Fe-S > a > a3/CuB

Cyt b > CuB > c > c1/CuA

Cyt c > CuA>a>a3/CuB

Complex IV, also known as cytochrome c oxidase, is the final enzyme in the electron transport chain. The correct path of electrons through Complex IV involves the transfer of electrons from cytochrome c to CuA to a to a3/CuB.

Explanation

Complex IV, also known as cytochrome c oxidase, is the final enzyme in the electron transport chain. The correct path of electrons through Complex IV involves the transfer of electrons from cytochrome c to CuA to a to a3/CuB.

18. Which complex is the major generator of proton motive force? How much oxygen does it consume?

Complex II. It consumes 30% of our oxygen

Complex III. It consumes 70% of our oxygen

Complex I. It consumes 50% of our oxygen

Complex IV. It consumes 90% of our oxygen.

In the process of electron transport chain, Complex IV (cytochrome c oxidase) is the major generator of proton motive force and consumes 90% of the oxygen we breathe. This is an essential step in cellular respiration to produce ATP.

Explanation

In the process of electron transport chain, Complex IV (cytochrome c oxidase) is the major generator of proton motive force and consumes 90% of the oxygen we breathe. This is an essential step in cellular respiration to produce ATP.

19. Describe both adenine nucleotide and phosphate translocases.

1. ANT: antiporter: ADP inside por ATP outside.

ATP has 4- charge ADP 3- charge this alters delta psi using up one charge per ATP.
2. Phosphate translocase has phosphate 1- charge enter with a proton.
3. Ese fosfato se usa para fosforilar ADP a ATP usando el proton de la sintasa.
Finalmente un proton entra por ADP/ATP/Pi uptake. Si otros tres entraron x la subunidad Fo/Fi, 4 protones en total entran por cada ATP producido.

2. Phosphate translocase moves phosphate outside the mitochondria without involving a proton.

1. Adenine nucleotide translocase moves ATP outside and ADP inside with a net neutral charge.

3. ADP and ATP are exchanged between mitochondria and cytoplasm through a unidirectional transporter.

20. What are the two roles of ATP synthase?

ATP synthesis and ATP hydrolysis.

Lipid metabolism and carbohydrate digestion.

Cell respiration and photosynthesis.

Protein synthesis and DNA replication.

ATP synthase is an enzyme that plays a key role in the production of ATP through both synthesis and hydrolysis reactions.

Explanation

ATP synthase is an enzyme that plays a key role in the production of ATP through both synthesis and hydrolysis reactions.

21. Mention 5 agents that interfere with oxidative phosphorylation.

.

3. Caffeine

2. Penicillin

1. Aspirin

Agents like rotenone, cyanide, carbon monoxide, oligomycin, and antimycin A specifically target different components of the electron transport chain in oxidative phosphorylation, ultimately disrupting ATP production.

Explanation

Agents like rotenone, cyanide, carbon monoxide, oligomycin, and antimycin A specifically target different components of the electron transport chain in oxidative phosphorylation, ultimately disrupting ATP production.