Cellular Respiration Flashcards
Explain the process of glycolysis
What is the chemical equation for glycolysis?
Where does it take place?
What happens if there is a defect somewhere?
Glycolysis is the process of turning 1 glucose into 2 pyruvates. This happens without oxygen.
Equation : Glucose + 2NAD+ +2ADP + 2 Pi –> 2 Pyruvates + 2 NADH
This takes place in the cytoplasm of the mitochondria.
If there is a defect in hexokinase (the enzyme that turns glucose into glucose 6 phosphate), glycolysis would be less efficient. There would be a lower amount of glucose that gets converted to glucose 4 phosphate meaning there would be less pyruvates made and less ATP and NADH produced. This means less pyruvates enter Krebs so there is less FADH2 and NADH and ATP made. This would lead to a smaller gradient of protons going from the matrix to the intermembrane meaning less ATP is produced in the ATP synthase. Hence, less energy is made. Usually, a defect in hexokinase will lead to the lower enzyme activity level while rarely can inhibit the conversion of glucose to glucose 6 phosphate all together.
- Less ATP, however, means things like Red Blood cells are impacted because their ion channels need ATP and can start malfunctioning (losing its structure).
- Glucose can also be left in the bloodstream which can be potentially dangerous.
What is the structure of the mitochondria and where do all these processes take place? What is the function of mitochondria?
Glycolysis and the linked reaction take place in the cytoplasm of the cell which is usually a liver cell. Anaerobic respiration also happens there too (lactic acid and alcohol fermentation). Acetyl CoA enters into the mitochondria (an organelle fo the liver cell) and that is where the Krebs cycle, electron transport chain, and chemiosmosis take place.
Mitochondria
What is cellular respiration? What is the chemical equation for cellular respiration?
Cellular respiration is the process of releasing energy (ATP) by breaking down glucose and other food molecules in the presence of oxygen.
Equation: 6O2 + C6H12O6 –> 6CO2 + 6H2O + Energy
oxygen + glucose –> carbon dioxide + water + energy
What organisms have mitochondria?
Animal and plant cells.
What is a calorie? How much calories does one gram of sugar glucose release?
One gram of the sugar glucose (C6H12O6) when burned in the presence of oxygen, releases 3811 calories of heat energy.
A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.
What is oxidative phosphorylation?
What is substrate level phosphorylation?
What are some similarities and differences between the two?
Oxidative phosphorylation : this process starts from when the electron carriers from Krebs (NADH and FADH2) get oxidized into NAD + hydrogen + 2 electrons and ends when the final acceptor (oxygen) takes those electrons to form hydrogen. The process includes the intermediate steps of the electron transport chain and chemiosmosis. There needs to be these intermediate steps of cellular respiration so that as much energy can be reserved as possible and not lost to heat.
Substrate level phosphorylation : This occurs in glycolysis and Krebs and it is when
Similarities: ATP is produced
Why can bacteria in soil survive without oxygen?
These bacteria can survive without oxygen becuase they utilize anaerobic respiration which doesn’t need oxygen to complete the process. This generates enough energy (ATP) for the bacteria to sustain cellular processes.
What happens during a heart attack?
Blood flow to heart slows which limits the supply of oxygen to that region. This means cells switch to aerobic respiration in order to produce ATP. However, for complex organisms that rely on the production of more ATPs from cellular respiration, relying on lactic acid fermentation and anaerobic respiration for energy would not be sufficient to sustain cellular processes and can lead to cell death. Not only this, but the lactic acid produced would cause a buildup of it in the body which can turn the environment more acidic leading to the disruption of enzymatic activities, impaired cellular processes, and even cell death if it persists.
What type of respiration do red blood cells rely on?
RBC don’t have mitochondria so they rely on lactic acid fermentation (anaerobic respiration). The buildup of lactic acid is at a low and steady rate which makes it possible for the liver to process it maintaining the pH of the environement.
How is lactic acid fermentation useful for ATP production?
After glycolysis, you end up with the byproducts of 2 pyruvates, 2NADH, and 2 ATPs. In order to start glycolysis again and generate more ATPs, the NADH which was the byproduct of glycolysis needs to be transformed to NAD. Hence, by converting the pyruvates to lactic acid, NADH is oxidized back into NAD allowing for glycolysis to start all over again.
What type of respiration is used when doing hard exercise?
Lactic acid fermentation is used in muscle cells because there is a limited supply of oxygen. This is unsustainable because too little ATP is being produced to support all cellular processes. But also, the lactic acid buildup will lead to fatigue and pain in muscles and also an acidic environment in the body.
What is the process of the link reaction? Where does it happen?
This happens in the matrix of the mitochondria. This is where one pyruvate at the time gets decarboxylated meaning it releases a carbon molecule as CO2. This also oxidizes the pyruvate and reduces NAD+ to NADH. Then coenzyme A attatches itself to the 2 carbon molecule. There are two pyruvates so this reaction happens twice hence the byproducts of the link reaction are 2 acetyl CoA molecules, 2 CO2 molecules, and 2 NADH molecules.
How do the two phosphate groups at the first few steps of glycolysis make glucose unstable?
To get from glucose to glucose 6 phosphate, glucose gets phosphorylated so a loan of one ATP molecule turns into ADP. That phosphate group goes to the 6th carbon of the glucose molecule. This phosphorylation is done by hexokinase. Then, after the molecule gets rearranged, Fructose 6 phosphate gets phosphorylated into Fructose 1-6 bisphosphate. That phosphate group comes from another loan ATP molecule.
These two phosphate groups on the ends of the molecule make the molecule unstable because glucose is a neutral molecule and so that means it can pass through the membranes. With the two negative phosphates, it makes the molecule not able to pass through membrane so that glycolysis can happen. It also makes glucose more reactive so it can be split later into two 3-carbon molecules.
What happens if there is a defect in hexokinase?
Hexokinase is the enzyme that turns glucose into glucose 6 phosphate. A defect in hexokinase would typically cause a decrease in the enzyme activity and slow down glycolysis and makes the process less efficient. This means that less glucose molecules will be turned into glucose 6 phosphate so less pyruvates are made and there would be less ATP and NADH produced in cellular respiration (this includes in oxidative phosphorylation and Krebs cycle). In rare occasions, a defect in hexokinase can lead to its inability to turn glucose to glucose 6 phosphate which would stop cellular respiration as a while. Either way, less glucose would be converted to glucose 6 phosphate meaning less glucose is used. This is bad because there will be a buildup of glucose in the bloodstream.
Why is breathing and cellular respiration different?
Breathing is the intake of oxygen and release of carbon dioxide through and from the lungs. Breathing supplies the body with oxygen.
Cellular Respiration is the controlled release of energy from inorganic molecules to make ATP. This happens in the mitochondria.
