Cellular Respiration Flashcards
Metabolism (30 cards)
What is cellular respiration?
It is the process by which organic molecules, taken in as food, are broken down in the cells to release energy for the cell’s activities
Provide examples of cell activities
Movement of the cell, uptake of materials, production and secretion of new chemical compounds
What is the purpose of cellular respiration?
The process occurs in every cell in the body, to supply each cell with the energy it needs in the form of ATP and heat
Where does cellular respiration occur?
Cytosol and Mitochondria
Why does the first stage of cellular respiration take place in the cytosol?
The enzymes required for anaerobic respiration are available in the cytosol of the cell
What processes occur in the cytosol?
Glycolysis and the conversion of pyruvate to lactic acid
Where does aerobic respiration occur?
Aerobic respiration occurs in the mitochondria of the cell
What are mitochondria?
Organelles constructed with a double membrane – an outer membrane that forms the shape of the organelle, and an inner membrane, called cristae, that is folded inwards
Why are mitochondria referred to as the powerhouses of the cell?
Because the reactions of aerobic respiration take place in the mitochondria, and because aerobic respiration releases about 95% of the energy needed to keep a cell alive
What is anaerobic respiration?
Anaerobic respiration uses glucose to produce lactic acid and two ATP molecules in the absence of oxygen.
- Means respiration without oxygen.
What happens if there is no oxygen available in anaerobic respiration?
If no oxygen is available, the pyruvate produced in glycolysis is then converted to lactic acid by fermentation. The
What is aerobic respiration?
Aerobic respiration uses oxygen to convert glucose into carbon dioxide and water, producing up to 38 molecules of ATP per glucose molecule.
What is pyruvate produced from glycolysis broken down into?
It’s completely broken down to carbon dioxide and water. This is known as aerobic respiration – respiration requiring oxygen.
Where does aerobic respiration occur?
In the mitochondria of the cell.
What must happen to complete the breakdown of glucose?
The two pyruvate molecules produced in glycolysis must enter a mitochondrion, where enzymes are available to allow the next series of reactions to occur.
What is the first stage of cellular respiration?
Glycolysis
What happens during Glycolysis?
- Means ‘splitting glucose’
- Doesn’t require oxygen (Anaerobic)
- Glucose molecule is broken down into a pair of 3 carbon molecules called pyruvate
- Requires 2 ATP to begin
- Makes 4 (2 new) ATP, 2 pyruvate and NADH
What is NADH?
An energy rich morsel
What happens if there is no energy readily available during glycolysis?
- Pyruvate converted to lactic acid
- Lactic acid taken to liver in bloodstream and combine with oxygen to form glucose - later glycogen
- During anaerobic respiration an oxygen debt is accumulated and must be ‘repaid’ by heavy breathing.
What type of process is the Krebs cycle?
An aerobic process. However, it uses oxygen indirectly.
Where does the Krebs cycle occur?
Occurs in the inner membrane of the mitochondria called the ‘cristae’
What does the Krebs cycle do to the products?
- Reworks these 2 Pyruvate into 2 ATP molecules per glucose molecules
- 1 pyruvate becomes oxidised and combines with oxygen
- The other loses a 3-carbon chain which combines with oxygen to form carbon dioxide and exits the cell
What happens after the pyruvate is broken down?
Pyruvate is converted to ‘Acetyl Coenzyme A’ (Acetyl CoA) by removing the Co2 molecules.
- 2 more NADH is also formed.
- Makes 2 ATP per pyruvate
- Eventually forms citric acid
What happens at the end of the Krebs Cycle?
- Carbon dioxide is exhaled.
- At the end of this stage, we have: 6 NADH, 4 CO2, 2 ATP, 2 FADH
