12.1 - Glycolysis Flashcards
What are the two different forms of cellular respiration
- Aerobic respiration: requires oxygen and produces carbon dioxide, water and much ATP.
- Anaerobic respiration: takes place in the absence of oxygen and produces lactate (in animals) or ethanol and carbon dioxide (in plants and fungi) but only a little ATP in both cases.
What are the 4 stages of aerobic respiration
1) glycolysis
2)link reaction
3) Krebs cycle
4) oxidative phosphorylation
Briefly summarise what happens in glycolysis
the splitting of the 6-carbon glucose molecule into two 3-carbon pyruvate molecules
Briefly summarise what happens in the link reaction
the 3-carbon pyruvate molecules enter into a series of reactions which lead to the formation of acetylcoenzyme A, a
2-carbon molecule.
Briefly describe what happens in the Krebs cycle
the introduction of acetylcoenzyme A into a cycle of oxidation-reduction reactions that yield some ATP and a large quantity of reduced NAD and FAD (Topic
Briefly summarise what happens in oxidative phosphorylation
the use of the electrons, associated with reduced NAD and FAD, released from the Krebs cycle to synthesise ATP with water produced as a by-product.
Describe the steps of glycolysis
1) phosphorylation of glucose to glucose phosphate: Before it can be split into two, glucose must first be made more reactive by the addition of two phosphate molecules (phosphorylation).
The phosphate molecules come from the hydrolysis of two ATP molecules to ADP. This provides the energy to activate glucose and lowers the activation energy for the enzyme-controlled reactions that follow (Topic 1.7).
2) splitting of the phosphorylated glucose: Each glucose molecule is split into two 3-carbon molecules known as triose phosphate.
3) oxidation of triose phosphate: Hydrogen is removed from each of the two triose phosphate molecules and transferred to a hydrogen-carrier molecule known as NAD to form reduced NAD.
4) the production of ATP: Enzyme-controlled reactions convert each triose phosphate into another 3-carbon molecule called pyruvate. In the process, two molecules of ATP are regenerated from ADP.
What is the overall yield from glycolysis
- two reduced NAD
- net two ATP
- two Pyruvate
What does the universality of glycolysis provide evidence for?
Indirect evidence for evolution, as it is a universal feature in all living organisms.
Where does glycolysis occur in cells?
In the cytoplasm, without the need for any organelle or membrane.
What happens to pyruvate in anaerobic respiration?
Pyruvate is converted into lactate or ethanol to re-oxidise NAD, allowing glycolysis to continue.
How much energy does anaerobic respiration yield compared to aerobic respiration?
Anaerobic respiration yields only a small fraction of the potential energy in pyruvate.
How do most organisms release the remainder of energy stored in pyruvate?
By using oxygen to break down pyruvate further during aerobic respiration.
Fill the gaps:
Glycolysis takes place in the (1)of cells and begins with the activation of the main respiratory substrate, namely the hexose sugar called (2). This activation involved the addition of two (3) molecules provided by two molecules of (4). The resultant activated molecule is known as (5) and in the next stage of glycolysis it is split into two molecules called (6). The third stage entails the oxidation of these molecules by the removal of (7), which is transferred to a carrier molecule called (8). The final stage is the production of the 3-carbon molecule (9), which also results in the formation of two molecules of (10).
1) cytoplasm
2) glucose
3) phosphate
4) ATP
5) phosphorylated glucose
6) triose phosphate
7) hydrogen
8) NAD
9) pyruvate
10) ATP
