Cellular respiration and energy systems in muscle cells Flashcards
State the three types of aerobic respiration are
The three pathways of aerobic respiration are:
• Glycolysis
• Citric acid Cycle
• Electron transport chain
Describe Glycolysis
Glycolysis is one of the three main pathways of aerobic respiration and involves the breakdown of glucose to pyruvate.
ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase of glycolysis. (2 ATP)
The leads to the generation of more ATP during the energy pay-off stage (4 ATP) and results in a net gain of ATP (net gain of 2 ATP
What is the role of dehydrogenase
Dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH. This occurs in both glycolysis and the citric acid cycle.
The hydrogen ions and electrons from NADH are passed to the electron transport chain on the inner mitochondrial membrane
Describe the citric acid cycle
The citric acid cycle is one of the three main pathways of aerobic respiration.
In aerobic conditions, pyruvate is converted into an acetyl group that combines with coenzyme A forming acetyl coenzyme A. NADH and carbon dioxide are also formed during this process.
In the citric cycle, the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate. During a series of enzyme-controlled steps, citrate is gradually converted back into back into oxaloacetate which results in the generation on ATP and release of carbon dioxide.
Where does glycolysis
cytoplasm
Where does the citric acid cycle take place
Matrix of the mitochondria
Where does the electron transport chain occur
Proteins within the inner mitochondrial membrane
describe the impact of excersise on muscle cells
Muscle cells during vigorous exercise do not get sufficient oxygen to support the electron transport chain. Under these conditions, pyruvate is converted to lactate.
How is lactate produced
When pyruvate is converted into lactate, this involves the transfer of hydrogen ions from the NADH produced in glycolysis to pyruvate in order to produce lactate.
• This regenerates the NAD needed to maintain ATP production though glycolysis.
describe muscle fatigue and oxygen debt
As lactate accumulates muscle fatigue occurs.
• The oxygen debt is repaid when exercise is complete. This allows respiration to provide the energy to convert lactate back to pyruvate and glucose in the liver.
describe slow twitch muscles
Slow-twitch muscles fibres contract relatively slowly but can sustain contractions for longer.
• They are useful for endurance activities such as long- distance running, cycling or cross-country skiing.
• Slow-twitch muscle fibres rely on aerobic respiration to generate ATP and have many mitochondria, a large blood supply and a high concentration of the oxygen-storing protein myoglobin.
• The major storage fuel of slow-twitch muscle fibres is fat.
describe fast twitch muscles
Fast-twitch muscle fibres contract relatively quickly, over short periods. They are useful for activities such as sprinting or weightlifting.
• Fast-twitch muscle fibres can generate ATP through glycolysis only and have fewer mitochondria and a lower blood supply compared to slow twitch muscle fibres.
• The major storage fuel of fast-twitch muscle fibres is glycogen.
describe the patterns of muscle tissues in athletes
Most human tissue contains a mixture of both slow- and fast-twitch muscle fibres.
• Athletes show distinct patterns of muscle fibres that reflect their sporting activities
