2.7.1
Overview of Respiration
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Respiration
Respiration is a series of reactions that convert chemical energy stored in carbohydrates into ATP. It takes place in the mitochondria of eukaryotic cells.

Importance of respiration
- Respiration is the process that converts energy within the bonds of glucose into a more readily available form: ATP. The equation for respiration is:
- 6O2 + C6H12O6 (glucose) → 6CO2 + 6H2O

Types of respiration
- There are two types of respiration:
- Aerobic - respiration using oxygen.
- Anaerobic - respiration without oxygen.
- Both types of respiration start with the same stage: glycolysis (pictured).


Anaerobic respiration
- Anaerobic respiration does NOT use oxygen (e.g. short burst of intense exercise).
- There are two types of anaerobic respiration:
- Ethanol fermentation - takes place in plants and yeast.
- Lactate fermentation - takes place in animals.

Aerobic respiration
- Aerobic respiration uses oxygen (e.g. extended periods of exercise).
- The reaction and products are the same in plants, animal and yeast.
- Aerobic respiration also differs from anaerobic respiration in the following ways:
- Water is produced.
- More ATP is produced.
- Glucose is fully broken down.
- After glycolysis, there are more steps (the link reaction, the Krebs cycle and oxidative phosphorylation).
Glycolysis
Respiration produces ATP and can be either aerobic or anaerobic. Glycolysis is the first stage in both these processes. Glycolysis happens in the cytoplasm and is an anaerobic process.

Phosphorylation
- The first step in glycolysis involves the phosphorylation of glucose to glucose phosphate using one molecule of ATP.
- Glucose phosphate is phosphorylated by another molecule of ATP to hexose bisphosphate (a six-carbon molecule)
- Hexose bisphosphate splits into two molecules of triose phosphate (TP).

Oxidation
- The two molecules of TP are oxidised to pyruvate (another three-carbon molecule) in a multi-step reaction.
- A single TP molecule produces two molecules of ATP and one molecule of reduced NAD (NADH) in this process.

Net gain
- 2 ATP molecules.
- 2 NADH molecules.
1Unity & Diversity - Molecules
1.1Water
1.2DNA Structure & Replication
1.3Transcription & Gene Expression
2Unity & Diversity - Cells
2.1The Origin of Cells
2.2Introduction to Cells
2.3Ultrastructure of Cells
2.4Cell Division
2.5Structure of DNA & RNA
2.6DNA Replication, Transcription & Translation
2.7Cell Respiration
2.8Photosynthesis
2.9Viruses
3Unity & Diversity - Organisms
3.1Diversity of Organisms
3.2Evidence for Evolution
4Unity & Diversity - Ecosystems
4.1Classification
4.3Evolution & Speciation
4.3.1Evidence for Evolution - Fossils & DNA4.3.2Evidence for Evolution - Anatomy & Geography4.3.3IB Multiple Choice - Evidence for Evolution4.3.4Extended Response - DNA & Evolution4.3.5Populations4.3.6Mutations, Genetic Drift, & Gene Flow4.3.7Speciation4.3.8Rate of Speciation4.3.9Allopatric & Sympatric Speciation
4.4Conservation of Biodiversity
5Form & Function - Molecules
6Form & Function - Cells
6.1Membranes & Membrane Transport
6.2Organelles & Compartmentalization
6.3Cell Specialization
7Form & Function - Organisms
7.2Transport
7.3Muscle & Motility
8Form & Function - Ecosystems
8.1Species, Communities & Ecosytems
8.3Carbon Cycle
9Interaction & Interdependence - Molecules
9.1Enzymes
9.2Metabolism
9.3Cell Respiration
10Interaction & Interdependence - Cells
10.1Chemical Signalling
10.2Neural Signalling
10.3Adaptation to Environment
10.4Ecological Niches
11Interaction & Interdependence - Organisms
11.1Integration of Body Systems
12Interaction & Interdependence - Ecosystems
12.1Populations & Communities
12.2Transfers of Energy & Matter
13Continuity & Change - Molecules
13.1DNA Replication
13.2Protein Synthesis
14Continuity & Change - Cells
15Continuity & Change - Organisms
15.1Inheritance
15.1.1Non-Nuclear Inheritance15.1.2Linked Genes15.1.3IB Multiple Choice - Non-Mendelian Genetics15.1.4Extended Response - Inheritance15.1.5Introduction to Non-Mendelian Inheritance15.1.6Chi-Squared Test15.1.7End of Topic Quiz - Inheritance15.1.8Sex-Linked Genes15.1.9Grade 4-5 (Scientific Practices) - Inheritance
16Continuity & Change - Ecosystems
16.1Natural Selection
16.2Stability & Change
Jump to other topics
1Unity & Diversity - Molecules
1.1Water
1.2DNA Structure & Replication
1.3Transcription & Gene Expression
2Unity & Diversity - Cells
2.1The Origin of Cells
2.2Introduction to Cells
2.3Ultrastructure of Cells
2.4Cell Division
2.5Structure of DNA & RNA
2.6DNA Replication, Transcription & Translation
2.7Cell Respiration
2.8Photosynthesis
2.9Viruses
3Unity & Diversity - Organisms
3.1Diversity of Organisms
3.2Evidence for Evolution
4Unity & Diversity - Ecosystems
4.1Classification
4.3Evolution & Speciation
4.3.1Evidence for Evolution - Fossils & DNA4.3.2Evidence for Evolution - Anatomy & Geography4.3.3IB Multiple Choice - Evidence for Evolution4.3.4Extended Response - DNA & Evolution4.3.5Populations4.3.6Mutations, Genetic Drift, & Gene Flow4.3.7Speciation4.3.8Rate of Speciation4.3.9Allopatric & Sympatric Speciation
4.4Conservation of Biodiversity
5Form & Function - Molecules
6Form & Function - Cells
6.1Membranes & Membrane Transport
6.2Organelles & Compartmentalization
6.3Cell Specialization
7Form & Function - Organisms
7.2Transport
7.3Muscle & Motility
8Form & Function - Ecosystems
8.1Species, Communities & Ecosytems
8.3Carbon Cycle
9Interaction & Interdependence - Molecules
9.1Enzymes
9.2Metabolism
9.3Cell Respiration
10Interaction & Interdependence - Cells
10.1Chemical Signalling
10.2Neural Signalling
10.3Adaptation to Environment
10.4Ecological Niches
11Interaction & Interdependence - Organisms
11.1Integration of Body Systems
12Interaction & Interdependence - Ecosystems
12.1Populations & Communities
12.2Transfers of Energy & Matter
13Continuity & Change - Molecules
13.1DNA Replication
13.2Protein Synthesis
14Continuity & Change - Cells
15Continuity & Change - Organisms
15.1Inheritance
15.1.1Non-Nuclear Inheritance15.1.2Linked Genes15.1.3IB Multiple Choice - Non-Mendelian Genetics15.1.4Extended Response - Inheritance15.1.5Introduction to Non-Mendelian Inheritance15.1.6Chi-Squared Test15.1.7End of Topic Quiz - Inheritance15.1.8Sex-Linked Genes15.1.9Grade 4-5 (Scientific Practices) - Inheritance
16Continuity & Change - Ecosystems
16.1Natural Selection
16.2Stability & Change
Practice questions on Overview of Respiration
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- 1What are the two types of respiration?Fill in the list
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- 4What is the net gain of glycolysis?Multiple choice
- 5
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