Main content
High school biology
Course: High school biology > Unit 3
Lesson 1: Introduction to metabolismIntroduction to metabolism review
Key Terms
| Term | Meaning |
|---|---|
| Metabolism | The sum of all chemical reactions that take place inside a cell |
| Anabolism | The synthesis of complex molecules from simpler ones |
| Catabolism | The breakdown of complex molecules into simpler ones |
| Exergonic reaction | A reaction that releases energy |
| Endergonic reaction | A reaction that consumes energy |
| ATP | Adenosine triphosphate, the primary energy carrier in living things |
Metabolism
Metabolism is a set of chemical reactions that interconnect in a series of pathways. It is a balancing act between the building and breakdown of molecules in the body.
| Type of metabolism | Process | Energetics | Example |
|---|---|---|---|
| Anabolism | Builds complex molecules from simple ones | Endergonic | Production of new body tissues |
| Catabolism | Breaks down complex molecules into simpler ones | Exergonic | Digestion of food |
Examples
Catabolism: Cellular respiration
Cellular respiration is a catabolic process during which glucose is broken down to release usable energy for a cell.
The overall reaction for cellular respiration is:
start text, C, end text, start subscript, 6, end subscript, start text, H, end text, start subscript, 12, end subscript, start text, O, end text, start subscript, 6, end subscript + 6, start text, O, end text, start subscript, 2, end subscript → 6, start text, C, O, end text, start subscript, 2, end subscript + 6, start text, H, end text, start subscript, 2, end subscript, start text, O, end text + start text, e, n, e, r, g, y, end text
As in all catabolic processes, cellular respiration releases energy which can then be harnessed and used by other reactions in the cell.
Anabolism: Photosynthesis
Photosynthesis is an anabolic process during which plants use energy from sunlight to convert carbon dioxide gas and water into sugar molecules.
The overall reaction for photosynthesis is:
6, start text, C, O, end text, start subscript, 2, end subscript + 6, start text, H, end text, start subscript, 2, end subscript, start text, O, end text + start text, e, n, e, r, g, y, end text → start text, C, end text, start subscript, 6, end subscript, start text, H, end text, start subscript, 12, end subscript, start text, O, end text, start subscript, 6, end subscript + 6, start text, O, end text, start subscript, 2, end subscript
Photosynthesis, like all anabolic processes, consumes energy as glucose is built. Some of this glucose is used by the plant itself, or it can be used as a food source for other organisms.
Common mistakes and misconceptions
- Many metabolic reactions occur at the same time. Thousands of metabolic reactions are being carried out in your body at the same time. They are all coordinated with one another and regulated carefully to keep an organism functioning properly.
Want to join the conversation?
The more I know, I more I get confused with the concept of 'energy'. It seems to me that energy is very abstract, like an invisible force that pushes things around. So what exactly is energy?(19 votes)
Energy is what it takes to do work, mostly moving matter in the form of vibration/heat, rotation, and kinetic energy. Potential energy is the stored ability to do work. It is a name chosen for a specific unit.(11 votes)
This is hard and confusing (probably because i am a 6th grader)(8 votes)
9th grade now, is it any easier?(6 votes)
I am a 11th grader and I am preparing to study medicine. Can anyone tell me if I have to know all the metabolic reactions such as glycolysis, glucogenesis... ?(9 votes)- Yes, you should know all of these metabolic reactions.(2 votes)
How does Cellular respiration work?(6 votes)- hey mate, there are articles on cellular respiration in the next unit.(3 votes)
Why is photosynthesis an anabolic process and why is cellular respiration a catabolic process?(4 votes)
Anabolic processes are processes that build up compounds. That means higher energy bonds are created. Photosynthesis takes CO2 and H2O (quite low energy molecules), and then assembles them into glucose. Catabolism, which is the process of digestion and break down complex chemicals into simpler molecules.(4 votes)
In the Metabolism section in this article, it shows a chart. Under Energetics it shows Endergonic and Exergonic. What do those mean?(4 votes)
Endergonic is a reaction that consumes energy and is involved in anabolism. Exergonic is a reaction that releases energy and is involved in catabolism.(0 votes)
- why are large molecules broke down into small molecules?(3 votes)
- I'm a bit confused about this. So anabolism is an endergonic process, however, it requires bond-making. Isn't bond-making a process that releases energy? The opposite occurs in catabolism right?
Please help!(3 votes) 
how do metabolic functions affect my everyday life?(2 votes)- Metabolism is a process of creating energy(ATP). This energy is used in all of your movements and bodily fuctions.(1 vote)
When metabolic reactions occur?(2 votes)
Metabolic reactions may be categorized as catabolic – the breaking down of compounds (for example, the breaking down of glucose to pyruvate by cellular respiration); or anabolic – the building up (synthesis) of compounds (such as proteins, carbohydrates, lipids, and nucleic acids).(1 vote)