1.6 Cell Metabolism Flashcards
Definition of cell metabolism
All the enzyme controlled reactionsthat occur in a cell at the same time
The two groups that reactions in a cell can be categorised into
- Catabolic
* Anabolic
Explain an anabolic pathway
- Requires energy
* Involves biosynthetic processes (large molecules synthesised from small molecules)
Explain a catabolic pathway
- Releases energy
* Involves the breakdown of large molecules into smaller molecules
An example of a catabolic reaction
Aerobic respiration
An example of an anabolic pathway
Protein synthesis
Definition of a metabolic pathway
A series of chemical reactions that follow on, one after the other
What each stage in a metabolic pathway is controlled by
Enzymes
Example of a reversible metabolic pathway
The conversion of pyruvate into lactic acid in animal cells
Example of an irreversible metabolic reaction
The conversion of pyruvate into ethanol and CO2 in plant cells
What alternative routes do in metabolic reactions
Bypass steps in a pathways
The two ways metabolic pathway can be controlled
- the presence or absence of particular enzymes in the pathway
- regulation of the rate of reaction of key enzymes within the pathway
The result of the genes for some enzymes being continuously expressed
- the enzymes are always present in the cell
* their control involves the regulation of their rate of reaction
The two molecules regulation of rate of reaction is controlled by
- intracellular
* extracellular
Describe the work of extracellular signal molecules
Secreted by a particular cell but work elsewhere in the body
Example of extracted signal molecules
Hormones which travel in the bloodstream to reach target tissues
eg. Insulin produced in the pancreas works on the liver
Describe the work of intracellular signal molecules
Work inside the cell that produces them
Where enzymes are found
Every living cell
What an enzyme is
Biological catalysts made of protein
What would happen if enzymes weren’t present in cells
Chemical reactions would occur in cells to slowly for life to exist
What activation energy is
The energy needed to start a reaction
Basic work of enzymes
Enzymes lower the activation energy needed to start a chemical reaction
Symbol for activation energy
Ea
Define what is ment by affinity
The active site having a chemical attraction to the substrate