Unit 1 KA6 Metabolic Pathways Flashcards
Stuff gets broken and stuff gets made
Define metabolism
All the chemical reactions that occur within the human body
What are anabolic pathways?
Enzyme pathways that require energy and involve biosynthetic (building up small molecules to larger ones) processes
What are catabolic pathways?
Enzyme pathways that release energy and involve the breakdown of molecules to smaller ones
What is activation energy?
The energy require to break chemcial bonds in the reactants to start a chemical reaction
What is the state at which chemical bonds become unstable due to absorbing too much energy called?
The transition state
What is a catalyst?
A substance that:
*Lowers the activation energy of a reaction by providing an alternative reaction pathway
* Speeds up the reaction rate
* Takes part in the reaction but remains unchanged by the end of it
What is a biological catalyst?
An enzyme
What are enzymes made of?
Protein
Why do enzyme active sites only bind to specific substrates?
The active site has a specific shape
due to the structure and bonding of the amino acids in the polypeptide chain
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Substrate molecules have high ____ for the active site
affinity
The products have a ____ affinity for the active site
low
What does affinity mean?
The strength of attraction between the molecules.
What is induced fit?
When the enzyme’s active site changes shape to better fit the substrate
How does induced fit help the reaction?
It insures that the active site is very close to the substrate and thus increases the chance of the reaction taking place
How are the reactants’ orientation determined in enzyme reactions with multiple reactants?
The shape of the active site determines the orientation
This holds the reactants tightly together, in a way that ensures the reaction can take place
What factors affect enzyme reactions?
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
What do inhibitors do to the reaction rate?
slow it down or bring it to a halt
What happens to the reaction rate as substrate concentration increases?
Increases, then eventually remains constant as the active sites are all occupied, meaning the enzyme concentration is now the limiting factor
How can metabolic pathways be controlled?
- Presence of an enzyme
- Absence of an enzyme
- Key enzymes regulating the rate of a reaction within a metabolic pathway
How are enzymes who’s genes are continually expressed controlled?
regulation of their rate of reaction
Most enzyme reactions are reversible
What determines the direction of reaction?
The concentration of the substrates and products
What is an inhibitor?
A substance that decreases the rate of an enzyme controlled reaction
What is a competitive inhibitor?
An inhibitor that competes with the substrate for the enzyme’s active sites
It binds to the enzyme’s active site, preventing the substrate from binding to the active site, reducing enzyme activity and thus the rate of reaction
What is the structure of competitive inhibitors?
Similar molecular structure to the enzyme’s substrate
