1.6 Flashcards
What are metabolic pathways?
integrated and controlled pathways of enzyme controlled reactions within a cell.
What is a catabolic pathway?
a substrate is usually a large molecule and the products are small molecules. Energy is released.
What is a anabolic pathway?
a substrate is usually a small molecule and the products are large molecules. Energy is required.
Can metabolic pathways be reverisible or are they irreversible?
In some cases, these steps can be reversed, whereas others are irreversible, so that once that reaction has taken place the metabolite must pass onto a new stage in the pathway.
What are metabolic pathways controlled by?
- Presence or absence of particular enzymes
- Regulation of the rate of reaction of key enzymes
Why can’t living cells tolerate high temperature?
Living cells cannot tolerate the high temperature needed to make chemical reactions proceed at a rapid rate. Therefore, they make use of biological catalysts called enzymes.
What is the function of enzymes?
large complex proteins folded into a specific shape so they can fit a particular substrate. This basic theory is referred to as the lock and key hypothesis. Enzymes only act on one specific substrate which is complementary to and fits into the active site.
Describe the active site and the induced fit
The active site is flexible and dynamic. When a substrate enters the active site, the active site can change shape slightly to better fit the substrate after the substrate binds. This is called an induced fit which ensures that the active site on the enzyme comes into very close contact with the molecules of substrate and increases the chance of a reaction taking place.
What has a high affinity for the active site?
The substrate(s) have a high affinity for the active site.
WHat has a low affinity for the active site?
The product(s) have a low affinity for the active site.
What is the orientation of the reactants?
When the reaction involves two (or more) substrates, the shape of the active site determines the orientation of the reactants. This ensures that they are held together in such a way that the reaction between them can take place.
What is activation energy?
The energy needed to break chemical bonds in the reactant chemicals is called the activation energy. The bonds break when the molecules of the reactant have absorbed enough energy to make them unstable. They are now in the transition state and the reaction can occur. This means that the presence of an enzyme lowers the activation energy making it easier to start a reaction.
Are metabolic pathways reversible?
Some metabolic reactions are reversible and the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction.
What has an impact on the recation rate?
As the substrate concentration increases more and more of the enzyme’s active site becomes used, until a point is reached when no more are available.
At a low concentration of substrate, the reaction rate is low since there are too few substrate molecules present.
This increase continues until a point is reached where increasing the substrate concentration fails to make the reaction happen faster.
WHat are the three types on inhibition?
Competitive, Non – competitive and Feedback Inhibition
