Metabolic Pathways Flashcards
What are metabolic pathways? (2)
-Integrated and controlled pathways of enzyme-catalysed reactions within a cell.
- can be described as chemical reactions that start with a substrate and finish with an end product
What types of steps can metabolic pathways have?
Reversible steps, irreversible steps, and alternative routes.
What are the two main types of reactions in metabolic pathways?
Anabolic and catabolic reactions.
What do anabolic reactions do?
Build up large molecules from small molecules and require energy. (biosynthetic reactions)
What do catabolic reactions do?
Break down large molecules into smaller molecules and release energy.
(Breakdown reactions)
Where are protein pores, pumps, and enzymes found?
Embedded in membranes.
What are protein pumps, what do they do?
They act as carrier molecules and recognise specific ions and transfer them across the cell membrane.
What are protein pores? What do they do?
Pores are contained Inside transport molecules, which allow ions of a particular size to pass through the membrane.
What is the role of enzymes in metabolic pathways?
Enzymes act as catalysts that speed up chemical reactions in metabolic pathways.
Are Enzymes consumed in the reactions they catalyse?
Enzymes are not consumed and can be reused.
The specific region of an enzyme where substrate molecules bind is called the ______.
active site
What is feedback inhibition? (3)
-Feedback inhibition occurs when the end product in a metabolic pathway reaches a critical concentration
-where the end product of a metabolic pathway binds to an enzyme at the start of the pathway.
-This process stops the metabolic pathway and so prevents further synthesis of the end product till the concentration of end products decreases.
Which 4 factors can affect enzyme activity?
Temperature
pH
substrate concentration
enzyme concentration
What is the difference between competitive and non-competitive inhibition?
Competitive inhibition occurs when an inhibitor competes with the substrate for the active site, while non-competitive inhibition occurs when an inhibitor binds to a different part of the enzyme and changes the active site shape.
True or False: Enzymes lower the activation energy required for a reaction to proceed.
True
What is the role of enzymes in metabolic pathways?(2)
Enzymes regulate and control metabolic pathways to prevent the build-up of unnecessary end products.
Enzymes can control the pathway by their presence or absence, as well as by regulating the reaction rates.
What is an active site? (4)
-The active site is the region on an enzyme where substrates bind and reactions occur.
-It can change shape slightly when the substrate is bound.
- it has a high affinity to the substrate
-It is specific to the substrate and facilitates the reaction.
Induced fit
Induced fit is when the active site of the enzyme changes shape slightly to fit the substrate better after binding.
What happens to the binding affinity of products to the enzyme after the reaction?
Products have a low affinity to the enzyme and are released after the reaction.
How do enzymes affect the activation energy of a reaction?
Enzymes lower the activation energy needed for a reaction to occur, Which makes the metabolic pathway more efficient.
What drives the direction of reversible metabolic reactions?
The presence of a substrate or removal of a product drives reversible metabolic reactions in a particular direction.
What is a factor that affects the rate of enzyme reaction?
Substrate concentration
What happens to the enzyme reaction rate as substrate concentration increases?
It increases until all active sites are occupied
What occurs when all active sites of an enzyme are occupied?
The enzyme is saturated. At the saturation point adding more substrates makes no difference to the reaction rate.
What is the role of inhibitors in metabolic pathways?
Inhibitors can stop an enzyme from binding to its substrate, controlling the progress of a metabolic pathway.
Name the three types of inhibition.
-Competitive inhibition
-Non-competitive inhibition
- Feedback inhibition
What is competitive inhibition? (2)
A type of inhibition where an inhibitor competes with the substrate for the active site of an enzyme.
This reduces the enzyme’s ability to bind to its substrate.
What is an enzyme?
An enzymes are biological catalysts.
They speed up chemical reactions by lowering the activation energy.
What is affinity in the context of enzymes?
Affinity refers to the chemical attraction between the substrate and the active site of the enzyme.
What determines the orientation of reactants in an enzymatic reaction?
The shape of the active site.
