2.1 Metabolic Pathways Flashcards
What are metabolic pathways?
Metabolic pathways are integrated and controlled pathways of enzyme catalysed reactions within a cell
Define an anabolic reaction
Anabolic reactions build up large molecules from smaller molecules and requirers energy
Define a catabolic reaction
Catabolic reactions break down larger molecules into smaller molecules and release energy
Give examples of catabolic reactions
Breakdown of…
Carbohydrates
Fats
Proteins
Give examples of anabolic reactions
The synthesis of… Starch Fats Proteins Nucleic acids
The importance of reversible and irreversible steps
They allow the process to be kept under control
What controls metabolic pathways?
Enzymes
Give three features of metabolic pathways
they can have reversible steps, irreversible steps and alternative routes.
What type of reaction builds up large molecules from smaller molecules
Anabolic
Describe the difference between anabolic and catabolic reactions
Anabolic reactions involve the building up of small molecules to larger more complex molecules - requires energy.
Catabolic reactions breakdown of large molecules into smaller simpler molecules - releases energy.
Anabolic or catabolic;
Synthesis of protein from amino acids
Anabolic
Anabolic or catabolic;
Aerobic respiration
Catabolic
Anabolic or catabolic;
Digestion of fatty acids into glycerol
Catabolic
Anabolic or catabolic;
Synthesis of glycogen from glucose
Anabolic
Define the nucleus
Controls the activities of the cell
Roll of the cell membrane
Controls the entry and exit of substances in the cell
Roll of cytoplasm
Site of chemical reactions
Roll of the vacuole
Maintains cell shape and contains cell sap
Roll of the cell wall
Provides snd Maintains shape
Roll of chloroplasts
Site of photosynthesis
Roll of ribosome
Site of protein synthesis
Roll of mitochondria
Site of energy synthesis
What is active transport?
The movement of molecules or ions across the plasma membrane against a concentration gradient
What are the two components of the plasma membrane?
Phospholipid and protein
Funtions of pump - membrane
Recognise and transport specific ions across the membrane
Functions of pores - membrane
Allow larger molecules to diffuse across a membrane
How are metabolic pathways controlled?
Metabolic pathways are controlled by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
What is ‘induced fit’?
Induced fit and the role of the active site of an enzyme in affecting activation energy and the affinity of the substrate and products for the active site.
List features of an enzyme
Speed up chemical reactions
lower the activation energy needed for a reaction to occur
are unchanged at the end
have an active site which is complementary to a particular substrate, are specific to their substrates
Compare the infinity of a substrate and the affinty of a product for the active site
substrate has a high affinity and product has low affinity
How will the presence of a substrate or the removal of a products affect reactions
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.
Factors affecting enzyme action
Temperature
Ph
Supply of substrate
Enzymes are biological catalysts, outline THREE features of catalysts
Speed up the rate of a chemical reaction
Take part in the reaction but remain unchanged at the end They lower the activation energy
What determines the structure of an enzyme’s active site?
The sequence of amino acids
and the subsequent additional bonding between amino acids
Define the infinity of the substrate to the active site
High
Define the inifnity of the product to the active site
Low
List how metabolic pathways are controlled
through competitive, non-competitive and feedback inhibition of enzymes.
Define competitive inhibitors
Competitive inhibitors have a very similar shape to that of the substrate.
• They bind at the active site and prevent the substrate from binding. The rate of reaction is slows down.
• Competitive inhibition is reversed by increasing substrate concentration.
Define non-competitive inhibitors
- A non-competitive inhibitor binds away from the active site of the enzyme molecule.
- This changes the shape of the active site and prevents the substrate from binding with the enzyme.
- An increase in substrate concentration has no effect on the rate of reaction as it is not competing with the substrate for the active site.
- Non-competitive inhibition cannot be reversed by increasing substrate concentration.
When will feedback inhibition occur?
What the product concentration resches critical
