Unit 2: KA1 Metabolic Pathways Flashcards
Metabolism refers to all of the chemical reactions that take place inside living cells. Unicellular and multicellular organisms must control their metabolism in order to survive.
What are metabolic pathways?
[Course spec.]
Integrated and controlled pathways of enzyme-catalysed reactions within a cell.
What can metabolic pathways have? [3 marks]
Reversible steps [1],
Irreversible steps [1] and,
Alternative routes [1].
Reactions within metabolic pathways can be…
ANABOLIC or CATABOLIC.
Describe ANABOLIC reactions. [2 marks]
Anabolic reactions BUILD UP large molecules from small molecules [1] and REQUIRE ENERGY [1].
Describe CATABOLIC reactions. [2 marks]
Catabolic reactions BREAK DOWN large molecules into small molecules [1] and RELEASE ENERGY [1].
Where can you find protein pores, pumps and enzymes?
Embedded in membranes.
What are metabolic pathways controlled by? [2 marks]
The presence or absence of particular enzymes [1] and the regulation of the rate of reaction of key enzymes [1].
When does “induced fit” occur?
When the active site changes shape to better fit the substrate after the substrate binds.
*Not acceptable to use the “lock & key” analogy anymore apparently.
What does “affinity” mean?
The degree to which a substance tends to combine with another.
*Also (in a different context) means, having a natural liking for and understanding of someone or something. If you have high affinity for something, you’re “closer” to it.
The substrate molecule(s) have a low affinity for the active site and in turn, the subsequent products have high affinity, allowing them to stick to the active site. True or False?
False - substrates have HIGH affinity for the active site. The subsequent products have a LOW affinity, allowing them to leave the active site.
Some metabolic reactions are ———- and the presence of a substrate/removal of a product will…
REVERSIBLE.
…Drive a sequence of reactions in a particular direction.
What are COMPETITIVE inhibitors?
Competitive inhibitors bind at the active site preventing the substrate from binding.
How can competitive inhibition be reversed?
By INCREASING substrate concentration.
What are NON-COMPETITIVE inhibitors?
Non-competitive inhibitors bind away from the active site but change the shape of the active site, preventing the substrate from binding.
Can we reverse non-competitive inhibition by increasing the substrate concentration?
No. Non-competitive inhibition cannot be reversed by increasing substrate concentration.
