Session 6-Enzymes Flashcards
Complete the sentence:
The phosphorylation of glucose is ___________ but it needs activation energy because negatively charged ______ atoms repel each other and the reaction is catalysed by the enzyme __________.
Spontaneous
Oxygen
Hexokinase
How is the phosphorylation of glucose catalysed?
By providing positive charges from the side chains on the AA of hexokinase
In which three ways can you increase the rate of reaction?
- Increasing the temperature-increases the number of molecules with the activation energy
- Increasing the concentration-increases the chance of molecular collisions
- Enzymes-biological catalysts that increase rate by lowering activation energy and facilitating the formation of the transition state
What is the transition state?
The high energy intermediate that lies between the substrate and product
What are some features of enzymes? (4)
Highly specific
Unchanged after reaction
Do not affect reaction equilibrium
Increase rate of reaction
True or false: most of the enzyme acts as a scaffold to create the active site
TRUE
Complete the sentence:
Substrate molecules are bound in the _____ or _______ that usually excludes water
Cleft
Crevice
What shape is the graph of reaction velocity against substrate concentration?
Rectangular hyperbola
Define Vmax
Maximal rate when all enzyme active sites are saturated with substrate
Define Km
Substrate concentration that gives half maximal velocity
Complete the sentence:
Km values give a measure of the ________ of an enzyme for its substrate
Affinity
What does a low Km value mean?
Enzyme has a high affinity for its substrate
What does a high Km value mean?
Enzyme has a low affinity for its substrate
What is 1 unit equal to?
The amount of enzyme that converts 1 micromol of product per minute under standard conditions
True or false: the rate of enzyme catalysed reaction is proportional to the concentration of the enzyme
TRUE
