Endocrine Flashcards
What is a catalyst
A catalyst is a molecule that increases the rate of a reaction without being consumed itself.
They lower the activation energy without altering the equilibrium or free energy change of a reaction.
What is an Enzyme
An enzyme is a biological catalyst that structurally facilitates a chemical reaction.
Mainly Globular Proteins
They posses an active site within which chemical reactions take place
They lower activation energy and thus speed up recations increasing the reaction rate
What is Activation energy
The minimum energy required for an rection to take place
Why are enzymes generally ineffective catalysts over a broad temperature range?
Enzymes must be at a certain optimal temperature to maintain their structure.
The structure of an enzyme, especially in relation to its active site, is essential to its function as a catalyst. Like other proteins, enzymes denature, or lose their original conformations, above a certain temperature.
What is the functional significance of the active site?
Active site is the site on the enzyme to which a substrate will latch and form an Enzyme – Substrate Complex (ESC)
It is structured to facilitate the binding of its substrate
How does the lock-and-key model explain enzyme-substrate specificity?
Both the enzyme and substrates have fixed shapes.
These specific shapes mean any alteration in any level of the structure will affect whether the Enzyme can form a complex
In this model, the active site is the “lock” and its complementary substrate is the “key.”
What is Denaturation
Denaturation is the breaking of Hydrogen bonds which hold Proteins together.
High Temperatures and Extreme changes in PH Level (High/Low) affect iconic bonding and render the enzyme obsolete
What does Insulin Do
Decreases blood glucose levels
Promotes Storage of Glucose
Decreases energy production from other sources Glycogen, fat and Protein metabolism
How is Insulin Made
- MRNA Moves toward RER
- Creates Pre pro-insulin
- Pre part (hydrophobic) so removed
- Parcelled into vesicle in Golgi Body
- Pro Insulin matures in Golgi Body where it becomes Insulin
- Leaves Golgi to sit on Beta cell in cell membrane
What is the main stimulator for insulin secretion
Glucose
Describe the process of the release of Insulin
- Glucose is taken up by Beta Cells and passes through GLUT 2 (Glucose Transporter)
- Glucokinase acts on Glucose molecule to start Glycolysis and Phosphorylation
- This Produces ATP
- ATP closes Potassium channel and therefore changes the charge of the cell membrane (Depolarisation)
- The change in charge opens calcium channel
- Influx of Calcium ions triggers insulin granule translocation (release of Insulin)
Explain the Biological action of Insulin
- Insulin binds to receptor on surface of a cell e.g., Fat Cell (the Alpha Subunit) (outside the cell)
- Passes through to the Beta Subunit (inside Cell) into the main body of the cell
- Releasing Insulin responsive substrate (insulin broken down into tiny pieces)
- Insulin then acts on GLUT 4 in the cytoplasm of the cell
- It moves the GLUT4 to the membrane of the cell opening up a channel for glucose to enter the bloodstream
