Intermediary Metabolism 1 Flashcards
Stability, balance, or equilibrium within a cell or body.
Homeostasis
The level or point at which a variable physiological state tends to stabilize.
Set point
Self-adjusting mechanism by the internal system
Feedback regulation
Two types of feedback regulation
Positive and negative feedback regulation
What are the three mechanisms of regulation?
Osmoregulation, Thermoregulation, and chemical regulation
What is positive feedback regulation?
Regulation that acts to speed up the direction of change.
What is negative feedback regulation?
Regulation that acts to reverse the direction of change to maintain the set point.
Which feedback regulation is the most common?
Negative feedback regulation
Name and explain the 3 types of osmoregulation solutions
1.Hypertonic solution- The solution outside the cell is more concentrated than the inside of the cell. Water will move out of the cell by osmosis, causing it to shrink.
- Isotonic solution- The solution inside the cell has the same concentration as the outside of the cell. Water will move in and out of the cell at an equal rate.
- Hypotonic solution- The solution outside of the cell has a lower concentration than the inside of the cell. Water will move into the cell by osmosis, sometimes causing it to burst.
Name the six classes of enzymes.
1.Oxidoreductases
2. Transferases
3.Hydrolases
4.Lyases
5.Isomerases
6.Ligases
Explain what oxidoreductases catalyze
They catalyze oxidation-reduction reactions, which involves the loss or gain of protons.
Explain what reactions do transferases catalyze
They catalyze the transfer of a C-, N-, or P- containing groups.
Explain which reactions do hydrolases catalyze
Catalyze cleavage of bonds by addition of water.
What do lyases catalyze
Catalyze the cleavage of C-C, C-S and certain C-N bonds.
Which reactions do Isomerases catalyze?
Catalyze the racemization of optical or geometric isomers.
Which reactions do ligases catalyze?
Catalyze the formation of bonds between C and O, S, N coupled to hydrolysis of high energy phosphates.
Name 4 catalytic strategies
Covalent catalysis
Acid-base reactions
Catalysis by approximating
Metal ion catalysis
Briefly explain the covalent catalysis
In covalent catalysis, the enzymes covalently bond to the substrate as the first step.
The active sites contain a reactive group, that forms a covalent bond with the substrate.
Then, the enzyme goes through a mechanism, eventually breaking down the substrate and reforming itself.
What occurs in acid-base reactions of enzyme-substrate?
The enzymes generally use a molecule other than water to donate or accept protons as a nucleophile.
Briefly explain catalysis by approximation
The close proximity of two substrates can increase the rate of reaction between the two.
Generally, when two molecules combine to become one entropy decreases.
An enzyme that brings the two molecules together decreases the entropy.
This increase in rate is similar to increasing the concentration of the reactants.
Briefly explain metal ion catalysis
Metal ions can directly facilitate the formation of bonds.
They are electrophilic and can also act to stabilize the charges on the intermediates in the reaction.
What are holoenzymes, and differentiate between holoenzymes and apoenzymes.
Holoenzymes are the enzymes that require molecules other than proteins for enzymic activity.
Holoenzyme- is active with its nonprotein compenent.
Apoenzyme- is inactive without its nonprotein component.
Name three factors that affect enzyme function
-Substrate concentration
-Temperature
-pH
By definition, what is Km?
Km is the substrate concentration at which the velocity is half of the maximum velocity.
