Unit 5 - Cell Energy Flow Flashcards
What are the two components (“steps”) of metabolism?
Catabolism = breakdown reactions Anabolism = synthesis reactions
What is metabolism?
The total of all chemical reactions that take place within a cell
What is the difference between Kinetic Energy and Potential Energy?
KE = energy in motion PE = stored energy
What are the two laws of thermodynamics?
- Energy cannot be created or destroyed, only converted from one form to another
- In any chemical reaction there will always be some energy which is lost in the form of heat.
What process is an example of biological entropy?
Cellular respiration
What process is an example of biological enthalpy?
Photosynthesis
What is a metabolic pathway?
A stepwise sequence of reactions in cells, with specific enzymes catalytic each step
What are 2 benefits of metabolic pathways?
- Conservation of energy
2. Many products can be produced from a single original substance
What is a catabolic pathway?
The breakdown of large biological molecules, usually with the release of energy (I.e. Cellular respiration)
What is an anabolic pathway?
Construction of biological molecules using energy (I.e. Photosynthesis)
Give at least 4 characteristics of an enzyme
- Catalysts for biological reactions
- Most are proteins
- Lower activation energy
- Increase rate of reaction
- Activity lost if denatured
- Are not used up in reaction
What 2 parts does an enzyme consist of?
- Apoenzyme
2. Coenzyme
What is an apoenzyme and what does it do?
It’s a protein that acts as the active site of the enzyme. It is also the functional unit of the enzyme and is created in the cell
What is a coenzyme and what does it do?
It’s a non-protein that activates the apoenzyme, and is obtained through the diet (not made in cells). It’s usually a vitamin and it participates in the reaction by contributing/accepting atoms or electrons
Describe the Lock + Key Model of enzyme action
- Enzyme binds to a substrate in the active site (only certain substrates can fit in the active site)
- Amino Acid R-Groups in the active site help the substrate bind
- Enzyme-substrate complex is formed
- Substrate reacts to form product
- Product is released (enzyme is not used up)
What is the Induced-Fit Model of Enzyme Action and how is it different from the Lock and Key Model?
The Induced Fit Model uses enzymes that are flexible, not rigid. The enzyme and the active site adjust their shape to bind to the substrate. The Induced Fit Model also increases the range of substrate specificity
What are the 4 factors that affect Enzyme Action?
- Temperature
- Substrate Concentration
- pH level
- Radiation
How does temperature affect enzyme action?
- Little activity at low temperature
- Rate increases at higher temperature
- Most activate at optimum temperature (37deg for humans)
- If temperature is too high, activity is lost with denaturation.
How does substrate concentration affect enzyme action?
- ^concentration increases rate of reaction
- Max activity teaches when all of enzyme is in use
- After saturation point, reactions remains flat because increasing amounts of substrate must wait before they can fit with their enzyme (enzyme concentration is constant)
How does pH affect enzyme action?
- Max activity at optimum pH
- R-groups of amino acids have proper charge
- Most lose activity in low/high pH
How does radiation affect enzyme action?
It denatures the enzyme and prevents enzyme action t
What do enzyme inhibitors do?
- Cause a loss of catalytic activity
- Change the protein structure of an enzyme
- May be competitive or non-competitive
- Some effects are irreversible
What do competitive inhibitors do?
- Has a structure similar to substrate
- Occupies the active site
- Competes with substrate for active site
- Has effect reversed by increasing substrate concentration
What’s a non-competitive inhibitor and what does it do?
- Does not have structure like substrate
- Bonds to the enzyme but not the active site
- Changes shape of enzyme and active site
- Substrate cannot fit altered active site
- No reaction occurs
- Effect is not reversed by adding more substrate
What is an example of a non-competitive substrate?
Heavy metals, drugs
What is thyroxin?
A modified amino acid contains iodine that is produced in the thyroid gland
What does thyroxin do?
Increase the metabolic rate by:
- Increasing synthesis of enzymes
- Increasing heart rate
- Increasing breathing rate
It also creates more body heat
