Metabolism Chapter Flashcards
Metabolism
Chemical reactions that organisms use to break down substances to release energy and reactions that use the released energy to build new substances.
Anabolic metabolism
Build new substances using energy and molecules
Catabolic metabolism
Breaks down substances to release energy
Other definition of metabolism
All of the anabolic and catabolic chemical reactions in a cell
What must something contain to be considered organic?
Carbon and hydrogen
What are the phases of cellular respiration?
Glycolysis
Krebs cycle
Electron transport chain
What is ATP?
Adenosine Tri-phosphate
How to catabolic reactions recharge ADP to ATP?
They use energy extracted from nutrients.
What kind of phosphorylation are glycolysis and the Krebs cycle?
Substrate level phosphorylation
What kind of phosphorylation is the electron transport chain?
Oxidative phosphorylation
Amphibolic pathways
Used for both breaking down and building substances
What are the functions of enzymes?
Catalyst for chemical reactions
Lower the energy of activation
What are enzymes?
Protein catalysts that help chemical reactions occur under cellular conditions.
What is a catalyst?
Something that is only needed in small amounts to make a reaction happen faster, or increases the reaction rate.
Are catalysts consumed or permanently changed by a reaction?
No
Do enzymes facilitate chemically impossible reaction?
No, they help chemical reactions occur under physiological conditions within a time frame conductive to life.
Chemical reactions involve what?
The making or breaking of chemical bonds.
What is collision theory?
Atoms and molecules are constantly moving and often hit one another. The energy transferred during these collisions can disturb the electron structures of atoms and molecules enough to make or break chemical bonds.
Where to substrates bind on the enzyme?
Specifically to the active sites.
What is the lock-and-key model
Stayed that an enzyme is like a lock that can only be opened by a specific key: the substrate. The keyhole is the active site.
What is the enzyme’s active site?
The site where the substrate and enzyme interact to generate a chemical reaction.
T or F: the lock-and-key model is outdated.
True
What is the model we now use to describe how substrates and enzymes interact in the active site?
Induced fit model.
Describe the induced fit model
Enzymes and substrates are somewhat flexible, both can change shape slightly upon interacting. This allows enzymes to slightly mold and position the substrate in a way that will encourage reaction.
What is an enzyme-substrate complex?
When an enzyme and a substrate come together. Here the activation energy required to start a chemical reaction and proper positioning of the reactants are achieved so the chemical reaction can occur. Also stabilizes the transition state of the reaction.
What is a transition state?
A brief yet critical point when reactants are chemically becoming products, but the reaction is not yet completed.
Stabilizing a transition state does what?
Facilitates chemical reactions.
How do enzymes lower activation energy?
By the combined effects of efficiently branding reactants together and stabilizing transition states.
General mechanism of enzyme-substrate interaction steps
- Enzyme is available with empty active site
- Substrate bonds to active site, forming an enzyme-substrate complex
- Substrate is converted to products after going through a transitional state
- Products are released and enzyme is again available
What are cofactors?
Additional components that some enzymes need to function.
What is an enzyme without it’s necessary cofactor called?
An apoenzyme. It is inactive.
What is an apoenzyme
An enzyme that is without it’s necessary cofactor and is thus inactive.
What is a holoenzyme?
The functional form of th enzyme that includes the enzyme and any necessary cofactors.
What are examples of inorganic cofactors that may help catalyze a reaction by forming a bridge between the enzyme and a substrate?
Iron, zinc, magnesium, and claim ions.
Organic cofactors are typically called
Coenzymes.
Coenzymes:
Nonprotein factors anchored to the enzyme they assist. Often vitamins or are made from vitamins.
What are common electron-carrier coenzymes?
NAD+, NADP+, FMN, and FAD
What are electron-carrier enzymes?
Coenzymes that collect electrons from one reaction and shuttle them to other reactions in the cell.
What is phosphorylation?
The addition of a phosphate onto an ADP molecule through catabolic reactions.
What is responsible for releasing energy to fuel anabolic reactions?
Phosphate
What is another name for anabolic reactions?
Biosynthetic reactions
What do anabolic reactions use to build molecules?
Energy
What happens if a cell loses its ability to make ATP?
It will die.
How is ATP made?
By catabolic reactions. Provides energy for anabolic reactions.
Cells break down nutrients to get:
ATP
Where do organic molecules such as proteins, lipids, and carbohydrates store energy?
In their bonds.
What is ATP made up of?
Adenine, ribose, and three phosphate groups.
What happens when the last phosphor group from ATP is removed dephosphorylation?
Energy and adenosine diphosphate are released (ADP)
Adenosine diphosphate contains how many phosphate groups?
Two
How can a cell get more ATP?
By adding a phosphate group to ADP via phosphorylation
What is the ATP-ADP Cycle?
The adding and removing of the terminal phosphate group.
Where does the energy to recharge ADP back to ATP come from?
Catabolic reactions.
What can the energy released when ATP becomes ADP do?
Fuel anabolic reactions
What happens in an oxidation reaction?
An atom or molecule loses electrons.
What happens in a reduction reaction?
An atom or molecule gains electrons.
How are oxidation-reduction reactions coupled?
When an atom or molecule loses an electron (is oxidized) another entity absorbs that electron and is reduced.
What are oxidation-reduction reactions referred to?
Redox reactions.
What are redox reactions?
Oxidation-reduction reactions.
What is a common oxidizing agent in biochemical reactions? What is a common reducing agent?
Oxygen is oxidizing and hydrogen is reducing.
How do cells harvest energy from nutrients?
By oxidizing them: stripping electrons from them.
Molecules that contain abundant hydrocarbon bonds are
Highly reduced.
Examples of highly reduced molecules that cells can extract energy from using redox reactions:
Sugars and fats.
Why do proteins make less ATP than carbohydrates and fats?
Because they are less reduced.
Enzyme names usually end in what suffix?
-ase
What are the six different classes that enzymes fall into?
Oxidoreductase Transferase Hydrolase Lyase Isomerase Ligase
What are the classes enzymes fall under based on?
The reactions they catalyze