Exam 2: Ch 7 Flashcards
(46 cards)
Metabolism
the complex network of chemical reactions that occur within a cell to convert nutrients into energy, build new molecules, and perform essential functions for life, including breakdown of waste products.
Anabolism
the metabolic process where cells build complex molecules, like proteins and carbs, from smaller simpler molecules, requiring energy (usually from ATP) to facilitate this construction and support cell growth and repair. Anabolism is essentially the “building-up” aspect of metabolism.
Catabolism
opposite of anabolism, is the set of metabolic pathways that break down large complex molecules like carbohydrates, proteins and lipids into smaller sub units, releasing energy in the process and storing it as ATP’s.
Define: metabolism, anabolism, catabolism. How are they similar and different?
Metabolism is the umbrella term for both anabolism and catabolism functions. Anabolism deals with building molecules whereas catabolism deals with breaking down molecules, both requiring ATP’s as energy interchangably. .
Know the 8 statements that guide the study of metabolic processes
Every cell acquires nutrients
Metabolism requires energy from light or from catabolism of nutrients.
Energy is stored in the form of ATP (Adenosine Triphosphate) or GTP (Guanosine Triphosphate) a less common form.
Cells catabolize nutrients to form precursor metabolites- small molecules such as amino acids and sugars.
Metabolites, ATP’s and enzymes are all precursors for anabolic reactions.
These anabolic reactions form macromolecules- like complex proteins, carbohydrates, lipids and nucleic acids.
Cells grow when they are able to anobilize and form these macromolecules.
Cells are then able to reproduce once they have doubled in size from the nutrients.
Oxidation and Reduction Reactions:
where electrons are transferred between molecules, often facilitated by enzymes, to breakdown larger compounds into smaller ones or vice versa.
ATP Production and Energy Storage:
the build-up and break-down of molecules facilitated by enzymes, leads to the production of energy in the form of ATP for cellular processes. The ATP Cycle is when ATP is broken down into ADP(Adenosine Diphosphate) and inorganic phosphate, releasing energy that can be used by the cell.
Enzymatic reactions in Metabolism:
Enzymes are proteins that speed up chemical reactions in the body. Each enzyme is designed to catalyze a specific type of reaction.
Catabolic pathways
release energy by breaking down complex molecules to simpler compounds. This energy is stored in organic molecules until it needs to do work in the cell, (Initally require ATP, but they result in a net gain of ATP)
Anabolic pathways:
consume energy to build complicated molecules from simpler compounds. The energy released by catabolic pathways is used to drive anabolic pathways.(Uses ATPs)
Exergonic reactions
is an net release of free energy and delta G is negative. Released free energy—> Perform Work. Delta G= -686 kcal/mol
Endergonic reactions:
absorbs free energy from its surroundings and delta G is positive. Photosynthesis is steeply endergonic, powered by the absorption of light energy. Delta G= +686 kcal/mol
Closed System:
is a scenario where a cell does not exchange any matter with its environment, meaning it can neither take in nutrients nore release waste products, A cell that has reached metabolic equilibrium has died, no exchange of nutrients,
Open System
cell maintains disequilibrium because they are open with a constant flow of material in and out of the cell. A healthy living cell will have an open system with a metabolic disequilibrium.
How many reactions can occur in one catabolic process?
A catabolic process in a cell releases free energy in a series of reactions, not in a single step. Multi-step depending on the specific molecule being broken down.
Describe oxidation-reduction reaction, how are electrons transferred in this reaction? What are oxidizer vs. reducer? Are electron carriers the oxidizers or the reducers? Name 3 major electron carriers in the cell?
Oxidation-reduction reaction: is the transfer of electrons from one molecule that donates electron to another molecule that accepts electrons. Cells use electron carrier molecules to carry electrons.
Oxidizer: losses the electrons relsulting in an increase in the oxidation number.
Reducer: gains the electrons resulting in a decrease in the oxidation number.
The electron carriers are the reducers.
Three electron carriers:
Nicotinamide Adenine Dinucleotide(NAD+)—>NADH
Nicotinamide Adenine Dinucleotide Phosphate(NADP+)—>NADPH
Flavin Adenine Dinucleotide (FAD)—>FADH2
Describe phosphorylation reaction to make ADP and ATP from AMP. Where does the energy used in anabolic pathway come from?
Phosphorylation: organic phosphate is added to substrate or the process of adding a phosphate group to a protein molecule.
Energy released from nutrients can be stored in high-energy phosphate bonds of ATP via phosphorylation of ADP.
Anabolic pathways use some energy of ATP by breaking a phosphate bond, the energy for building complex molecules in anabolism comes from then breakdown of other molecules in catabolism.
What are the roles of enzymes in metabolism?
Enzymes are organic catalysts that increase the likelihood of reactions. Specific for a substrate, aid in the building-up an breaking-down of molecules. Enzymes are proteins.
Describe six enzyme categories (names and functions)
Hydrolases: removes hydrogens
Isomerases: rearrange atoms
Ligases or Polymerase: joins molecules
Lyases: breaking chemical bonds
Transferases- transfer functional groups
Oxidoreductases
Components of a holoenzyme.
A holoenzyme is a fully functional enzyme that consists of an apoenzyme and its cofactors making it active and ready to perform its biological functions. Ribosomes are an example of a holoenzyme.
Apoenzyme: protein portions that are inactive if not bound to cofactors.
Cofactors: the non protein part of the holoenzyme. Co factors can be metal ions or organic molecules called coenzymes. They attach to the holoenzyme.
Are enzymes always proteins?
Yes, enzymes are almost always proteins,
How do enzymes affect the activation energy requirement in a reaction?
Enzymes significantly lower the activation energy required for a chemical reaction to occur, essentially making it easier for the reaction to proceed by providing an alternative pathway with lower energy barrier, thus speeding up the reaction rate.
What is “enzyme turnover number”? What can affect enzyme turnover number? Be able to interpret an enzyme’s activity on an activity chart and deduce the effects of temperature or pH or substrate concentration or inhibitors. What does “saturation point” mean?
The number of substrate molecules converted into a product by an enzyme in a unit of time when the enzyme is fully saturated with substrate. 1-10,000 molecules/sec
Temperature, pH levels, inhibitors and substrate concentrations can all affect enzyme turnover.
Keep in mind that denaturation of an enzyme is when an enzyme becomes disfigured and dysfunctional due to high levels of pH, temp etc.
Saturation Point: refers to the substrate concentration at which all active sites on an enzyme molecule are occupied by substrate molecules.
Types of enzyme’s inhibitors? How do they inhibit enzyme’s activities?
Inhibitors: are substances that block an enzymes active site to prevent activity but do not denature the enzyme.
