Module 2 Flashcards
What is Cellular Metabolism?
A controlled set of biochemical reactions that occur in living organisms in order to maintain life
What is the primary function of enzymes, and how are they regulated?
Enzymes speed up chemical reactions by lowering the activation energy. The enzyme is not consumed during the reaction and can be used repeatedly by a cofactor. Cofactors can regualte enzymes, there are times when cofactors must be present for the enzyme to work.
What is Catabolism?
The process of breaking down larger molecules into useful energy sources
What is Anabolism?
The building up or biosynthesis of macromolecules from smaller molecular units into larger complexes, most often associated with cellular growth and repair
ATP has the energy to ___ energy
Donate
ADP has the capacity to ___ energy
Accept
Chemotrophs can be subdivided into what 2 additional subgroups?
Chemotrophs acquire energy from preformed chemicals found in the environment such as organotrophs or lithotrophs
What are Organotrophs?
A chemical that removes electrons from organic molecules such as glucose
What are Lithotrophs?
A chemical that removes electrons from inorganic molecules
Chemotrophs utilize which form of phosphorylation?
- Oxidative phosphorylation; utilizes the energy released by the chemical oxidation of nutrients to reform ATP
- May also accept substrate level phosphorylation
What are the 3 distinct stages in the catabolism of glucose?
- Glycolysis : yields 2 molecules of ATP
- Fermentation (or respiration) : 2 additional molecules of ATP produced (resp.)
- Electron Transport Chain (ETC) : produces 34 ATP via an oxidative phosphorylation event at mitochondrial membrane
What are the Reactants of Glycolysis?
- Glucose
- 2 NAD+
- ATP
What are Reactants?
Any molecules present and involved at the beginning of a specific chemical reaction, located to the left of the arrow
What are the 2 main strategies for replenishing cellular concentrations of NAD+, and when these strategies be utilized?
- Fermentation and Respiration are the 2 strategies used by the cell to convert NADH back to NAD+
- Fermentation occurs in the absence of oxygen (anaerobic conditions) while Respiration occurs under aerobic conditions (presence of oxygen)
- Respiration is more efficient than fermentation
How are the TCA and ETC related?
The end products of the Kreb’s (TCA) are used to fuel the ETC. The Kreb’s cycle produces an abundance of reduced electron carriers (NADH and FADH2), it fuels the ETC. As the electrons are transferred from NADH/FADH2 to terminal electron acceptors a proton motor force is generated, ATP synthase is activated and up to 34 molecules of ATP can be produced.
In the absence of sugars, are entirely different metabolic pathways used to process alternative sugar sources (fructose or lactose)?
No. Additional enzymatic steps are simply required at the beginning of catabolism to convert complex sugars into usable forms of either glucose or a glucose intermediate (glucose-6-phosphate).
Proteases are used to catabolize what?
Proteases are used to breakdown proteins
Lipases are used to catabolize what?
Lipases are used to breakdown lipids
Excluding sugars, what are the other sources of energy? Which is highest in energy?
Carbohydrates, proteins, and lipids can all serve as potential energy sources in the absence of sugar. Lipids are rich in energy, often having several reduced carbon molecules (high in hydrogen content) that can be used in both the TCA and ETC cycles.
In what organelle does photosynthesis take place?
Occurs in the chloroplasts. Chloroplasts are double-membrane enclosed organelles. Each chloroplast contains the green photosynthetic pigment chlorophyll.
What is Photosynthesis?
Where does it occur?
The process of capturing sunlight and converting it into usable energy source, occurring in the chloroplasts
In phosphorylation, the light reactions always occur where?
(what is the main function)
The process of converting light energy into chemical energy (photophosphorylation) always occurs in the membrane. Similar to the ETC, one of its main functions is to generate a proton concentration gradient to generate ATP.
What are the byproducts of light reactions used for in dark reactions?
The ATP and NADPH produced via light reactions are used in dark reactions to convert carbon dioxide and water into organic carbon compounds as well as useful carbohydrates (a process called carbon fixation)
What determines the specificity of an enzyme?
(what is the structure influenced by)
Heavily influenced by its active site; a unique chemical structure bound only by select target molecules. The structure is influenced by the amino acid composition of the protein as this in turn influences the fold, shape, and ‘appearance’ of the enzyme. The active site provides a specificity (like a lock) that only specific target proteins can bind
What are Enzymes?
A protein that catalyzes a specific chemical reaction, the function of an enzyme is dependent on its structure
What is Catalysis?
Acceleration of a reaction by making it more energetically favorable, lowers the activation energy
What is a Cofactor?
- Metal ions that activate or enhance enzyme activity
>Calcium ion, Ca2+
>Zinc ion, Zn2+
What is a Substrate?
The target of the enzyme
What is an Active Site?
The component of the enzyme that binds the substrate and alters it producing a product, an induced fit
What is Specificity?
Selectiveness of enzyme for a specific substrate
Amylase is used to catabolize what?
Amylase is used to breakdown starch
Catalase is used to catabolize what?
Catalase is used to breakdown H2O2 into water and oxygen
What are Hydrolases?
An enzyme used to catalyze hydrolysis chemical bonds with the addition of water, resulting in the division of a larger molecule into smaller molecules
A-B +H2O -> A-OH +B-H
What are Isomerases?
An enzyme used to catalyze rearrangement of bonds within the molecule to produce an isomer
A-B -> B-A
What are Ligases?
Covalent bonds that join 2 molecules together
A+B -> A-B
What are Lyases?
- An enzyme that cleave (split) bonds other than using hydrolysis or oxidation
A-B -> A+B
What are Oxidoreductases
An enzyme that transfer electrons from reductant to the oxidant
A:+B -> A+B:
What are Transferases?
An enzyme that transfers a functional group
A-b+C -> A+C-b
What is an Oxidation-Reduction Reaction?
When an electron is transferred, electrons carry energy
What is an Electron Acceptor?
- The gain of electrons reducing its overall charge to be more negative
- Molecules that accept electrons are reduced
What is an Electron Donator?
The loss of electrons mostly to oxygen
Molecules that donate electron are oxidized
What does OIL RIG stand for?
Oxidation is Loss, Reduction Is Gain
What is Adenosine Triphosphate (ATP)?
- An organic compound that provides energy to drive and support many processes in cells
- An activated carrier, the most widely used form of energy in the cell
- Generated by a phosphorylation reaction
What is Photophosphorylation?
When light energy is used to power the formation of ATP from ADP
What is Substrate-Level Phosphorylation?
When the phosphoryl (PO3) group of a chemical compound is transferred and donated directly to ADP. The chemical compound losing the phosphate group is referred to as the phosphorylated reactive intermediate
What is Oxidative Phosphorylation?
- When the energy is released by the chemical oxidation of nutrients to reform ATP
- This is the process that is used by chemotrophs
- This process occurs in the mitochondria of eukaryotic cells and is highly efficient
ATP Production Processes
- Photophosphorylation
- Substrate-Level Phosphorylation
- Oxidative Phosphorylation
Requirements for Generating Energy?
All cells need a source of carbon, energy, and electrons or hydrogen atoms
What are Phototrophs?
A microorganism that acquire energy from photons of light to generate ATP
What are Chemotrophs?
A microorganism that acquire energy from preformed chemicals found in the environment
What is a Heterotroph?
A microorganism that derives its carbon from organic molecules
What is an Autotroph?
Microorganisms that derive their carbon from inorganic molecules
What is Glycolysis?
(splitting a sugar)
The breakdown of a single molecule of glucose
Reactants of Glycolysis
(energy investment phase)
Glucose + (2NAD+) + [2ADP+2Pi] : glucose + 2 nicotinamide adenine dinucleotide + ATP
Products of Glycolysis
(energy payoff phase)
2 Pyruvate + NADH + 2ATP + (H+)
Pyruvate moves on to citric acid cycle
First Step of Glycolysis?
- Phosphorylation of glucose, glucose-6-phosphate
>Prevent glucose from diffusing out of the cell
What is Fermentation?
- An anaerobic process that converts NADH back to NAD+ and pyruvate is converted to a waste byproduct (as lactic acid or ethanol) to be eliminated
- Yields less energy
- Recycles NAD+, does not produce additional ATP
Tricarboxylic Acid Cycle (TCA)
(Citric Acid Cycle or Kreb’s Cycle)
- An intermediate step that converts pyruvate into Acetyl Coenzyme A, which enters the ETC by activated carriers NADH & FADH2
- Produces: 2 ATP, 6 NADH, 2 FADH2
Electron Transport Chain (ETC)
Can be aerobically or anaerobically. Electrons are transfered from NADH/FADH2 to terminal electron acceptors in the mitochondria. Electrons are passed down a chain of electron acceptors to be pumped out of the membrane. Causes a strong differential across mitochondrial membrane, which forms proton motive force.
Where is ETC Located?
Plasma membrane of prokaryotic organism
Protein Catabolism
Provides energy, nitrogen, and sulfur
Deamination
Removal of amino group
Lipid Catabolism
Provides substrates, activated carriers, and ATP
Photosynthesis
The process of capturing sunlight and converting it into ATP & NADPH, occurs in the chloroplasts
Chloroplasts
Double membrane-enclosed organelles specific to algae & plants
House the photosynthetic pigment chlorophyll
The Calvin Cycle
The dark reaction, the ability of a microorganism to use the ATP & NADPH generated in the light reaction to convert dioxide and water into organic carbon compounds and useful carbohydrates
The Calvin Cycle Equation
6 CO2 + 18 ATP + 12 NADPH + 12 H2O -> C6H12O6 + 18 ADP + 12 NADP+
