Lecture 8 Bacterial Metabolism Flashcards
(77 cards)
Sum of all the biochemical reactions occurring within the living cell required for energy generation
Use of energy to synthesize cell materials from small molecules of the environment
Food –Catabolic pathways-> Energy, cellular building blocks, heat –Anabolic pathways-> Macromolecules
Metabolism
Bacterial Nutrition
_ - substances used in biosynthesis and energy production
- bacteria require energy and nutrients to build proteins and structural membranes and drive biochemical processes
- bacteria require sources of C, N, P, Fe and a large number of other molecules
Nutrition
Bacterial Nutrition
- _, _, _: highest quantities
- nutritional requirements for bacteria can be grouped according to the _, _, and _ source
- C, N, H2O
- Carbon, Electron, Energy Sources
Energy Source
_ - organisms that capture protons in order to acquire energy, energy source is mainly sunlight, classified as photoautotrophs and photoheterotrophs
_ - organisms which obtain energy by oxidizing electron donor, energy source is oxidizing energy of chemical compounds, classified as chemoorganotrophs and chemolithotrophs
Energy Source
- Phototrophs
- Chemotrophs
Electron Source
_ - organisms that can use reduced inorganic compounds as electron donors
_ - organisms that can use organic compounds as electron donors
Electron Source
- Lithotrophs
- Organotrophs
Electron Source
Lithotrophs and Organotrophs
_ - gain energy from light, use reduced inorganic compounds such as H2S as source of electrons (e.g. Chromatium okeinii)
_ - gain energy from light and use organic compounds such as Succinate as source ofelectrons (e.g. Rhodospirillum)
Photolithotrophs
Photoorganotrophs
Electron Source
Lithotrophs and Organotrophs
_ - gain energy from reduced inorganic compounds such as NH3 as source of electron (e.g. Nitrosomonas)
_ - gain energy from organic compounds such as glucose and amino acids as source of electrons (e.g. Pseudomonas pseudoflora)
- some bacteria can live either _ or _ like Pseudomonas pseudoflora as they can use either glucose or H2S as electron source
Chemolithotrophs
Chemoorganotrophs
Carbon Source
_ - producers, photosynthetic, use CO2 and H2O, sunlight as energy, make their own food
_ - require preformed food, digestive and absorptive, most microbes
_ - unique metabolism, use chemical energy from inorganic molecules, S and Fe
Autotroph
Heterotroph
Chemoautotroph
All cells need to accomplish 2 fundamental tasks:
- Synthesize new parts - cell walls, membranes, ribosomes, nucleic acids
- Harvest energy to power reactions
Ability to do work required to drive various biosynthetic/chemical reactions to do mechanical work
Construction of the structural parts of the cell, synthesis, repair of damage and maintenance, growth and multiplication, accumulation of nutrients and excretion of waste products, motility
Energy
Two Components of Metabolism
_ - degradation
- breaking down complex molecules into simple ones
- process that breaks down compound to release energy
- generation of energy (ATP)
- smth -> energy
Catabolism
Two Components of Metabolism
_ - biosynthesis
- building complex molecules from simple ones
- assemble subunits of macromolecules
- use of energy (ATP)
- energy -> smth
Anabolism
Two Components of Metabolism
_ + _ -> _
These 2 processes are intimately linked with each other
Catabolism + Anabolism -> Metabolism
Metabolic Pathways
A. _ - starting compound -> intermediatea ->intermediateb -> end product
B. _ - starting compound -> intermediatea1, intermediatea2 -> end product1, end product2
C. _ - starting compound -> intermediatea -> intermediateb -> intermediatec -> end product, intermediated
Metabolic Pathways
A. Linear
B. Branched
C. Cyclical
_ - substance on which an enzyme acts
_ - biological catalyst, speed up conversion of a substrate into a product
- in between _ and _ is _ _ -> - _
- Substrate
- Enzyme
- Active Site, Enzyme-Substrate Complex
Increases the rate of chemical reactions
Do not become part of the products
Are not consumed in the process
Do not create a reaction
Are highly specific for substrates
Enzymes
Sructures of Enzymes
_ _ - protein alone
_ _ (holoenzymes) - composed of protein and nonprotein parts
- _ - protein portion of conjugated enzyme (holoenzyme)
- _ - either organic molecules (coenzymes) or inorganic elements (metal ions, metallic cofactors)
Simple Enzymes
Conjugated Enzymes
- Apoenzymes
- Cofactors
Structures of Enzymes
Some Coenzymes and their Function
Coenzyme | Vitamin from which it is derived | Substance Transferred | Example of Use
Coenzyme A, Flavin adenine dinucleotide, Nicotinamide adenine dinucleotide, Pyridoxal phosphate, Tetrahydrofolate, Thiamin pyrophosphate
Coenzyme A - carries the acetyl group that enters TCA cycle
Flavin adenine dinucleotide - carrier of reducing power
Nicotinamide adenine dinucleotide - carrier of reducing power
Pyridoxal phosphate - transfers amino groups in amino acid synthesis
Tetrahydrofolate - 1-carbon donor in nucleotide synthesis
Thiamin pyrophosphate - helps remove CO2 from pyruvate in the transition step
Substrate-Enzyme Interaction
- a temporary enzyme-substrate union must occur at the active site:
- fit is so specific that it is described as a --_ fit
- bond formed between substrate and enzyme are _ and _ _
- once E-S complex has formed, appropriate reaction occurs on the substrate, often with aid of a cofactor
- product is formed
- enzyme is free to interact with another substrate
- lock-and-key fit
- weak and easily reversible bond
Classification of Enzymes
Enzymes are classified and named according to characteristics such as _ _ _, _ _ , and _
- prefix or stem word derived from certain characteristic, usually the substrate acted upon or type of reaction catalyzed
- ending -
- _ classes based on biochemical action
- site of action, type of action, substrate
- -ase
- 6 classes
Classification of Enzymes
Enzyme Classification based on Reaction Types
Class | Type of Reaction Catalyzed | Example
HILLOT
Hydrolase - Lipase - breaks down lipid molecules
Isomerase - Phosphoglucoisomerase - converts g-6-p into f-6-p during glycolysis
Ligase or polymerase - Acetyl-CoA synthetatse - combines acetate and coenzyme A to form acetyl-CoA for Krebs cycle
Lyase - f1,6-bp aldolase - oxidizes lactic acid to form pyruvic acid during fermentation
Oxidoreductase - lactic acid dehydrogenase - oxidzes lactic acid to form pyruvic acid during fermentation
Transferase - hexokinase - transfers phosphate from ATP to glucose in 1st step of glycolysis
Enzyme Regulation
Activity of enzymes influenced by cell’s environment
- _, _, _
Temperature, pH, osmotic pressure
Enzyme Regulation
_ - weak bonds that maintain the native shape of the apoenzyme are broken
- enzyme’s shape is disrupted
- prevents the substrate from attaching to the active site
- heat above 40 degrees C - active site of enzyme changes shape and can no longer bind to substrate, it has been _
Denaturation
Controls on the Actions of Enzymes
_ _ - inhibits enzyme activity by supplying a molecule
- “mimic” occupies the active site, preventing actual substrate from binding
_ _ - enzymes have 2 binding sites: _ site and _ site
- molecules bind to regulatory site
- slows down enzymatic activity once a certain concentration of product is reached
Competitive inhibition
Noncompetitive inhibition
- active site and regulatory site
