Chapter 5: Metabolism Flashcards
Metabolism
Sum of chemical reactions in an organism
Anabolism
Energy-using process of synthesize macromolecules that make up the cell
Catabolism
Energy-releasing process by oxidation of molecules
Enzymes
-proteins
-not altered or used up in chemical reactions
-specificity is a function of their active site
Transferase
Transfer function groups
Hydrolase
Hydrolysis
Lyase
Rem of atoms w/o hydrolysis
Isomerase
Rearrangement of atoms
Ligase
Joining of molecules, uses ATP
Components of a holoenzyme
Apoenzyme (protein portion), inactive + Cofactor (nonprotein portion), activator = Holoenzyme (whole enzyme), active
Factors influencing enzymes
High temp. (Works faster at first then changes shape) And high pH can denature enzymes
⬆️[substrate]➡️ ⬆️reaction rate until active sites are saturated (all the available binding spots on an enzyme molecule are occupied by substrate molecules, essentially reaching the maximum capacity of the enzyme to catalyze a reaction, so adding more substrate will not increase the reaction rate further)
Inhibitor: molecules that bind to an enzyme and prevent it from functioning
Activator: Molecules that can enhance enzyme activity by binding to the enzyme and changing its shape slightly
Aerobic respiration
1) glycolysis
2) transition of preparatory step
3) Krebs cycle (2 turns)
4)e- transport chain
38 ATP
Glycolysis
-The oxidation of glucose to pyruvate
-Produces 2 ATP and 2 NADH (coenzyme) from one glucose molecule
-Does not require oxygen
More ATP is formed than is consumed in this process
• Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH.
• Glucose is the original electron donor.
• The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compounds
Transition of preparatory step
-Pyruvic acid (from glycolysis) is oxidized
-Acetyl group attaches to CoA > Acetyl-CoA
-No ATP made in this step
-CoA> CO2
-NAD+>NADH
Krebs cycle
-2 turns
-2 ATP
-6 NADH
-2 FADH2
-4CO2
-Oxidation of Acetyl CoA produces NADH and FADH2
-E-’s are picked up by NAD+ and FAD for e- Transport Chain
e- transport chain
-E-’s are brought to the chain by NADH and FADH2
-A series of carrier molecules, are oxidized and reduced as e-’s are passed down the chain
-Energy released can be used to produce ATP
-34 ATP
Summary of respiration
-Aerobic respiration: the final e- acceptor in the ETC is molecular O2
-Anaerobic respiration: the final e- acceptor in the ETC is not O2
Anaerobic respiration
-Carried out by certain anaerobic bacteria (ex. clostridium)
-Amount of ATP varies; never as high as aerobic respiration
-Only part of the Kreb cycle operates
-Not all carrier in the ETC participates- why anaerobic respiration does not generate as much ATP
-final hydrogen (e-h) acceptor: usually inorganic substance but not O2
-type of phosphorylation used to generate ATP: substrate-level and oxidative
-ATP molecules produced per glucose molecule: variable 2-38
Fermentation
-Release of energy from oxidation of organic molecules
-Carried out by bacteria and yeast
-Uses organic molecules as final e- acceptor
-2NADH>2NAD+ (oxidized)
2ATP
-ethanol and CO2
-used to determine whether an organism can ferment a carb to produce lactic acid and gas
-ex. Mannitol fermentation by S. aureus
-aerobic or anaerobic
-final hydrogen (e-) acceptor : organic molecule
-type of phosphorylation used to generate ATP: substrate-level
Lactic acid fermentation
-Lactobacillus, Streptococcus, Bacillus
-End product: Lactic acid
Alcohol fermentation
Yeast
End product: ethanol and CO2
Fermentation of clostridium end product
Isopropyl alcohol
Describe the mechanism of enzymatic action
Substrate contacts region on the enzymes surface called the active site 2) a temporary intermediate compound forms, called an enzyme-substrate complex 3) substrate molecule is tranformed 4) the transformed substrate molecule is released because it no longer fits in active site - this is the product of the reaction 5) unchanged enzyme now free to react again
Describe the components of an enzyme
Enzymes are proteins (mostly globular), produced by living cells, that catalyze chemical reactions by lowering the activation energy.
Apoenzyme: protein portion
Cofactor: nonprotein component (inorganic or organic)
Coenzyme: organic cofactor
Holoenzyme: apoenzyme plus cofactor
Explain what is meant by oxidation-reduction.
Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
Describe the chemical reactions of glycolysis
1.The most common pathway for the oxidation of glucose is glycolysis. Pyruvic acid is the end-product. 2.Two ATP and two NADH molecules are produced from one glucose molecule
Explain the products of Krebs Cycle
1.Decarboxylation of pyruvic acid produces ONE CO2 molecule and ONE acetyl group. 2.Two-carbon acetyl groups are oxidized in the Krebs cycle. Electrons are picked up by NAD+ and FAD for the electron transport chain. 3.From one molecule of glucose, oxidation produces six molecules of NADH, two molecules of FADH2, and two molecules of ATP. 4. Decarboxylation produces six molecules of CO2.
Competitive inhibition
occurs when an inhibitor molecule directly competes with the substrate for binding to the enzyme’s active site
Non-competitive inhibition
happens when an inhibitor binds to a different site on the enzyme (allosteric site), altering the enzyme’s shape and indirectly preventing substrate binding, even if the substrate is already attached to the active site
Feedback inhibition
Excess end-product inhibits enzyme activity in a metabolic pathway
Ribozymes
Enzymatic RNA that cuts and splices RNA in eukaryotic cells
●Function as catalysts and are not used up in a chemical reaction
Generation of ATP
ATP is generated by the phosphorylation of ADP
Substrate-level phosphorylation
Substrate-level phosphorylation is the transfer of a high-energy PO4- to ADP.
Oxidation phosphorylation
Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain
Chemoautotroph
an organism that obtains energy by oxidizing inorganic chemicals, like sulfur or iron, and uses that energy to synthesize organic molecules from carbon dioxide, essentially “making its own food” using chemical energy instead of sunlight
Sulfur-oxidizing bacteria, nitrifying bacteria, iron-oxidizing bacteria
Chemoheterotrophs
an organism that gets its energy and carbon from organic sources. Chemoheterotrophs are unable to make their own organic compounds, so they must consume them from other organisms
Most animals, fungi, and many prokaryotes and protists are chemoheterotrophs
Photoautotroph
organism that uses light energy from the sun to produce organic molecules, essentially meaning it is an autotroph that generates its own food using photosynthesis; examples include most plants, algae, and some prokaryotes
Photoheterotroph
organism that uses light as its energy source but obtains carbon from organic compounds (like carbohydrates) in the environment, rather than from carbon dioxide like a photoautotroph; essentially, it harvests energy from sunlight but needs pre-existing organic matter for carbon building blocks
Photoautotroph vs. Photoheterotroph
photoautotroph is an organism that uses sunlight to generate its own food from inorganic carbon dioxide, while a photoheterotroph uses sunlight for energy but obtains carbon from pre-existing organic compounds found in the environment, meaning it cannot synthesize its own organic molecules from scratch like a photoautotroph can; essentially, a photoautotroph is a “producer” while a photoheterotroph is a “consumer” that uses light as its energy source.
Products of fermentation
-lactic acid
-ethanol
-CO2
-propionic acid
-acetic acid
-H2
-butyric acid
-Acetone
-isopropyl alcohol
-butanol
-succinic acid
-formic acid
-acetoin
-butanediol
Hydrolysis
Hydrolysis is a chemical reaction that breaks down large molecules into smaller ones by adding water.
Dehydration synthesis
dehydration reaction is a chemical process that removes water from a molecule or ion. It’s a type of condensation reaction, where two smaller molecules combine to form a larger one
What would be the likely outcome if you ⬆️[substrate] for an enzyme in the presence of a noncompetitve inhibitior?
No change
Bacteria and yeast are determined by…
Determining the action of their enzymes
Ex. Catalase produce by Staphylococcus
Glycolysis result
-e- carrier: produces 2NADH
-ATP yield: 2 (substrate -level phosphorylation)
Transition stage
-e- carrier: produces 2NADH
Krebs cycle
-e- carrier: 6 NADH and 2FADH2
-ATP yield 2 GTP
Aerobic respiration
-final hydrogen (e-) acceptor: O2
-type of phosphorylation used to generate ATP: substrate-level and oxidative
-ATP: 36 (e) and 38 (p)
Why do all enzymatic reactions need activation energy?
Energy is required to disrupt a substrate’s stable e- configuration
W/in the cytoplasm of bacterial cells are reserve deposits where certain nutrients accumulate. These are called _
Inclusions
Ex. Metachromitic granules, polysaccharid granules, lipid inclusions , sulfur granules, carboysomes, gas vacuoles
What molecule is broken down in cellular respiration, proving fuel for the cell?
Glucose
