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