Metabolism, Cellular Respiration, etc. Flashcards
includes basic definitions, glycolysis, kreb cycle, pyruvate oxidation, electron transport chain, etc.
what is metabolism
the sum of the biochemical reactions in a living system
what is catabolism
the process of breaking down compounds into smaller molecules to release energy
eg. breakdown of glucose to make ATP
what is anabolism
the process of using energy to build large molecules
eg. making proteins
what are metabolic pathways
step-by-step sequences where one or more substrates form a product that becomes the substrate for the next step; each reaction is catalyzed by an enzyme
What is ATP
adenosine triphosphate
~ the energy that drives and links certain reactions
What is substrate level phosphorylation?
phosphate group is transferred from one molecule to another
ex. when a phosphate group is transferred from a substrate to ADP to form ATP
what are redox rxns
- the transfer of electrons between two species or compounds
LEO lion says GER
~ Loss of Electrons is Oxidation
~ Gain of Electrons is Reduction
What are the “Substrates”/molecules involved in the Kreb cycle
1 molecule of glucose → 2 pyruvate → 2 acetyl coA
CIKSSFMO
Acetyl CoA → citrate → isocitrate → alpha ketoglutarate → succinyl CoA → succinate → fumarate → malate → oxaloacetate
What are the enzymes that catalyze the molecules/substrates of the Kreb Cycle?
(1) Citrate → citrate synthetase
(2 & 3) Citrate to isocitrate → aconitase
(4) Isocitrate to alpha ketoglutarate → isocitrate dehydrogenase
* FIRST REDOX RXN
* PRODUCES CO2
* REDUCES NAD+ INTO NADH + H+
(5) Alpha ketoglutarate to succinyl CoA → dehydrogenase
* 2ND REDOX RXN
* NAD+ IS REDUCED TO NADH + H+
* PRODUCES CO2
(6) Succinyl CoA to succinate → succinyl CoA synthetase
* ONLY ENZYME THAT PRODUCES ATP THROUGH SUBSTRATE LVL PHOSPHORYLATION
* PHOSPHATE GROUP REPLACES THE COA WHICH IS THEN ADDED TO A MOLECULE OF GTP WHICH TRANSFERS IT OFF TO ADP TO PRODUCE ATP
(7) Succinate to fumarate → succinate dehydrogenase
* REDOX RXN #3
* REDUCTION OF FAD TO FORM FADH2
(8) Fumarate to malate → fumarase
(9) Malate to oxaloacetate → malate dehydrogenase
* REDOX RXN #4
* REDUCES NAD+ INTO NADH + H+
THE CYCLE REPEATS!
How many carbons are present in each part of the kreb cycle
glycolysis → 6C
pyruvate → 3C
acetyl CoA → 2C
citrate → 6C
isocitrate → 6C
alpha ketoglutarate → 5C
succinyl CoA → 4C
succinate → 4C
fumarate → 4C
malate → 4C
oxaloacetate → 4C
What are the products of the kreb cycle
FOR EACH PYRUVATE:
1 ATP
3 NADH
1 FADH2
2 CO2
FOR EACH GLUCOSE:
2 ATP
6 NADH
2 FADH2
4 CO2
Where does the krebs cycle occur?
occurs in the mitochondrial matrix when oxygen is present
in terms of pyruvate oxidation under aerobic conditions, what does 1 GLUCOSE yield
2 Acetyl CoA molecules
2 NADH
2 CO2
how to calculate ATP yield for carbohydrates
Depends on the cell type:
~ PROKARYOTIC (no membrane) = 38 ATP/glucose
~ EUKARYOTIC (membrane) = 36 ATP/glucose
~ *** heart liver and kidney = 38 ATP/glucose
1) first determine how many glucose are produced (both fructose and galactose yield the same # of ATP as glucose)
2) multiply by the number of ATP depending on the description (ex. prokaryotic, eukaryotic, in the heart, liver or kidney)
What is glycolysis? where does it occur?
glycolysis is the conversion of glucose (6C) into pyruvate (3C); occurs in the cytoplasm and no oxygen is required
What is a dehydrogenase enzyme
A dehydrogenase enzyme oxidizes the substrate by removing hydrogens and associated electrons and transferring them to an electron acceptor (ex. NAD+ to NADH + H+).
What are kinases
enzymes that chemically add a phosphate group to a substrate molecule
(eg. ADP → ATP; phosphorylation)
What are isomerases
enzymes that catalyze a structural rearrangement of a molecule
eg. (DHAP → G3P; ketone to aldehyde)
For every glucose that goes through glycolysis, how much ATP is made
2 molecules of ATP
What are electron carriers? specify examples
electron carriers are compounds that pick up electrons and donate them to low-energy compounds
eg. NAD+ to NADH
eg. FAD+ to FADH2
What are the 10 steps of glycolysis? include the names of the substrate, enzyme, and where ATP is used.
- Glucose → Glucose-6-Phosphate: Hexokinase
~ ATP TURNS TO ADP - Glucose-6-Phosphate → Fructose-6-Phosphate: Isomerase
~ aldehyde to ketone - Fructose-6-Phosphate → Fructose 1,6 Bisphosphate: Kinase
~ ATP TURNS TO ADP - Fructose 1,6 Bisphosphate → Dihydroxyacetone phosphate (DHAP): Aldolase
~ where 6C chain breaks to 3C - Dihydroxyacetone phosphate (DHAP) → Glyceraldehyde-3-Phosphate (G3P): Isomerase
~ also a 3C
~ can go to DHAP to G3P or the other way around - Glyceraldehyde-3-phosphate to 1,3 Bis Phosphoglycerate (1,3 BPG) → G3P dehydrogenase
~ THIS STEP HAPPENS TWICE
~ NAD+ BECOMES NADH (REDOX RXN) - 1,3 Bis Phosphoglycerate (1,3 BPG) → 3-Phosphoglycerate: Kinase
~ ADP TURNS TO ATP - 3-Phosphoglycerate → 2-Phosphoglycerate: Mutase
~ Phosphate goes from C3 to C2 - 2-Phosphoglycerate → Phosphoenol Pyruvate: Enolase
- Phosphoenol pyruvate → pyruvate: Kinase
~ ADP TURNS TO ATP
~ 3C
~ TWO PYRUVATES ARE FORMED
what is oxidative phosphorylation
oxygen is the final electron acceptor
Where does pyruvate oxidation occur
the mitochondrial matrix
What are the steps of pyruvate oxidation? Whats the enzyme that catalyzes this reaction
- pyruvate is broken down to acetate
- CO2 is produced
- Remainder binds to coenzyme A to produce acetyl-CoA
- NAD+ is reduced to form NADH
the enzyme that catalyzes this rxn is pyruvate dehydrogenase complex (3 enzymes)
In terms of the Electron transport chain, how many ATP does each NADH and FADH2 make?
each NADH makes 3 ATP
each FADH2 makes 2 ATP
Where does the electron transport chain (aka oxidative phosphorylation) occur?
in the mitochondria; series of protein complexes are located in the inner mitochondrial membrane (cristae)
What is the risk of having a lot of heat released from an exothermic biochemical reaction?
the increase in temperature will denature proteins in the cell
What are the names of the 3 proteins involved in the mitochondrial electron transport chain
I (1) - NADH dehydrogenase
III (3) - bc1 complex
IV (5) - Cytochrome c oxidase
what does the ATP synthase protein complex allow?
complete diffusion of H+ ions down their gradient back into the matrix
Every 2 H+ ions that diffuse back through, one ADP is phosphorylated to ATP
describe the idea of reaction coupling
- our bodies have both exothermic and endothermic reactions happening
- if an endothermic rxn is happening nearby and at the same time, then the heat from one reaction can be used to drive the reaction that requires heat
- for example, in cells, energy from catabolic rxns is used to power anabolic rxns
What is the equation for cellular respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water)
What are the key steps of the electron transport chain
- NADH/FADH2 donate electrons to protein complexes in the cristae. This reforms NAD/FAD
- NADH electrons pass through all 3 complexes & FADH2 electrons only pass through 2
- H+ ions remind behind in the matrix solution. The protein complexes actively pump H+ ions out of the matrix against the gradient
- H+ ion gradient builds up in the intermembrane space
- 2 electrons are finally donated to an oxygen atom and combined with 2H+ ions to form water
In terms of fates of pyruvate; under anaerobic conditions, what is OXYGEN DEBT?
the amount of oxygen required to eliminate/remove the lactate
Fates of pyruvate; under anaerobic conditions:
What are 2 other organic compounds that can be produced besides lactate and ethanol?
butanol and acetone
what are the final electron acceptors for aerobic respiration, anaerobic respiration, and fermentation?
aerobic - oxygen
anaerobic - inorganic molecule
fermentation - organic molecule
What is lactate fermentation?
- in the absence of oxygen, pyruvate gets reduced to LACTATE (organic molecule)
- occurs in some bacteria & eukaryotic cells
- electrons are transferred from NADH to pyruvate to produce lactic acid
What is alcohol fermentation?
- OCCURS IN UNICELLULAR ORGANISMS LIKE YEAST
- in the absence of oxygen, pyruvate gets reduced to ethanol and carbon dioxide
- NADH is oxidized into NAD+
- an intermediate, 2-acetaldehyde is produced which accepts electrons from NADH to form ethanol
What are some applications/uses of ethanol fermentation in society?
- used to manufacture baking goods and alcoholic beverages (ex. yeast)
- used during the war to make weapons and gun powder
- used as lamp fuel, in engines, and other machinery
