Chapter 7 - The Cycles of a Cell Flashcards
What are autotrophs?
Converts radiant energy into chemical energy (self feeders)
What are heterotrophs?
Live on organic compounds that they consume (fed by others)
What is cellular respiration?
The central process in the energy metabolism which involves oxidation of organic compounds and using energy released to form ATP.
How is energy extracted from organic mixtures?
By rearranging CāH bonds via oxidation/reduction.
What is aerobic respiration?
When the electron acceptor is oxygen.
What is anaerobic respiration?
When the electron acceptor is an inorganic molecule other than oxygen.
What is fermentation?
When an organic molecule accepts electrons.
What is the chemical equation for burning carbohydrates?
C6H12O6 + 6 O2 ā> 6 CO2 + 6 H2O + energy (heat and ATP)
What makes up NAD+?
Two nucleotides which are nicotinamide monophosphate (NMP) and adenosine monophosphate (AMP) which are joined head-to-head by their phosphate groups.
How does NAD+ become NADH?
NAD+ acquires 2 electrons and a proton from the active site of an enzyme and is reduced to NADH.
What is substrate-level phosphorylation?
When ATP is formed by transferring a phosphate group directly to ADP from a phosphate-bearing intermediate or substrate.
What is oxidative phosphorylation?
When ATP is synthesized by the enzyme ATP synthase, using energy from a proton (H+) gradient.
How is the proton (H+) gradient formed?
High-energy electrons removed by oxidation of glucose passes down an electron transport chain.
What is the process of Glycolysis?
Converts glucose into 2 3-carbon molecules of pyruvate.
Where does glycolysis take place?
In the cytoplasm
How many net ATPs does glycolysis yield?
2 ATP
How many steps is the first half of glycolysis?
5 reactions
What happens in the first 3 steps of glycolysis?
It primes glucose by changing it into a compound that can be readily cleaved into 2 3-carbon phosphorylated molecules.
True of False: The first half of glycolysis needs 2 ATP in order to prime glucose.
True: Glycolysis begins by expending 2 ATP to transfer phosphate to each end of the glucose. This produces a 6-carbon molecule with two phosphates.
What is formed in the next 2 reactions of the first half of glycolysis?
2 3-carbon monophosphate sugars called glyceraldehyde-3-phosphate (G3P).
What is the 2nd to last step of glycolysis?
Each G3P is oxidized transferring 2 electrons and 1 proton to NAD+ forming NADH. A molecule of Pi is added to G3P to produce 1 3-biphosphatoglycerate (BPG).
What is the last step of glycolysis?
The phosphate incorporated is transferred to ADP by substrate-level phosphorylation in an exergonic reaction. 2 net ATP is formed
How much energy is produced with glycolysis?
14.6 kcal of energy per glucose
True or False: Cells contain a large amount of NAD+
False: a cell must oxidize NADH back to NAD+ in order for glycolysis to continue
What is the chemical equation for glycolysis?
glucose + 2 ADP + 2 Pi + 2 NAD+ ā> 2 pyruvates + 2 ATP + 2 NADH + 2 H+ + H2O
Where does the citric acid cycle take place?
In the mitochondria
How is pyruvate harvested?
Pyruvate is oxidized to produce a 2-carbon compound and CO2 with the electrons transferred to NAD+ to produce NADH.
The 2-carbon compound is oxidized to two molecules of CO2 by the reactions of the citric acid cycle.
What is the term of pyruvateās oxidation?
decarboxylation
How is acetyl-CoA formed?
By the decarboxylation of pyruvate from cleaving off one of pyruvateās three carbons. The remaining 2-carbon compound is acetyl-CoA.
What carbon group is fed into the citric acid cycle?
acetyl-CoA
What is acetyl added to?
The acetyl groups is added to 4-carbon acid oxaloacetate
What does acetyl turn into in the CAC?
It produces citrate
What happens to citrate in the CAC?
Citrate converts back to oxaloacetate, generating CO2 and transferring electrons and protons to the electron carriers NADH and FADH2.
How many ATP is generated by the oxidation of citrate?
1 ATP
True or False: The citric acid cycle produces a lot of ATP but does not produce a lot of NADH.
False: Very few ATP is generated but a large amount of NADH is generated for use in the electron transport chain.
How many reactions are in the citric acid cycle?
9 reactions
What is the first reaction of the CAC?
Condensation: Citrate is formed by joining acetyl-CoA to oxaloacetate.
What happens in reactions 2 and 3 of the CAC?
Isomerization: The hydroxyl (-OH) group of citrate must be repositioned. A water molecules is removed from one carbon and moved to another producing Isocitrate.
What is reaction 4 of the CAC?
The first oxidation: Isocitrate is oxidized in a decarboxylation reaction. Yields a par of electrons that reduce NAD+ to NADH. A central carboxyl group splits off to form CO2, produces A-ketoglutarate
What is reaction 5 of the CAC?
The second oxidation: A-ketoglutarate is decarboxylated by a multienzyme complex. CO2 is removed and joins to coenzyme A forming Succinyl-CoA. Two more electrons are extracted and reduce another NAD+ to NADH.
What is the 6th reaction of CAC?
Substrate-level phosphorylation: The bond of succinyl-CoA is cleaved and drives the phosphorylation of guanosine diphosphate (GDP) forming guanosine triphosphate (GTP). GTP can be converted into ATP. The molecule that remains is succinate.
What is the 7th reaction of the CAC?
The third oxidation: Succinate is oxidized to fumarate. FAD is the electron acceptor.
What are reactions 8 and 9 of the CAC?
Regeneration of oxaloacetate: a water molecule is added to fumarate to form malate. Malate is oxidized to oxaloacetate and two electrons reduce NAD+ to NADH.
How many NADH molecules are formed in the citric acid cycle?
10 molecules
How man FADH2 molecules are formed in the CAC?
2 molecules
How many net ATP molecules are formed in the CAC?
4 molecules.
What is the best method to understand the CAC?
Follow the electrons
Where does the electron transport chain take place?
In the inner mitochondrial membrane
What is the first to receive the electrons in the ETC?
NADH dehydrogenase
What is the carrier called that passes electrons to a protein called the bc1 complex?
Ubiquinone
What is the next carrier called that carried electrons to the cytochrome oxidase complex?
Cytochrome C
What does the cytochrome oxidase complex do?
It uses 4 electrons to reduce a molecule of oxygen. Each oxygen atom combines with two protons to form water.
How does the proton gradient form in the ETC?
The flow of highly energetic electrons induces a change in the shape of proton pump proteins which causes them to transport protons across the membrane.
What is chemiosmosis?
The chemical formation of ATP is driven by a diffusion force similar to osmosis
How does ATP synthases work?
Most of the protons that re-enter the matrix pass through ATP synthase which uses the energy of the gradient to catalyze the synthesis of ATP from ADP and Pi.
How many ATP is produced by NADH?
2.5 ATP
How many ATP is produced by FADH2?
1.5 ATP
How many ATP is yielded in aerobic respiration?
26-28 ATP
True or False: Bacteria have a higher ATP production.
True: Bacteria can produce up to 30-32 ATP.
What is produced in alcohol fermentation?
NAD+ and ethanol which is used to create wine.
What do muscle cells produce?
Converts pyruvate into lactic acid and regenerates NAD+.