chapter 25-cellular respiration Flashcards
cells need a quick and easy way to get energy for WHAT?
anabolism
ATP
-an unstable molecule, the bonds of which are easy to break making it a useful source of energy for cells
ADP -> ADP + P + free energy from food
food energy + ADP + P -> ATP
anabolic reaction
-driven by ATP
-replacement of cell parts (metabolic turnover), growth and cell division, and special functions (secretion, absorption, contraction, signaling)
what do catabolic reactions generate?
energy to make ATP
metabolism
the sum of all chemical reactions in the body; catabolism + anabolism
where do all energy productions begin?
the cytosol of the cell
what are protein molecules catabolized into that produce little energy?
amino acids
what are triglycerides catabolized into that produce little energy?
fatty acids & glycerol
what are carbohydrates catabolized into that produce little energy?
short carbon chains
40% of the food bond energy is used to generate ATP, and the other 60% becomes WHAT?
heat(used to maintain body temp.)
oxidation
the removal of electrons (or the addition of oxygen)
where do the smaller catabolized molecules arbored and processed in the reaction?
mitochondria
reduction
the addition of electrons
oxidation-reduction (redox reactions) reactions are always WHAT?
always coupled: one molecule must be oxidized while another is reduced
which happens when a molecule is reduced; it gains energy or it loses energy
gains energy
substrate level phosphorylation
when a high-energy phosphate is transferred directly from a substrate to ADP to form ATP
what happen when a molecule is oxidized?
loses energy
dehydrogenation reaction (more commonly performed by cells)
a hydrogen (1 proton + 1 electron) is exchanged instead of a free electron, but is still a redox reaction
reduces carrier compounds
catabolism of large molecules , which are then oxidized to generate ATP
during glycolysis, when the glucose is oxidized, what molecule gets reduced?
NAD+ (nicotinamide adenine dinucleotide) to become NADH
what three-carbon molecules are produced at the end of glycolysis?
pyruvic acid
acetyl
two-carbon molecule produced by decarboxylation
when citric acid is decarboxylated during the citric acid cycle, what molecule do the carbons become?
carbon dioxide (CO2)
glucose is C6 H 12 O 6, by the end of the citric acid cycle where have those 12 hydrogen atoms ended up?
on the carrier molecules NADH and FADH2
where specifically in a human cell is the electron transport chain?
on the cristae of the mitochondria
what is the final electron acceptor after the FMN, coenzyme Q and cytochromes have carried out a series of redox reactions?
oxygen
what is the enzyme that is necessary for oxidative phosphorylation at the end of the electron transport chain?
ATP synthase
of the 36 ATP that can be generated by aerobic respiration of glucose, how many were made by oxidative phosphorylation?
32
how much ATP (net gain) will be produced by the fermentation of glucose?
2
when triglycerides are used for ATP production, what is the glycerol converted into?
pyruvic acid
what is the process that converts fatty acids into two carbon fragments for use in the citric acid cycle?
beta oxidation
what vitamin does deamination require and produces ammonia?
B6
ammonia is diverted into what for excreation at the kidney?
urea
which two bases of RNA can be processed in the citric acid cycle for ATP production?
uracil (U) & cytosine (C)
which type of molecules generate the most energy for ATP production when processed under aerobic conditions: carbohydrates, lipids, proteins, or nucleic acids?
lipids
which type of molecules are the easiest for human cells to utilize for ATP production:
carbohydrates, lipids, proteins, or nucleic acids?
carbohydrates
what does the generation of ATP involve?
the addition of a phosphate to ADP and can be accomplished through substrate-level phosphorylation or oxidative phosphorylation
oxidative phosphorylation
-electrons are transferred from an organic compound to a cofactor carrier molecule
-the electron is passed through other carries(electron transport chain) to a final acceptor (oxygen)
-the passing of electrons releases energy that is harvested to add a phosphate to ADP
chemiosmosis
process of adding a phosphate to ADP from oxidative phosphorylation
what are the primary sources of cellular energy?
- carbohydrates (glucose)
- fatty acids(only when glucose in a short supply)
- amino acids
what are the two ways glucose can be catabolized for ATP production?
cellular respiration & fermentation
cellular respiration
-requires oxygen to serve as the final electron acceptor in a series of redox reactions that generate ATP by oxidative phosphorylation
-most efficient method of ATP production (1 glucose generates 32 ATP)
fermentation
-requires organic molecules to serve as the final electron acceptor & can be done without oxygen
-ATP is synthesized using substrate-level phosphorylation (1 glucose generates 2 ATP)
where are fermentation reaction carried out?
cytoplasm
where is cellular respiration reactions preformed?
mitochondria
what do fermentation reactions result in?
production of lactic acid
aerobic respiration of glucose
-oxygen involved
-C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O
-energy from 1 glucose -> 36 ATP
-three stages: glycolysis, citric acid cycle & electron transport chain
glycolysis
oxidation of glucose to pyruvic acid with some ATP & NADH(nicotinamide adenine dinucleotide + hydrogen) produced
citric acid cycle
oxidation & decarboxylation of acetyl to carbon dioxide with some ATP, NADH & FADH2 produced
electron transport chain
-NADH & FADH2 are oxidized providing an electron for a redox reaction that ultimately reduces oxygen to generate ATP
-the majority of ATP produced during this step
what are the coenzymes that function to transport electrons in the form of hydrogen?
NAD(nicotinamide adenine dinucleotide) & FAD(flavin adenine dinucleotide)
how many protons and electrons do NAD+ carry?
2 electrons but only 1 protons
how many complete hydrogen atoms does FAD carry?
2
where does glycolysis occur?
cytoplasm
what does glycolysis consist of?
-10-step metabolic pathway that catabolizes & oxidizes 1 glucose molecule into 2 pyretic acid molecules & generates 2 molecules of ATP by S.L.P
-many cells can only survive in glycolysis alone (fermentation) but it’s not efficient
what are two stages of glycolysis?
preparatory stage & energy conservation stage
preparatory stage of glycolysis
two ATP molecules are used to phosphorylate one 6-carbon glucose and catabolize it into two 3-carbon molecules
energy conservation stage
-the two 3-carbon molecules are oxidized to generate two 3-carbon pyruvic acid molecules
-at the same time 2 NAD+ molecules are reduced to two NADH molecules & 4 ATP molecules are produced by S.L.P
decarboxylation (preparation for the citric acid cycle)
-the first step in the aerobic processes of glucose metabolism
-only occurs when oxygen is available & takes place in the matrix of mitochondria
-the 3-carbon pyruvic acid is decarboxylated into carbon dioxide & 2-carbon acetyl
-acetyl is oxidized and attached to coenzyme A (carrier) as one NAD+ is reduced to NADH
-only happens twice
what does the citric acid cycle (Krebs cycle or tricarboxylic acid cycle)
-involves 8 enzymatic reactions occurring in the mitochondrial matrix that function to reduce NAD+ & FAD
-the 2-carbon acetyl is attached to a 4-carbon oxaloacetic acid creating a 6-carbon citric acid
-oxidation & decarboxylation reactions occur which catabolize the 6-carbon citric acid back into a 4-carbon oxaloacetic acid & two carbon dioxide molecules
-at the same time 3 NAD+ & 1 FAD are reduced into three NADH & 1 FADH2, and 1 ATP is produced by S.L.P
-only runs two times
where does electron transport chain take place and what does it do?
-oxidative phosphorylation occurs on a membrane, mitochondrial cristae, to generate most of the ATP produced by glucose
-coenzymes from the previous reactions pass electrons to a series of electron carrier molecules, which carry out redox reactions resulting in the chemiosmotic generation of ATP
what are the three classes of carrier molecules in the cristae membrane
- FMN
- coenzyme Q
- cytochromes
what is an FMN carrier molecule?
flavin mononucleotide (protein + flavin coenzyme)
what is coenzyme Q carrier molecule?
a nonprotein
what are cytochromes carrier molecules?
-protein + an iron group
-most common
what are the first two events of the electron transport chain
- NAD+ & FAD collected energy in form of hydrogen atoms from organic molecules during glycolysis, decarboxylation & citric acid cycle becoming reduced forms NADH & FADH2
- NADH & FADH 2 are oxidized & pass hydrogen atoms to the electron transport chain, as electrons are passed along the chain protons are pushed out through cristae membrane into the space under outer mitochondrial membrane that sets up a concentration gradient with protons (+ charge) on outside and electrons (- charge) on outside of matrix
what are the third and fourth events of the electron transport chain?
- at the end of the chain, electrons are accepted by oxygen creating an anion (O-) inside which has a strong affinity for the cations (H+) outside
- chemiosmosis generates ATP: H+ from the outside moves toward O- on the inside through special membrane channels that are coupled to ATP synthase and the high-energy diffusion of H+ drives the reaction, the energy from 1 NADH from glycolysis can generate 2 ATP the energy from 1 NADH from decarboxylation & citric acid cycle can generate 3 ATP that form FADH2 can generate 2 ATP for a total of 32 ATP
what is the last event of the electron transport chain?
H+ combines with O- inside the mitochondria creating water (H2O)
how many electrons do glycolysis, citric acid cycle & decarboxylation?
glycolysis: 2
citric acid cycle: 2
electron transport chain: 32
lipolysis (lipid catabolism)
-hydrolyzes triglycerides into glycerol and three fatty acids
-glycerol is converted into pyruvic acid in the cytoplasm and catabolized through the citric acid cycle in the mitochondria
-fatty acids are catabolized by beta-oxidation in the mitochondria to be entered into the C.A.C as two-carbon fragments
-can generate 17 molecules of ATP
-always requires oxygen & is slow
protein & amino acid catabolism
-not a very good source of energy
-burns more energy than produced
nucleic acid catabolism
-DNA is never catabolized for energy
-RNA can be broken down into simple sugar & nitrogenous bases
-sugars are metabolized by glycolysis but only uracil & cytosine and are proceesed through the C.A.C