Chapter 3: Section E: Metabolic Pathways AKA DEATH Flashcards
1
Q
Cellular respiration
A
- process by which a series of metabolic reactions uses the energy in food to produce ATP
- 3 main processes: 1) glycolysis 2) Krebs cycle 3) oxidative phosphorylation
2
Q
Aerobic respiration
A
- requires O2
- in mitochondria
- glucose is completely broken down
- generates 36 ATP
3
Q
Anaerobic respiration
A
- doesn’t require O2
- in cytosol
- glucose is incompletely broken down generating only 2 ATP
4
Q
Glycolysis
A
- takes place in cytosol
- generates 2 ATP molecules via substrate-level phosphorylation, 2 NADH molecules, and 2 pyruvic acid (pyruvates)
- in absence of O2, pyruvate undergoes fermentation
- if O2 present, pyruvate enters mitochondrion and aerobic respiration proceeds
- under anaerobic conditions of high demand, lactate is created when muscles working hard
5
Q
Transitional step
A
- under aerobic conditions in mitochondrial matrix
- pyruvic acid is converted to acetyl-CoA
- 2 pyruvate + 2 Coenzyme A = 2 acetyl-CoA + 2CO2 + NADH
- acetyl-CoA enters Krebs cycle
6
Q
Krebs Cycle (citric acid cycle)
A
- occurs in mitochondrial matrix
- generates: 2 ATP, 6 NADH, 2 FADH2 (34 CO2 waste product)
- turns twice per molecule of glucose (2 acetly coa)
7
Q
Oxidative phosphorylation/Electron transport chain
A
- located on cisternae (folds of inner mitochondrial membrane)
- made of series of integral membrane proteins (cytochromes) that act as electron carriers
- NADH and FADH2 donate e- to ETC
- electrons are passed from one cytochrome to next, it drives the pumping of H+ ions from inner compartment of the mitochondrion to the outer compartment
- O2 is the final electron acceptor! Is reduced and combines with H+ to form H2O without O2 the chain stops!!!
8
Q
Chemiosmotic hypothesis
A
- ATP synthases (enzyme complexes associated with the inner mitochondrial membrane) and they catalyze the production of ATP
- ADP+Pi –> ATP
- ATP synthase activity is driven by H+ moving through it. H+ move from increase to decrease concentration
- for every NADH that reaches ETC, 3 ATP made
- for every FADH2, 2 ATP made
9
Q
Carbohydrate Metabolism
A
- glucose catabolism results in ATP synthesis via a combination of substrate-level and oxidative phosphorylation
- glycogen storage and breakdown
- enzymes located in cytosol
- excess of glucose in liver or muscle cells –> glycogenesis
- deficiency of glucose –> glycogenolysis activated
- glycogen –> glucose - 6- phosphate
- G-6-P undergoes glycolysis in most cells
- G-6-P can be converted to free glucose in liver and kidney cells and enters blood
10
Q
Glycogenesis
A
synthesis of glucose from non-carbo sources in liver and kidney cells
- enzymes located in cytosol for process
- controlled by hormones released in response to changes in blood sugar levels
11
Q
Fat metabolism
A
- 78% body = triglycerides
- fatty acid catabolism occurs in mitochondria
- one gram of fat generates about 2.5 times as much ATP as 1 gram of carbo
- process initiated by linking a coenzyme A molecule to the carboxyl end of fatty acid
- fatty acid derivative then undergoes beta oxidation
- splits off an acetyl CoA molecule from the fatty acid which removes 2 carbons
- another CoA is added and cycle repeats until all C atoms have been transferred
- acetyl coA enters the krebs
- transfers a pair of H atoms to FAD and NAD+ (oxidative phosphorylation)
- fatty acid synthesis involves same enzymes and reactions as catabolism but in reverse
- enzymes located in cytosol
- 2 carbons at a time are added to growing fatty acid via acetyl coa
- fatty acids are joined to glycerol via enzymes associated with sER –> triglyceride
- glucose can be readily converted into fat, but the fatty acid portion of fat cant be converted into glucose
12
Q
catabolism
A
- proteases: splits off one amino acid at a time OR breaks peptide bonds between specific amino acids, forming peptides
- amino acids can be catabolized to produce ATP, reused in protein synthesis, or to provide intermediates for the synthesis of molecules other than proteins
13
Q
Steps of catabolism
A
1) amino group must be removed from the amino acid through oxidative deamination or transmination
2) remainder of the amino acid can be metabolized to intermediates that enter the krebs cycle or glycolytic pathway, undergo glyconeogenesis, etc
14
Q
oxidative deamination
A
- amino group removed from amino acid and converted to ammonia and then an O2 atom replaces amino group forming keto acid
15
Q
transamination
A
- amino group is transferred from amino acid to keto acid
- the amino acid from which the amino group has been removed has an oxygen added forming keto acid
- keto acid picks up amino acid
- responsible for converting one amino acid to another
