metabolic pathways
DESCRIPTION
Metabolic Pathways. Metabolism and Cell Structure ATP and Energy Important Coenzymes in Metabolic Pathways Coenzyme NAD + Coenzyme FAD Coenzyme A. Metabolic Pathways. Metabolism. Metabolism involves: - PowerPoint PPT PresentationTRANSCRIPT
Metabolism and Cell Structure ATP and Energy Important Coenzymes in Metabolic
Pathways Coenzyme NAD+
Coenzyme FAD Coenzyme A
Metabolic Pathways
Metabolic Pathways
Metabolism involves: Catabolic reactions that break down large,
complex molecules to provide energy and smaller molecules.
Metabolism
Anabolic reactions that use ATP energy to build larger molecules.
Stages of Metabolism
Catabolic reactions are organized as stages: In Stage 1, digestion breaks down large molecules
into smaller ones that enter the bloodstream. In Stage 2, molecules in the cells are broken down
to two- and three-carbon compounds. In Stage 3, compounds are oxidized in the citric
acid cycle to provide energy.
Stag
es o
f Met
abol
ism
Cell StructureMetabolic reaction occur in specific sites within cells.
Cell Components and Function
ATP and Energy In cells, energy is stored in adenosine triphosphate
(ATP).
Hydrolysis of ATP
The hydrolysis of ATP to ADP releases 7.3 kcal (31 kJ/mole). ATP ADP + Pi + 7.3 kcal (31 kJ/mole)
The hydrolysis of ADP to AMP releases 7.3 kcal (31 kJ/mole). ADP AMP + Pi + 7.3 kcal (31 kJ/mole)
Hydrolysis of ATP to ADP and ADP to AMP
ATP and Muscle Contraction
Muscle fibers contains filaments of actin and myosin.
When a nerve impulse increases Ca+2, the filaments slide closer together to contract muscle.
The hydrolysis of ATP in muscle provides the energy for contraction.
As Ca+2 and ATP decrease, the filaments return to the relaxed position.
ATP
and
Mus
cle C
ontra
ctio
n
Coenzyme NAD+
In cells, the oxidation of compounds provides 2H as 2H+ and 2e- that reduce coenzymes.
NAD+ (Nicotinamide Adenine Dinucleotide) participates in reactions that produce a carbon-oxygen double bond (C=O).Oxidation O
||CH3—CH2—OH CH3—C—H + 2H+ + 2e-
ReductionNAD+ + 2H+ + 2e- NADH + H+
Structure of Coenzyme NAD+
NAD+ (nicotinamide adenine dinucleotide) contains ADP, ribose, and nicotinamide.
NAD+ reduces to NADH when the nicotinamide group accepts H+ and 2e-
Coenzyme FAD FAD participates in reactions that produce a
carbon-carbon double bond (C=C).
Oxidation —CH2—CH2— —CH=CH— + 2H+ + 2e-
ReductionFAD + 2H+ + 2e- FADH2
Structure of Coenzyme FAD
FAD (flavin adenine dinucleotide) contains ADP and riboflavin (vitamin B2)
FAD reduces to FADH2 when flavin accepts 2H+ and 2e-
Coenzyme A CoA activates acyl groups such as the two-carbon
acetyl group for transfer. O O || ||
CH3—C— + HS—CoA CH3—C—S—CoA