METABOLISM, ANABOLISM AND CATABOLISM
metabolism
metabolism is the total sum of chemical reactions within the body of an organism (anabolic + catabolic reactions)
METABOLIC PATHWAYS are essential for producing things that are essential for cells to function
plants : production of glucose, chlorophyll
animals: production of vitamins, haemoglobin
enzymes often play an important role in metabolic pathways
all metabolic pathways together form a network for maintaining life
TYPES OF METABOLIC PATHWAYS
catabolic pathway
anabolic pathway
pathway that releases energy during break down of bonds (from large molecules to smaller molecules)
pathway that requires energy during formation of bonds (from smaller molecules to larger molecules)
exergonic reaction
endergonic reaction
eg: PHOTOSYNTHESIS
CELLULAR RESPIRATION/DIGESTION
CATABOLISM
chemical reaction in which complex substances are broken down into simpler substances
AB = A + B
releases energy
exergonic reaction
food digestion : starch (polysaccharides) --> simple sugars (monosaccharides)
glucose is broken down into carbon dioxide and water during tissue respiration
proteins and amino acid are deaminated in the liver to form urea
ANABOLISM
reaction in which simple substances are built up into more complex substances
A + B = AB
requires energy
important for growth and repair of damaged or worn out tissues
conversion of glucose to glycogen in the liver and muscles
process of photosynthesis in green plants
formation of new proteins from amino acids
example of metabolism
catabolism
the potato gets digested by the animal to make glucose
potato = starch = polysaccharides
glucose are oxidised to make ATP (energy) for the body
starch > glucose [polysaccharides > monosaccharides]
anabolism
excess glucose are made into glycogen or fat for long term storage in the body
glucose > glycogen [monosaccharides > polysaccharides]
complex > more complex
complex > less complex
METABOLISM AND ENERGY FLOW
anabolism + catabolism = metabolism
chemical reaction converts one set of chemical substances, the reactants, into another set, the products
all chemical reactions either release energy (exergonic) or require input of energy (endergonic)
breaking or forming of bonds require energy
in living organisms, potential energy ('stored energy') will often be transformed into kinetic energy ('energy of motion')
energy is defined as the capacity to do work
metabolic pathways and energy flow
exergonic reaction releases energy
the reactants have more energy than the end products
gives off some energy such as heat, light and ATP
occurs during catabolism
example: cellular respiration
glucose + oxygen (reactants) = energy released (ATP) + carbon dioxide + water (products)
glucose is broken down in to carbon dioxide and water
cellular respiration is an important exergonic reaction in humans - provides energy for life
glucose
major breakdown product of carbohydrate digestion
major fuel used for making ATP
oxidised during respiration to release energy for vital activities of the cells
metabolic pathways and energy flow
endergonic reaction requires energy
requires an influx of energy from an outside source
products contain more energy than the reactants
occurs during anabolism
example : photosynthesis
carbon dioxide + water (reactants) + energy (from sunlight) = oxygen + glucose (products)
green plants uses solar energy for sugar (glucose) and oxygen from carbon dioxide and water
most of the biological reactions in an organism are endergonic reactions. they require energy to drive reactions for making molecules and doing work in the cell
energy created by exergonic reactions are used by cells for energy required in endergonic reactions
ENERGY COUPLING
the use of energy released from exergonic reactions (usually in the form of ATP) to drive essential endergonic reactions
in the form of ATP because energy has to be quickly stored somewhere or else it will heat up the cell and you will die
ATP molecules are the key to energy coupling
METABOLIC PATHWAYS OF CARBOHYDRATES : CELLULAR RESPIRATION
in cellular respiration, food molecules are broken down and their energy are captured in ATP molecules
FOUR main carbohydrate metabolic pathways that are involved with cellular respiration
- Glycolysis
- Acetyl-CoA formation
- Krebs Cycle
- Electron Transport Chain
occurs in the cytoplasm
occurs in the mitochondria
occurs in the mitochondrial matrix
occurs in the inner membrane of mitochondria