Cell Metabolism
Mitochondria
Organelles that facilitate the process of aerobic respiration in eukaryotic cells
Has two membranes and the inner mitochondrial membrane contains enzymes that facilitates the final stage of aerobic respiration including ATP synthesis.
Outer membrane- lipid bilayer membrane containing carrier and channel proteins as well as embedded enzymes that catalyse chemical reactions in the cytoplasm.
Cristae: These extensions of the inner mitochondrial membrane increase SA/V of the inner mitochondrial membrane and hence the rate of ATP synthesis.
Matrix: The space enclosed by the inner mitochondrial membrane. The matrix contains mitochondrial DNA, ribosome and enzymes that carry out important biochemical reaction
Intermembrane spaces: The space between the outer and inner membrane receives protons and other substances during the process of ATP synthesis to produce concentration gradients that then provide energy for ATP synthesis
Chloroplasts
organelles that facilitate the process of photosynthesis
A chloroplast has membrane- bound compartments called thylakoids that are arranged into stacks called grana (singular granum). The grana greatly increase the surface area to volume ratio for the attachment of pigments and enzymes that facilitates photosynthesis
Inner and outer membrane: regulate the transport of materials between the stroma and the cytoplasm of a plant cell. The inner membrane contains enzymes that carry out the synthesis of some pigments and lipids.
Thylakoids: Membrane bound sacs containing light-absorbing pigments and enzymes that are involved in photosynthesis
Granum: stack of thylakoids. increase SA/V of light absorbing pigments which increase the rate of photosynthese
Stroma: A gel-like fluid that contains enzymes that carry out chemical reactions in the photosynthesis
Stromal lamellae: Extensions of the thylakoids membrane that increase the SA/V of light absorbing pigments which increase the rate of photosynthesis
Metabolic pathway
a series of enzyme- catalysed reactions that occur in a cell
Each step is catalysed by a specific enzyme that lowers the activation energy for a particular reaction
Enzymes increase the rate of metabolic reactions by reducing the activation energy of each step
Different enzymes allow reactions to occur at variable rates dependent on concentrations of substrate, product and enzyme and presence of inhibitors
Metabolic pathway require many small regulated steps to ensure that the amount of heat released at each step is small, hence will not reduce the activity of enzymes in a cell. In addition, some steps in a metabolic pathway produced intermediate compounds that serve an essential function in the cell. In some cases, the intermediate compounds act as activators or inhibitor of other enzymes in a metabolic pathway.
Environmental factors and effect on metabolism
Temp: increase the rate of enzyme-catalysed reactions until the optimum temp is reached. The reaction rate decreases at higher temp as the enzyme becomes denatured
Light intensity- The rate of the light- dependent reaction in photosynthesis is affected by the intensity and wavelength of light absorbed
pH- alters the 3D shape of an enzyme which decreases the rate of reaction
Availability of water: Enzyme-catalysed reactions occur in the aqueous solution inside a cell
Availability of substrate and enzyme: the reaction is dependent on these. Metabolic reactions occur more rapidly when there is a high concentration of enzyme and substrate in the cell