They say how an enzyme perfectly fits into its substrate is alike a "lock and key".
Only one specific enzyme can fit a specific substrate.
In unicellular organisms such as bacteria, mitosis helps in asexual reproduction as it produces an identical copy of the parent cell. ... In the case of multicellular organisms, mitosis helps in growth and repair by producing more number of identical cells.
Nuclear envelope.
Endoplasmic reticulum.
Golgi apparatus.
Vacuoles.
Vesicles.
Lysosomes.
Spitzenkörper.
Plasma membrane.