Plant and Animal Tissue Culture
What the domain covers
Plant and animal tissue culture tests the principles of growing cells outside the organism: totipotency, explant selection, callus, micropropagation, somatic embryogenesis, anther culture, protoplast culture, and animal cell culture systems. Expect questions on media, hormones, aseptic technique, and sources of variation.
Core rules and concepts
- Plant tissue culture relies on totipotency-the ability of a plant cell to regenerate a whole plant under suitable conditions.
- A typical micropropagation sequence is explant → surface sterilisation → callus or direct shoot induction → rooting → hardening → field transfer.
- Auxin and cytokinin ratios steer development: higher cytokinin favours shoot formation; higher auxin favours root formation; intermediate ratios favour callus.
- Animal cells require complex media, often with serum, and strict aseptic conditions. Primary cultures have limited lifespan; continuous cell lines can be subcultured indefinitely.
- Somaclonal variation arises during culture and can be useful or harmful; protoplast fusion can combine genomes from different species.
Worked example
A leaf explant is placed on medium with high cytokinin and low auxin. After weeks, multiple shoots form. Reasoning: cytokinin promotes shoot initiation, while low auxin permits shoot development rather than callus or root dominance. The shoots are then transferred to rooting medium with higher auxin before hardening.
Traps
Do not say callus is always required; some systems use direct organogenesis. Do not treat plant and animal media as interchangeable. Do not ignore aseptic technique-contamination can outgrow slow cultures. Do not assume all regenerated plants are genetically identical.