SCI1186 Lecture Notes - Lecture 9: Middle Lamella, Plasmodesma, Vacuole
16 Jun 2018
School
Department
Course
Professor
Week 8 & 9 - Plant Cells, Tissues, Stems and Roots
PLANT CELL
Cell: individual building blocks of organisms. The simplest collection of matter that can be alive
Structure: the form of the organism. How it is made
Components: the function of the organisms
Plant and animal cells have many organelles in common:
• Nucleus
• Mitochondria
• Cell membrane
• Golgi body
Animal cells don’t have:
• Chloroplasts
• Central vacuole
• Tonoplast
• Cell wall
• Plasmodesmata
Cell wall:
• Only found in plant cells
• Allows the cell to grow as the wall has a rigid structure
• All have primary wall, only some have a secondary wall which is separated by a middle lamella
• Nutrients are transported in and out of the cell through small ‘windows’ in the cell wall (plasmodesmata)
Primary wall:
• Found in the innermost part of the cell wall
• Found in plant cells
• Made of thin strands of cellulose in order to allow cell growth
• Cell grows by breaking down the wall, stretching and then adding more fibres
Secondary wall:
• Outermost part of the cell wall
• Found in the bark and wood of plants
• Not all plants have a secondary wall
• Made of lignin to enable rigidity
• When the secondary wall matures, the middle part of the cell dies
Plasmodesmata:
• Communication between cells and transport of nutrients
• Done through plasma membrane and gaps in the fine cell wall
• Allows plants to respond to the changing environment as diffusion is too slow
Chloroplast:
• Type of plastid organelle
• Has a double membrane
• Acts as the site of photosynthesis (energy being harvested from sunlight)
o Fuels plant
Vacuole:
• Membrane bound organelles
• Store metabolites and pigments
• Storage area for water which contains solutes to maintain the water balance of the cell
• When the water evaporates, the plant wilts
• As it matures, it fuses with other vacuoles to form a central vacuole
Document Summary
Week 8 & 9 - plant cells, tissues, stems and roots. The simplest collection of matter that can be alive. Plant and animal cells have many organelles in common: nucleus, mitochondria, cell membrane, golgi body. Animal cells don"t have: chloroplasts, central vacuole, tonoplast, cell wall, plasmodesmata. Plasmodesmata: communication between cells and transport of nutrients, done through plasma membrane and gaps in the fine cell wall, allows plants to respond to the changing environment as diffusion is too slow. Chloroplast: type of plastid organelle, has a double membrane, acts as the site of photosynthesis (energy being harvested from sunlight, fuels plant. Tissue: a group of similar cells organised into a structural and functional unit. Simple tissue: a collection of the same cell types in one tissue. Complex tissue: multiple cell types found in the same tissue. Primary tissue: tissue that develops in the early stages of the plant (leaves) Secondary tissue: tissue that develops when a plant matures (flowers, fruit)
