Plant Cell Structure and Function

Plant Cell Structure and Function

• Plant cells are the basic building blocks of plant structure, playing critical roles in processes like gas exchange, water transport, photosynthesis, and ion transport.

• Plant structure and function are interconnected, with structure enabling function.

Plant Body Plan

• Seed plants have a consistent body plan with three primary organs: leaves (photosynthesis), stems (support), and roots (anchorage, water/mineral uptake).

• Leaf attachment occurs at nodes, with internodes being the stem sections between successive nodes. The shoot is the stem combined with its leaves.

• Two main seed plant categories are gymnosperms (naked seeds), exemplified by conifers (pine, fir, etc) and angiosperms (enclosed seeds) which are the dominant flowering plants.

• Plant growth occurs in specialized cell division zones called meristems, particularly apical meristems at shoot and root tips, and axillary buds.

Plant Cell Walls

• Plant cells differ from animals in being surrounded by rigid cell walls that facilitate vertical plant growth and support.

• Cell growth is restricted by adjacent cells interconnected via the middle lamella.

• There are two types of cell walls: primary (thinner, young growing cells) and secondary (thicker, stronger, and often lignified, for support).

Biological Membranes

• Plant membranes are phospholipid bilayers containing proteins.

• Phospholipids are amphipathic, meaning they have both hydrophilic (polar) and hydrophobic (nonpolar) regions. Plant membranes use unsaturated fatty acids to maintain fluidity under variable temperatures.

• Membrane proteins (integral, peripheral, and anchored) are responsible for selective traffic across the membrane and performing other vital cell processes.

The Nucleus

• The plant nucleus is the primary site for genetic material storage and regulation.

• Plant genomes vary significantly in size, with some being larger than others.

• DNA is organized into chromatin, a complex with proteins.

• Nucleosomes are fundamental packaging units in which DNA is coiled around histone proteins.

• The nucleus contains the nucleolus, a site for ribosome synthesis containing rRNA genes.

The Cytoplasm

• The endoplasmic reticulum (ER) is an extensive internal membrane network consisting of smooth and rough forms.

• Smooth ER is involved in lipid synthesis and membrane assembly.

• Rough ER plays a crucial role in protein synthesis and secretion for extracellular use and vacuoles.

Golgi Apparatus

• The Golgi apparatus, or Golgi body, is a stack of cisternae (flattened membrane sacs) involved in post-translational processing of proteins and the synthesis of polysaccharides.

• Plants may have hundreds of Golgi bodies distributed throughout the cytoplasm.

• Glycoproteins experience further modifications to get targeted to their correct location.

Central Vacuole

• The central vacuole is a large, water-filled compartment in mature plant cells, contributing substantially to cell volume.

• The vacuole is enclosed by the tonoplast, managing the contents within the vacuole.

• Both water and solutes are present in the vacuole.

Other Structures

• Protein bodies store proteins.

• Lytic vacuoles have enzymes for hydrolysis of macromolecules.

Explore the essential roles of plant cells in vital processes such as gas exchange, photosynthesis, and nutrient transport. Understand the interconnectedness of plant structure and function, along with the distinct body plan of seed plants. This quiz will test your knowledge on key plant organs and their functions.