Plant Cell structure and Function

Plant Cell is a eukaryotic cell (Eu: true; karyo: nucleus), therefore with true nucleus. The genetic material, DNA is surrounded by a nuclear membrane. Membrane bound organelles like chloroplast, mitochondria, SER, RER etc. are also present.

1. Nucleus (Controlling center of the cell): is a double membrane bound organelle where DNA is present. It is the site where DNA; the hereditary material is found which controls the activities of the cell. It consists of a nuclear membrane or envelope with pores, the nuclear sap or nucleoplasm, chromatin fibres (DNA) and nucleolus. Detailed notes on Nucleus

Nucleolus: Nucleolus are membrane less prominent spherical colloidal bodies rich in RNA present in the nucleus.

Function: It is the site where ribosomal subunits, 40S and 60S are synthesized Detailed notes on Nucleolus

2. Rough Endoplasmic reticulum (RER): RER consists of interconnected network of membrane vesicles studded with ribosomes. On the membrane of RER, ribosomes are attached to transmembrane glycoproteins called ribophorins I and II.

Function: synthesis of secretory and membrane proteins and post translation modification (protein glycosylation) Detailed notes on ER

3. Smooth Endoplasmic reticulum (SER): interconnected network of membrane vesicles without ribosomes; that’s why called “smooth”.

Function: lipid biosynthesis including cholesterol and phospholipid synthesis and drug detoxification

4. Vacuoles: Often the largest organelle in a plant cell, bounded by a single membrane called tonoplast.

Function: Vacuoles play a major role in autophagy, maintaining a balance between biogenesis (production) and degradation of many substances and cell structures. They also aid in destruction of invading bacteria just like lysosome in animal cells

Detailed notes on vacuole

5. Golgi apparatus (GA): Consists of parallelly arranged flattened membranous sacs that lacks ribosomes. Proteins synthesised in the RER pass through different regions of golgi apparatus (cis, median and trans golgi) where it undergoes further modification.

Function: GA is the sorting centre of the cell. In plant cells, GA is involved in the deposition of primary and secondary wall materials (pectin, cellulose etc).

Detailed notes on GA

6. Ribosome 80S: are made up of several rRNA molecules and ribosomal proteins, simply an RNA-protein complex. Both free ribosomes in cytoplasm and attached ribosomes in RER are present.

Function: Protein synthesis. Detailed notes on ribosomes

7. Mitochondrion: semi-autonomous, double membrane bound organelle with DNA

Function: ATP synthesis through cellular respiration; therefore, called as “power house of the cell”, beta oxidation in matrix. Detailed notes on Mitochondrion

8. Chloroplast: semi-autonomous, double membrane bound organelle with DNA. Grana is the site of light dependent reaction whereas stroma is the site of light independent reaction or Calvin cycle.

Function: photosynthesis; also involved in photorespiration Detailed videos on Photosynthesis

9. Peroxisome: are microbodies or self-duplicating, single membrane bound organelles present in all eukaryotic cells. They contain oxidative enzymes, such as catalase and urate oxidase, at such high concentrations.

Function: compartment for oxidation reactions, H₂O₂ scavenger; chemical detoxification, lipid synthesis, producing two phytohormones: IAA and JA, photorespiration Detailed notes on peroxisome

10. Cytoskeleton: made up of microfilaments, intermediate filaments and microtubules; also called as “cytomusculature”.

Function: structural frame work of the cell, involved in growth and development, cell division, cell expansion, and intracellular organization. Detailed notes on cytoskeleton

11. Plasma membrane: selectively permeable membrane made up of phospholipid bilayer and proteins

It encloses the interior of the cell, regulating the flow of materials in and out of the cell. Detailed notes on plasma membrane

12. Cell Wall: made up of cellulose, hemicellulose & pectin

Function: mechanical support, providing shape to the cell. Detailed notes on Cell wall

Plant Cell structure and Function

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