Plant cells.pdf

Organelles of plant cells Mr. Heim Mengkhim B.Pharm Full Time Pharmacy Lecturer Faculty of Pharmacy University of Puthisastra Academic Year 2023-2024 11/5/2023 Mr. Heim Mengkhim...

Organelles of plant cells Mr. Heim Mengkhim B.Pharm Full Time Pharmacy Lecturer Faculty of Pharmacy University of Puthisastra Academic Year 2023-2024 11/5/2023 Mr. Heim Mengkhim B.Pharm 1 Content I. Overview II. The Cell Wall III. The Plasma Membrane IV. The Nucleus V. The Endoplasmic Reticulum VI. Ribosomes VII. Dictyosomes VIII.Plastids IX. Mitochondria X. Vacuole XI. The cytoskeleton 11/5/2023 Mr. Heim Mengkhim B.Pharm 2 I. Overview 11/5/2023 Mr. Heim Mengkhim B.Pharm 3 I. Overview Plant cells typically have a cell wall surrounding the protoplasm, which consists of all the living components of a cell. These living components are bounded by a membrane called the plasma membrane. All cellular components between the plasma membrane and nucleus are known as cytoplasm. 11/5/2023 Mr. Heim Mengkhim B.Pharm 4 I. Overview 11/5/2023 Mr. Heim Mengkhim B.Pharm 5 I. Overview Within the cytoplasm is a soup-like fluid called cytosol, in which various bodies called organelles are dispersed. Organelles are persistent structures of various shapes and sizes with specialized functions in the cell; most, but not all, are bounded by membranes (Figs. 3.4 and 3.5). 11/5/2023 Mr. Heim Mengkhim B.Pharm 6 I. Overview 11/5/2023 Mr. Heim Mengkhim B.Pharm 7 II. The cell wall Component of cell walls : Cellulose ( Main sturcutre) Hemicellulose Pectin and Glycoproteins Lignin Function : At the same time, the walls protect delicate cell contents within. 11/5/2023 Mr. Heim Mengkhim B.Pharm 8 II. The cell wall In addition to cellulose, cell walls typically contain a matrix of hemicellulose, pectin and glycoproteins. A middle lamella, which consists of a layer of pectin, is first produced when new cell walls are formed. 11/5/2023 Mr. Heim Mengkhim B.Pharm 9  II. The cell wall Reorganization, synthesis of new molecules, and insertion of new cell wall polymers lead to rearrangement of the cell wall during growth. Secondary walls, which are produced inside the primary walls, are derived from primary walls by thickening and inclusion of lignin, a complex polymer. Secondary cell walls of plants generally contain more cellulose (40% to 80%) than primary walls. 11/5/2023 Mr. Heim Mengkhim B.Pharm 10 II. The cell wall 11/5/2023 Mr. Heim Mengkhim B.Pharm 11 II. The cell wall 11/5/2023 Mr. Heim Mengkhim B.Pharm 12 III. The Plasma membrane The outer boundary of the living part of the cell called the plasma membrane. The plasma membrane and other cell membranes are composed of phospholipids arranged in two layers, with proteins interspersed throughout. 11/5/2023 Mr. Heim Mengkhim B.Pharm 13 III. The Plasma membrane 11/5/2023 Mr. Heim Mengkhim B.Pharm 14 III. The Plasma membrane Function Regulating the movement of substances into and out of the cell. Involved in the production and assembly of cellulose for cell walls. 11/5/2023 Mr. Heim Mengkhim B.Pharm 15 IV. The Nucleus Nucleus store of DNA Function Store information contributes to growth, differentiation, and the myriad activities of the complex cell “factory.” Proteins that act as channels for molecules are embedded within the pores which permit only certain kinds of molecules to pass between the nucleus and the cytoplasm. 11/5/2023 Mr. Heim Mengkhim B.Pharm 16 IV. The Nucleus The outer membrane of the nucleus is connected to and continuous with the endoplasmic reticulum. Extra point Chromatin : When a nucleus divides, the chromatin strands coil, becoming shorter and thicker, and in their condensed condition, they are called chromosomes. Chromatin is composed of protein and DNA 11/5/2023 Mr. Heim Mengkhim B.Pharm 17 IV. The Nucleus 11/5/2023 Mr. Heim Mengkhim B.Pharm 18 IV. The Nucleus 11/5/2023 Mr. Heim Mengkhim B.Pharm 19 VI. Ribosomes Ribosomes average only about 20 nanometers in diameter in most plant cells. Each ribosome is composed of two subunits that are composed of RNA and proteins. Function : linking amino acids together ( Translate of mRNA to Protein). 11/5/2023 Mr. Heim Mengkhim B.Pharm 20 VI. Ribosomes 11/5/2023 Mr. Heim Mengkhim B.Pharm 21 V. The Endoplasmic Reticulum Function :  Main function : Modification of proteins.  The endoplasmic reticulum facilitates cellular communication and channeling of materials.  Synthesis of membranes for other organelles 11/5/2023 Mr. Heim Mengkhim B.Pharm 22 V. The Endoplasmic Reticulum Rough ER : primarily associated with the synthesis, secretion, or storage of proteins. Smooth ER: is associated with lipid secretion. 11/5/2023 Mr. Heim Mengkhim B.Pharm 23 VII. Golgi apparatus Stacks of flattened discs or vesicles known as Golgi apparatus may be scattered throughout the cytoplasm of a cell. Function : modification of carbohydrates attached to proteins that are synthesized and packaged in the endoplasmic reticulum. 11/5/2023 Mr. Heim Mengkhim B.Pharm 24 VII. Golgi apparatus These vesicles migrate to the plasma membrane, fuse with it, and secrete their contents outside the cell. Substances secreted by vesicles may include  cell-wall polysaccharides,  and essential oils found in herbs 11/5/2023 Mr. Heim Mengkhim B.Pharm 25 VII. Golgi apparatus 11/5/2023 Mr. Heim Mengkhim B.Pharm 26 VIII. Plastids Chloroplast Within the chloroplast are numerous grana (singular: granum), which are formed from membranes and have the appearance of stacks of coins with double membranes. Thylakoids are part of an overlapping (ត្រួរល ើគ្នា) and continuous membrane system suspended in the liquid portion of the chloroplast. 11/5/2023 Mr. Heim Mengkhim B.Pharm 27  VIII. Plastids The thylakoid membranes contain green chlorophyll and other pigments. These “coin stacks” of grana are vital to life as we know it, for it is within the thylakoids that the first steps of the important process of photosynthesis. 11/5/2023 Mr. Heim Mengkhim B.Pharm 28 VIII. Plastids Chromoplasts Chromoplasts are another type of plastid found in some cells of more complex plants. Although chromoplasts are similar to chloroplasts in size, they vary considerably in shape, often being somewhat angular. They sometimes develop from chloroplasts through internal changes that include the disappearance of chlorophyll. 11/5/2023 Mr. Heim Mengkhim B.Pharm 29 VIII. Plastids Chromoplasts are yellow, orange, or red in color due to the presence of carotenoid pigments. They are most abundant in the yellow, orange, or some red parts of plants, such as ripe tomatoes, carrots, or red peppers 11/5/2023 Mr. Heim Mengkhim B.Pharm 30 VIII. Plastids Leucoplasts Leucoplasts are yet another type of plastid common to cells of higher plants. They are essentially colorless and include amyloplasts, which synthesize starches, and elaioplasts, which synthesize oils. If exposed to light, some leucoplasts will develop into chloroplasts, and vice versa. 11/5/2023 Mr. Heim Mengkhim B.Pharm 31 IX. Mitochondria Mitochondria (singular: mitochondrion) are often referred to as the powerhouses of the cell, for it is within them that energy is released from organic molecules by the process of cellular respiration. This energy is needed to keep the individual cells, and the plant as a whole, functioning. 11/5/2023 Mr. Heim Mengkhim B.Pharm 32 IX. Mitochondria They appear to be in constant motion in living cells and tend to accumulate where energy is needed. Mitochondria typically are shaped like cucumbers (ត្រសក់), paddles, rods, or balls. 11/5/2023 Mr. Heim Mengkhim B.Pharm 33 X. Vacuoles Vacuoles it has structure similar to plasma membrane. Function Maintenance of cell pressure and pH Storage of numerous cell metabolites Waste products. 11/5/2023 Mr. Heim Mengkhim B.Pharm 34 X. Vacuoles 11/5/2023 Mr. Heim Mengkhim B.Pharm 35 XI. The Cytoskeleton The cytoskeleton is involved in movement within a cell and in a cell’s architecture. It is an intricate network constructed mainly of two kinds of fibers— microtubules and microfilaments. Microtubules Unbranched, thin, hollow, tubelike structures Composed of proteins called tubulins Control the addition of cellulose to the cell wall Involved in cell division, 11/5/2023 Mr. Heim Mengkhim B.Pharm 36 XI. The Cytoskeleton Microfilaments Play a major role in the contraction and movement of cells. Facilitates exchanges of materials within the cell Role in the movement of substances from cell to cell. 11/5/2023 Mr. Heim Mengkhim B.Pharm 37 XII. References 1. Stern’s_Introductory_Plant_Biology_James_E_Bidlack,_Shelle y_H_Jansky. 2. Botany - An Introduction to Plant Biology (James D. Mauseth) (z-lib.org). 11/5/2023 Mr. Heim Mengkhim B.Pharm 38