Plant Cell and Ergastic Substances Lecture Notes (PG 111) - Mansoura University PDF

1st level pharmacy students PG 111 Lecture 2: Plant cell and ergastic substances By : Dr. Abdullah Haikal Lecturer in Pharmacognosy Department, Faculty of Pharmacy, Mansoura University Mansoura Univer...

1st level pharmacy students PG 111 Lecture 2: Plant cell and ergastic substances By : Dr. Abdullah Haikal Lecturer in Pharmacognosy Department, Faculty of Pharmacy, Mansoura University Mansoura University - Faculty of Pharmacy - PG 111 Plant Anatomy ‫عمل ترشحي النبات‬ Plant anatomy describes the structure and organization of the cells, tissues and organs of plants in relation to their Organs development and function = Tissues the study of plant cell and tissue structure Cells Mansoura University - Faculty of Pharmacy - PG 111  Cell Structure and Function  All living things are made up of cells.  Cells are the smallest working units of all living things. Definition of Cell: A cell is the smallest unit that can perform life functions. Mansoura University - Faculty of Pharmacy - PG 111 Typical Plant cell Mansoura University - Faculty of Pharmacy - PG 111 Mansoura University - Faculty of Pharmacy - PG 111  A Typical plant cell a) Polyhedral cells with rounded angles. b) Wide lumen. c) Without intercellular spaces. Mansoura University - Faculty of Pharmacy - PG 111  Each cell consists of living and non-living materials. Plant cell has three regions 1- The cell wall (Non-living) 2- The protoplast (Living) 3- The vacuoles (Non-living) 1-Cell wall  Is semirigid, external, non-living.  Present in plant cell but absent in animal cells.  It give protection and support, covering the living plasma membrane.  A fundamental difference between plant and animal cells is that the plant cell is surrounded by a rigid cell wall, mostly made of polysaccharides (cellulose, hemicellulose, pectin) and lignin. Mansoura University - Faculty of Pharmacy - PG 111 Cell wall is distinguished into three parts: 1- Middle Lamella 2- The primary cell wall 3- The secondary cell wall Cell #1 Cell #2 middle lamella plasma primary cell wall membrane (cellulosic) secondary cell wall (lignified) pit primary pit field (pits of two adjacent (collection of several cells = pit-pair) plasmodesmata) plasmodesmata Cell #1 Cell #2 Mansoura University - Faculty of Pharmacy - PG 111 1- Middle Lamella  It is the first partition arises between two cells.  It made up of mostly of calcium and magnesium pectate. 2- The primary cell wall  This second layer consists mainly of cellulose molecules.  It capable of extension as the cell grows. 3- The secondary cell wall  When the cell ceases to enlarge, the protoplast secretes additional substances on the inner of the primary wall, in the form of successive layers. These layers consists mainly of cellulose, hemicellulose, lignin and suberin.  In supporting cells as fiber and vessel cells.  The secondary wall differs from the primary walls in that it is incapable of increase in area. Lignified elements stained red upon application of phloroglucinol solution in the presence of hydrochloric acid Mansoura University - Faculty of Pharmacy - PG 111  Pits and plasmodesmata  Most cells have thin areas in the primary walls (no secondary wall layer), which have small pores through which strands of cytoplasm (plasmodesmata) connect the protoplasm of one cell with that of the adjacent cell.  Plasmodesmata aid in the movement of materials and transmit stimuli. Mansoura University - Faculty of Pharmacy - PG 111  Pits A pit is a region in the cell wall in which no secondary wall is deposited.  There are three types of pits: 1- Simple 2- Bordered 3- Half-bordered Simple pits: may be found in certain parenchyma cells, in phloem fibers and in sclereids. Bordered and half bordered pits: occur mainly in the conducting and mechanical cells of xylem such as vessels and tracheids. Mansoura University - Faculty of Pharmacy - PG 111 Mansoura University - Faculty of Pharmacy - PG 111  Plant cell has three regions 1- The cell wall (Non-living) 2- The protoplast (Living) 3- The vacuoles (Non-living) 2-Protoplast  The protoplast, consisting of the plasma membrane and all inside of it except any non-living materials as crystals, starch grains and contents of the vacuoles.  The protoplast is surrounded by a delicate membrane (the plasma membrane) and include two major components (the cytoplasm and the nucleus). Mansoura University - Faculty of Pharmacy - PG 111 A- The plasma membrane  Bilayer of phospholipid (polar head & nonpolar tail).  Proteins embedded and adhered to the surface.  The lipid molecule consists of a fatty acid tail (lipophilic) and a head (hydrophilic), the fatty acid tails face towards the inside and the hydrophilic heads outwards to the outer protein layers. Functions of plasma membrane: 1- protection of the cell. 2- It is selectively permeable and regulates the movement of molecules in and out of the cell. 3- Sensory transduction ‫نقل االحساس‬, i.e., the sensing and initiation of the cellular response to the changed environmental conditions. 4- Act as a source of information of various kinds and synthesis of some macromolecules. Mansoura University - Faculty of Pharmacy - PG 111  B- The cytoplasm The cytoplasm appears as a semi fluid in which the organelles and cell inclusions are found. 1- Nucleus (Leader of the cell)  Large spherical structure enclosed by an envelope of two membranes that is perforated by nuclear pores. A net work of chromatin fibers (extended chromosomes) and a nucleolus are present inside.  The chromatin material includes Deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and proteins. Function: The nucleus controls all the activities of the cell and the transmission of hereditary characters ‫الصفات‬ ‫الوراثية‬. Mansoura University - Faculty of Pharmacy - PG 111 2- The Endoplasmic reticulum ‫الش بكة الإندوبالزمية‬ Two types of ER are known: - Smooth ER lacks ribosomes & makes proteins USED in the Cell and synthesis of lipids and phospholipids. - Rough ER has ribosomes on Its surface & makes proteins to EXPORT. Function of ER 1- Forming the skeleton of the cell. 2- Translocation of various substances. 3- Protein and fat synthesis. 4- Helping in keeping certain enzymes and metabolites separate. Mansoura University - Faculty of Pharmacy - PG 111 3- Ribosomes  They are minute, rounded to spherical bodies.  They are composed of RNA and protein.  They are characterized by their high protein synthesis ‫تصنيع البروتين‬. 4- Golgi apparatus  Stacks of flattened sacs. ‫أأكوام من الأكياس املسطحة‬ Function: Its function is: packaging and secretion of proteins. It receives proteins from ER. It packages it into membrane-bound vesicles, which are then transported to various destinations. Both Golgi apparatus and ER are responsible for cell wall formation. Mansoura University - Faculty of Pharmacy - PG 111 5- Mitochondria It consists of two Membranes 1- The outer membrane: Which is continuous and encloses a central space. 2- The inner membrane: Sends folds into their central space which are called cristae. The mitochondrial inner chamber is filled with homogenous matrix. Function of mitochondria.  It is called “the powerhouse of the cell” because they produce much of the energy necessary for the cell to carry out their functions.  Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP). Mansoura University - Faculty of Pharmacy - PG 111 6- Plastids [ in plant cells only] According to their pigmentation, they are distinguished into three types: 1- Leucoplasts 2- Chromoplasts 3- Chloroplasts a- Leucoplasts  They contain no chlorophyll and are known as colorless plastids. b- Chromoplasts  They do not contain chlorophyll but contain carotenoid pigments and appear as colored plastids. e.g., carrot and tomato. Mansoura University - Faculty of Pharmacy - PG 111 c- Chloroplasts  They contain chlorophyll.  The chloroplast is surrounded by two membranes.  Chloroplast contains stacks of flattened organelles called a thylakoid. One stack of thylakoids is called a grana. Grana float within a cytoplasm- like fluid in the chloroplast called stroma. Function of chloroplasts: It is the organ for photosynthesis. The sunlight is trapped and converted to chemical energy in grana. Mansoura University - Faculty of Pharmacy - PG 111 7- Lysosomes These are simple spherical sacs bounded by single membrane and contain digestive enzymes. Function: Intracellular digestion. Mansoura University - Faculty of Pharmacy - PG 111  Plant cell has three regions 1- The cell wall (Non-living) 2- The protoplast (Living) 3- The vacuoles (Non-living) 3-Vacuoles Mature cells of the plants have vacuoles which may enlarge to much an extent that the cytoplasm located adjacent to the cell walls. The vacuoles are filled with cell sap. It is surrounded by lipoprotein membrane (Tonoplast). The vacuole may contain pigments as anthocyanin Mansoura University - Faculty of Pharmacy e.g., Colored petals. - PG 111  Ergastic substances (Cell inclusions)  The materials present in the vacuoles are known as ergastic.  They are either reserve substances that may be utilized by the protoplast, for vital activities or they are by-products of metabolism.  Ergastic substances occur in the vacuoles and in the cell wall. Mansoura University - Faculty of Pharmacy - PG 111  Ergastic substances (cell inclusions) (cell contents) The materials present in the vacuoles are known as ergastric. They are either reserve substances that may be utilized by the protoplast, for vital activities or they are by-products of metabolism. Ergatric substances occur in the vacuoles and in the cell wall, and may be associated with the protoplasmic components of the cell. They are of two types:- (1) Food-storage products (carbohydrates, proteins, fixed oils and fats). (2) Waste products (they are excretion of plant cells formed as a result of metabolic activities of protoplasm, i.e. by-products of metabolism). Mansoura University - Faculty of Pharmacy - PG 111  Food-storage products (A) Carbohydrates (cellulose and starch) Cellulose is the main constituent of the cell wall, where as starch occurs as reserved materials in the protoplast. Both are composed of long chain of glucose units. Mansoura University - Faculty of Pharmacy - PG 111 Starch is usually found in the form of granules of various shapes which may be for the plant type and used for its identification. Acid hydrolysis of starch gives glucose while hydrolysis with β- amylase enzyme yields maltose. Mansoura University - Faculty of Pharmacy - PG 111 1- Starch Mansoura University - Faculty of Pharmacy - PG 111  Maize starch Characters: 1- Rectangular in shape with rounded angles. 2- Centric hilum. 3- Cleft or fissured hilum. Mansoura University - Faculty of Pharmacy - 4- No striation. PG 111  Potato starch Characters: 1- Oval or rounded in shape 2- Eccentric hilum. 3- Dot hilum. 4- Have striations. Mansoura University - Faculty of Pharmacy - PG 111  Tests for identity I. Microscopic examination: to detect the source of starch: maize, rice, potato and wheat starch. II. Iodine test: starch gives blue color with iodine solution. Mansoura University - Faculty of Pharmacy - PG 111  (B) Proteins form They are complex organic nitrogenous substances. They consist of carbon, hydrogen, oxygen and nitrogen. A Protein molecule is made up of hundreds or thousands of amino acid molecules linked together by peptide linkages. Proteins are frequently found in plants as reserve food materials in the form of solid granules known as aleurone grains. Mansoura University - Faculty of Pharmacy - PG 111 2- Protein  Proteins are stored as aleurone grains.  Proteins are polypeptide of amino acids.  Aleurone grains are stained red with Millon reagent, yellowish brown with iodine solution and yellow with picric acid, leaving the globoids unstained. Mansoura University - Faculty of Pharmacy - PG 111 A typical aleurone grain consists of an amorphous ground substance enveloped by a thin protein membrane, and in which are embedded one or more angular bodies called crystalloids and one or more colourless globular bodies termed globoids. The crystalloid occupies the major portion of the granule while the globoid occupies the narrower part. Mansoura University - Faculty of Pharmacy - PG 111 Aleurone grains are stained red with Millon‫׳‬s reagent, yellowish brown with iodine solution, yellow with picric acid, leaving the globoids unstained. Mansoura University - Faculty of Pharmacy - PG 111  (C) Fixed oils and fats They are mixtures of esters of fatty acids and the trihydric alcohol; glycerol, usually called glycerides, triglycerides or glyceryl esters. They are of two types: Solid: wax, suberin, fat and cutin. Liquid: fixed oils. They are coloured Brown or black with a 1% solution of osmic acid. Red with Suddan III and dilute tincture of Alkana. Mansoura University - Faculty of Pharmacy - PG 111 3- Fats o Esters of fatty acids with glycerol. o They widely in the plant body. o Lipids and oil may be as liquid fats. o Wax, suberin and cutin are fatty in nature. They act as a protective substance in and on the cell wall. Mansoura University - Faculty of Pharmacy - PG 111 Volatile (essential) oils They are usually mixtures of organic compounds as hydrocarbons, alcohols, aldehydes, ketones, esters, etc. The volatile oils frequently occur as droplet in oil cells, oil glands or glandular trichomes, and are usually very odoriferous. Mansoura University - Faculty of Pharmacy - PG 111  Waste products Calcium carbonate crystal Mansoura University - Faculty of Pharmacy - PG 111  Calcium oxalate crystals They are very common cell content in the plant kingdom and may function to deter herbivores from eating plant parts. They are nature's way of discouraging animals and other pests from eating these plants. Mansoura University - Faculty of Pharmacy - PG 111 3- Crystals ‫البلورات‬ Mansoura University - Faculty of Pharmacy - PG 111 The most common forms may be grouped into: Prisms (Square, rhomboidal or pyramid-like prismatic crystals) Mansoura University - Faculty of Pharmacy - PG 111 Raphides. Acicular (needle-shaped) crystals Mansoura University - Faculty of Pharmacy - PG 111 Clusters They are widely distributed and formed of aggregated prisms Mansoura University - Faculty of Pharmacy - PG 111  How to differentiate ??? Calcium oxalate crystals are insoluble in acetic acid but dissolve in hydrochloric and sulphuric acid without effervescence (c.f. Calcium carbonate). Mansoura University - Faculty of Pharmacy - PG 111 1- A rigid plant cell wall, mostly made of ………. A- lignin B- polysaccharides C- (A and B) D- None of the above 2- Organelle in the cell that is responsible for cell wall formation ………. A- Golgi Apparatus B- Lysosomes C- Mitochondria D- Nucleus Mansoura University - Faculty of Pharmacy - PG 111  3- Which of the following is nonliving? A- nucleus B- plasma membrane C- mitochondria D- vacuole 4- Lignified elements stained ……. upon application of phloroglucinol solution in the presence of hydrochloric acid A- blue B- red C- green D- yellow Mansoura University - Faculty of Pharmacy - PG 111 Study the opposite figure and complete the following table: Layer name Chemical composition Black layer ……………… ……………… ……… ……… Red layer ……………… ……………… ………. ………… Grey layer ……………… ……………… ………… …………. Mansoura University - Faculty of Pharmacy - PG 111 Complete the following: 1-The opposite figure represent …………………. Which composed of …………………………….. 2- The cytoplasm like fluid inside the opposite structure called ……………. 3- The function of the opposite organelle is …………………………………. Mansoura University - Faculty of Pharmacy - PG 111 Q: Complete the followings:  Cystolith is composed mainly of ……………………………….and soluble in………  Aleurone grains are stained red with ……………………………  Hydrolysis of starch with β- amylase enzyme yields...............................  1% solution of osmic acid gives a brown or black color with…………………………....  A carbohydrate used as a building material in the formation of cell wall is …………….  CaOX crystal is soluble in …………………………………….  Aleurone grains are stained …………………………………..with picric acid. Mansoura University - Faculty of Pharmacy - PG 111 Mansoura University - Faculty of Pharmacy - PG 111