General Botany

                                         General Botany\\

 

                       Technical College of Agriculture In Mosul

        First year students…Department Of Agricultural  Techniques

               Fall Semester………By : Dr. Mohammad Alhadeedy.

Botany:

The science of studying plants from different aspects like initiation, growth regeneration, benefits, disadvantages and every other activities of plants  and their distribution.

• There are many branches of this science related to botany such as:
• Anatomy, biogeography, cytology, ecology, evolution, embryology, histology, pathology, physiology, taxonomy, genetics or heredity, morphology, economical biology and at last paleontology.

There are five kingdoms in general these are:

1-Animalia.

2-plantae.

3-Fungi.

4-Monera.

5-Protista.

Kingdom Monera

During 1866 the German scientist Emst Haekel discovered a bacteria and he called it (moneres in german language). The term is derived from the greek noun moneres which mean simple or it mean singular or solitary.

The monera include two groups these are:

• Blue green algae (Division cyanophyta)
• Bacteria (Division schizophyta)

It include all organisms with prokaryotic cells which have no nucleus. For this reason the kingdom is called sometimes prokaryota or prokaryotae. It is believed that bacteria was one of the first forms of life on earth.

Importance of monera:

They are important to the total ecological system of the world. They recycle complex materials by decoposition and making them utilizable by other organisms.

Note that 99% of the bacteria are not harmful.

Characteristics of the division cyanophyta

Blue –green algae:الطحالب الخضراء الزرقاء

1.they  consist of one cell either single or in colonies.

2. The pigments are located in the peripheral region of the cell, while the genetic DNA is in the central region.
3. Chlorophyll (a) is usually masked by a blue pigment (phycocyanin) While a red pigment (phycoerythrin) is present in the cells of some species.
4. The stored food is mainly cyanophyte starch similar to the glyogenfound in many nimals.

5.reproduction is by simple division.

6.the cells and colonies are filamentous enclosed by a slimy gelatinous sheath.

7. Few species form resistant spores called (Akinetes) but this is not a method of reproduction.
8. They are widely distributed and are either aquatic or living on damp surfaces. They live in hot springs(hot water) of up to 80 .

9.Cyanophyta can fix nitrogen in the soil and are capable of utilizing  N.

Characteristics of the division schizophyta (Bacteria):

1. They are unicellular plants.
2. They lack chlorophyll so they are largely heterotrophic.

3.some bacteria contain pigments similar to chlorophyll (a) and are photosynthetic .

4. Some bacteria are chemosynthetic (autotrophs).
5. The bacterial size range between 0.5 – 3.0 in diameter (1 = 1/10000 cm )

6.some bactria are aerobic which means using air  to live ., others are anaerobic i.e (id est ) which mean that they  don’t need air.

7. Have different shapes such as COCCUS or sphere or bacillus (rods) or spirillum (spirals), they may join each other to form chains or colonies
8. Bacterial cells may produce one spore each which germinate to produce one cell under favorable conditions.
9. Some bacteria may divide under suitable conditions once every 30 minutes which would result in Cells during a month weighing 1500 tons.
10. Some bacteria can cause diseases to man such as plague, cholera and typhoid fever.
11. bacteria have some advantages such as decomposition of organic materials as sewage dispersal or food processing such as cheese.
12. Some bacteria can fix nitrogen such as azotobacter (nitrobacter) in legumes, examples faba beans and peas.

Kingdom Protista:

Definition:A group of organisms made up of a heterogenous متغاير المنشأ assemblage of unicellular,colonial and multicellular eukaryotes. It include protozoans, slime molds, brown algae,red algae, diatoms (a kind of algae) and oomycetes a nonphotosynthetic fungi resemble algae and reproduce by oospores). The term protista means the very first from protos which means first. Or most primitive organism.

They live in water or watery tissues. Some produce their food by photosynthesis, while others consume their food like animals.

Characteristics of protists:

1- They can be heterotrophic or autotrophic.

2- They live in water or moist soils or human body.

3- All are eukaryotic(have nucleus).

4- A protozoa Mostly unicellular, others are multicellular(algae).

5- Protist is any organism that is not a plant or animal or fungus.

Protists are grouped into three categories, these are:

1. Protozoa: الابتدائيات These are animal like especially in nutrition. They ingest their food by phagocytosis البلعمة some have mouth- like structure to prey. While others use pseudopodia to engulf bacteria and single cell organisms such as amoeba.
2. Algal protists: They are photosynthetic (plant-like), almost all of them have chlorophyll (A) and some have chlorophyll (C) and few have chlorophyll (B). they possess a variety of carotenoids and other pigments. So they are listed into the following groups:

a- Dinoflagellata, دوامية السياط example Euglena.

b- Chlorophyta,  طحالب خضراءthey are called green algae e.g chlamydomonas, has chlorophyll) ,and volvox , spirogyra and clostridium.

c- Phaeophyta: طحالب بنية called brown algae which contain iodine, example Laminaria used to make pudding and salad dressing.

d- Rhodophyta طحالب حمراء known as red algae. They are multicellular many are used as food such as Nori which is used in sushi Japanese food.

3. +Fungal- Like protists: Myxomycota: البدائيات الشبيهة بالفطريات These are called slime molds, فطريات مخاطية they are fungus-like in nutrition. They absorb their food from their environment. They move like amoeboid movement. They live on decayed wood and they possess yellow or orange colour. Example (e.g. examplei gratia وتعني مثلا باللاتينية ( :

a-Water molds: which live in moist environments like threads.

b- Downey mildews: = =    =      =       =          =            =     =           .

c-Slime molds :            =        =      =       =         =           =      =          .

Phycology or Algology

Euglena

Euglena gradilis: Is a genus of unicellular flagellate protist. It is a pear-like shaped and is like a plant and animal. It is used as a laboratory model for study. It is a member of the phylum euglenozoa or euglenophyta. It contain 44 genera and 800 species. They live in salt and fresh waters.they cover the surfaces of ponds and ditches with green color, such as:

Euglena viridis, or red in case of Euglena sanguinea.

Euglena was dicovered by the deutch scientist Antony van Leeuwenhoek in 1674 A.C. from an inland lake water samples.

 

 Classification of euglena:

Domain                                                Eukaryota

Kingdom                                              protista

Superphylum                                      Discoba

Phylum                                                 Euglenozoa

Class                                                      euglenoidea

Order                                                    Euglenales

Family                                                  Euglenaceae

Genus                                                  Euglena

 

Euglena protoplast contain pyrenoids which is a kind of starch stored as a source of energy.

 

                      Characteristics of euglena:

 

1. Most euglena species have chloroplasts to synthesize their food, others are feeding like animals.
2. The eye spot contain carotenoid pigment granules.
3. They lack a cell wall but they have a pellicle made up of a protein layer.
4. When food is scarce or there is a low moisture conditions, they would form a protecting layer or wall around themselves and stay dormant until the conditions improve.
5. They move by flagella.
6. They reproduce by binary fission lengthwise. The flagellum goes with one part, while the other part grows a new flagellum.
7. They have contractile vacuoles to drive out excess water.

 

Benefits of euglena:

 

1. They form benthic mats in acid mine drainage associated with coal mining activities.
2. Have a significant effect on the pH of mining drainage and the concentration of dissolved iron and other hazardous metals in the environment.
3. Euglena is used to produce foods and cosmetics. They contain five kinds of nutrients such as: vitamins, fatty acids, minerals such as {zn,p, Ca,Mg}. and amino acids.
4. Euglena contain antioxidants, decreasing cholesterol, colon cleaner, and help the body to absorb necessary nutrients.

 

Reproduction of euglena:

A sexual reproduction occur in euglena called binary fission which include mitotic division. The chromosomes split in the nucleus as a thread-like strands of DNA , then the nucleus separate into two sets  of identical chromosomes to form two  separate nuclei which lead to form two daughter cells genetically identical with the parent.

The chloroplast and basal bodies divide into halves ,and the entire organism separate down the middle, followed by division of  the cytoplasm into two daughter cells.

There are three types of divisions in euglena:

1. simple division :(cytoplasmic division passes through any plane).
2. Transverse division: The plane of cytoplasmic division coincides with the transvers axis of the organism.
3. Longitudinal division: called binary fission, the plane of cytoplasmic division coincides with the longitudinal axis of the organism.

Fungi:

 

Definition: The fungi constitute a large and diverse groups of non chlorophyllous simple plants. They are filamentous. The single filament is termed hypha, and a group of hypha is termed mycelium. They are heterotrophic.

The major component of the cell wall is chitin which is a polysaccharide. Fungi live everywhere in the air, land, soil, plants and animals.

Classification: example Rhizopus

Kingdom                           Fungi

Pyhlum Zygomycota

Class                                  Zygomycete

Order                                mucoratis

Family                              mucoraceae

Genus                              rhizopus

Species                            stolonifer

 

Characteristics of Fungi:

1. Some are parasitic on living hosts.
2. The cell wall is made of chitin.
3. Reproduce sexually and a sexually.
4. The stored carbohydrate (CHO) is glycogen found in animals.

 

Mushroom

Agaricus bisporus

Any of various fleshy fungi of the class basidiomycota having an umbrella shaped cap, born on a stalk. It is an edible kind of the genus agaricus. It has a spore bearing gills underside the umbrella. They live above and underground.

The white mushroom A. bisporus is the most widely distributed in the world due to its low temperature requirements. So it could be grown in the cool regions of the world. It is known as snow white mushroom, which first appeared amongst a bed  of mushroom in the USA and ever since the variety has dominated the mushroom industry throughout the world., although it  has a very limited shelf life.

There are 20 species of edible mushrooms commercially cultivated such as:  Agaricus bisporus oyster mushroom Pleurotus spp. Crimini (brown mushroom)……etc.

China is the leading country in mushroom production around the world. There are 38000 species of mushrooms, only 3000 spp. Are edible, and 700 spp. Of them have medicinal properties. Some others are poisonous.

Mushroom Culture or cultivation:

 

The best strain should be collected which should be high yielding, visually attractive, with desirable flavor, and disease resistance. Three methods are known for strain propagation, these are:

1. Multipurpose culture.
2. Tissue culture: small pieces of fruit bodies are cut under sterile conditions and inoculated 0n a nutrient medium. The mycelium growing out of these tissues can provide the spawn.
3. Mycelium transfer is most reliable it is continually checked out to detect any degeneration ( decay) like slow growing , matted mycelium,or fluffy mycelium with abnormal growth rate.

Spawn:

Is the propagating material used by the mushroom growers for planting beds. It is equivalent to vegetative seed of higher plants. The spawn quality is basic for successful mushroom cultivation.

There are three ways to prepare spawn these are:

1. Grain spawn.
2. Manure spawn. Perlite spawn.

Grain spawn: To prepare the grain spawn we have to achieve the following steps :

1.Take 10 kilograms (kg) of wheat grains and boil for 15 minutes. Allow to soak for another 15 minutes.

2.Drain the excess of water and cool the grains down in sieves.

3. Mix the grains with 30 grams (gm) of calcium carbonate and gypsum CaCO₃ and gypsum CaSO₄.2H₂O .The gypsum prevent sticking of grains while calcium carbonate is necessary to correct the pH.
4. The separated grains are filled into half Litre milk bottles or polypropylene bags at the rate of 150- 200 gm./bottle or bag.

5- Put in the autoclave for two hours at 121 C for sterilization. The pH

Should be 6.5-6.7  after that.

6– Inoculate the bottles or bags with grain spawn or bits of agar medium colonized with mycelium, and incubate at 22-24 C  in a dark place.The mycelium completely permeates يتخلل او يخترق the grains in about two weeks.

Note: (N.B.) Nota bene:وتعني ملحوظة other grains are used for spawn production such as pear millet and sorghum.

                            Procedure for spawn preparation:

1.Prepare the workplace by sterilizing the area with 10  bleach water solution and prepare your (HEPA) (high efficiency particulate air filter)or laminar air flow hood.

2. 2. Sterilize all the tools used in the work using the autoclave at 93 C˚ and pressure of 15 Psi(Pound per squared inch) for 45 minutes.
3. 3. To make a spawn place a small piece of mushroom on an agar medium petri dishes and keep it moist at suitable temperature. The mycelium will grow out and fill the dish within about two weeks.
4. 4. Transfer the mycelium when it fill the petri dishes to the sterilized grains in jars, and allow to colonize for about 2-4 weeks under proper temperature.
5. 5. Watch the Jars, when they are filled with healthy white filaments which means that you have achieved grain spawn. Mushrooms will grow right out of the jar and you can use it to inoculate more grains, as one jar of grain spawn can produce up to ten more.

6.spread the spawn around the medium like compost or strawto obtain more production of mushrooms within two weeks through the  medium.

 Benefits of mushrooms:

1. Mushrooms are rich in fibers with cholesterol loweringmaterial (chitin)and beta glutan for healthy hearts.
2. Provide a high quality protein, vitamins, unsaturated fatty acids and minerals such as: Fe, P, K, and low calorie dietary.
3. Medicinal mushrooms boost heart health, lowering risk of cancer,promote immune functions, reduce inflammations caused by bacteria or fungi or viruses, reduce allergy and help to balance blood sugar.

There are three main famous medicinal mushrooms ,these are:

1. Maitake: for cancer and diabetes, stomach and intestines.

• Reishi: for asthma.

1. Shiitake: for heart diseases, AIDS (Acquired Immune deficiency Syndrome), colds ,flu,nutrient deficiencies and other ailments.
2. Lowers blood pressure and anticancers such as: crimini mushroom and button mushroom which has a brown colour.
3. They are antiviral.
4. Rich in several antioxidants such as selenium, uric acid and vitamins A, E, C, D.
5. Help to increase Libido.القوة البيولوجية
6. Give flavor to food such as soups and salads or used as an appetizer.
7. Boost يدعم أو يشجع immune system functioning.
8. Boost cardiovascular health, e.g. (Crimini mushroom).
9. Restore the body balance and natural resistance against diseases.
10. Mushrooms are analgesic مسكن للألم with anti inflammatory properties.
11. Mushrooms are low calorie foods used for dietry (reducing weight).

Example of classification of rose plant:

The Plant Kingdom:

Subkingdom Embryophyta

Division anthophyta

Class Dicotyledonae

Order Rosales

Family Rosaceae

Genus Rosa

Species Rosa setigera

Variety

 

Scientific names and Binomial Nomenclature:

The scientific name consist of two words, the first one refers to the genus and the second refers to the species .example :Pisum sativum and  Vitis vinifera. The genus should start with a capital letter , and the two words should be underlined or written in italic letters such as: Euglena gradilis and Rosa setigera. The type of name could be related to the botanist who discovered the organism whether it is a plant or animal. Or related to the region of living such as Canadensis virginiana from Virginia state or belong to the color of the plant or part of it example; Morus alba and Morus rubra with a capital letter at the end which refers to the name of the botanist who gave the scientific name such as the sweedish botanist Linnaeus (1707—1778 A.C). who put the modern system for nomenclature. Example:

• Prunus persica. L. The first letter of the name of the scientist is written at the end of the botanical name.

 

The vascular plants (tracheophyta):

 

Definition: Plants which possess a well developed vascular system that serves for the conduction of water, mineral salts and foods. Most of them are land plants while some require free water for fertilization. They have xylem and phloem and called higher plants. There are four phyla  of vascular plants, these are:

1.Psilophyta  .

2.Lycophyta.

3.Sphenophyta

4.Pterophyta.

The Phylum pterophyta is by far the largest for it include all the ferns, shrubs and herbs which dominate the present vegetation. It is divided into three classes: 1. Filicinae or ferns example: (Onoclea sensibilis ).

2. Gymnospermae: include conifers and related plants, example: (pine). The most known members are the conifers and all of them produce seeds so they are of economical importance.
3. The angiospermae or flowering plants such as (apple). They include an important and economical plants ( flowering plants) which at present form  the dominant flora. They produce flowers which develop seeds and fruits at the end. It is important to note that seeds are born within a closed structure called the ovary.

Characteriticsof flowering plants:

1. The reproductive organs are flowers but not cones.
2. Pollination is by insects or wind or water.
3. They form a fertilization tube through the style to the ovary
4. Double fertilization occurs to form the zygote and the endosperm.
5. The conducting system in the flower plants is by vessels found in the xylem tissue.
6. The phloem consist of sieve tubes and companion cells.

Double fertilization in anthophyta:

 

The following stages are going to take place during this process:

1. A diploid microspore mother cells are formed in the anther. Meiotic division occur to form four haploid microspores (male spores) which will separate of each other.
2. The nucleus of the small spore (microspore) undergoes mitotic division forming a tube cell and a generative cell .This represent the pollen grain,which is transferred by wind or insects to the stigma of the flower to germinate forming the pollen tube down to the ovary.

3. The generative cell divides to form two sperm cells, one of them will unite with the egg to form the zygote , while the second one unite with the polar nuclei to form the endosperm in the angiosperms, and it is triploid. It is a nutritive embryonic tissue to feed the embryo.
4. The carpels contain ovules, and there is a megaspore mother cell formed inside the ovule. This cell undergoes meiotic division to produce four monoploid megaspores (female spores). Three of them disintegrate and only one persist to form the embryo sac, which contain eight nuclei three are antipodal cells at one end and two polar nuclei in the middle and the egg cell at the other end with two synergid cells beside it.
5. Some plants produce seeds without an endosperm and occupied with a big embryo, while other plants produce seeds containing an endosperm and small embryo.
6. The transition of ovules into seeds at maturity is accompanied with the revolution of the ovary into fruit, and at the end the fruit will contain one seed or more inside, protected by the fruit tissue. If the endosperm is been absorbed during the seed formation, then the cotyledon become the essential organs for food preservation.
7. The angiosperms include two groups of plants these are:

A –Class: monocotyledons:

The seed is made of only one cotyledon, examples: wheat, barley, sorghum, oats and rice, which are all herbaceous plants. Other monocots are woody trees such as date palms and bamboo. They belong to the gymnospermae group.

Monocots belong to different families such as: gramineae, palmaceae and amaryllidaceae……etc.

 

Characteristics of monocots:

1. The vascular bundles are scattered in the transvers section of the stem.
2. The plants lack the cambium tissue for secondary grwth. The bundle is surrounded by fibrous cells known as bundle sheath.
3. The leaves have parallel venation and the leaf edge is entire with lanceolate shape.
4. They have trimerous flowers with one cotyledon in the seed.

B– Class:Dicotyledons:

The seed have two leaves (cotyledons) . They belong to the angiospermae group. Examples; faba beans, peas, cucumbers, apples, apricot, roses…..etc. which belong to different families such as fabaceae, rosaceae , convolvulaceae, cucurbitaceae , cruciferae, casuarinaceae…….etc. About 50% of these plants are are woody plants.

Characteristics of dicots:

1. Leaves have different shapes with net venation, and the edge could be entire or serrate or palmate………..etc.
2. The embryo have two cotyledons.
3. They have cambium tissue between xylem and phloem, which causes secondary growth.
4. The vascular bundles are arranged in a cylinder in the stem.
5. They have tap roots and secondary roots.
6. Flower parts are in fours or fives or multiples of them.

The Cell:

Definition: The cell is the building unit of living organisms , plants and animals .The science of studying the cell is called (cytology) . the word  cell is derived from the latin word cellula which mean small part .The cell was discovered by the british scientist Robert Hooke in 1665 A.C. in cork tissue. He noticed the cell wall only because the cork tissue is dead and all the cell contents are vanished.

There is  a very strong connection between cytology and other biological sciences such as anatomy, physiology, embryology, biochemistry, genetics and pathology. Cells are living units and all metabolic activities occur in the cells, and when they become old they die.

A lot of cell secrets were discovered early in the twentieth century when the light microscope was discovered which have a magnification power of 2000 times during the 1950s. The electron microscope were used later with a magnification power of 200000 times investigated more small bodies and organelles inside the cell.

Cell shapes range between the rod shaped, elongated, filamentous or cubic with diameters between 4 micron to 55 cm. such as ramee grass (ramie) and thecotton fibers which have 4 cm. long cells .(each cotton thread is a cell).

                            Cell components:

The cell is composed of a wall and two types of components, these are living organells and nonliving components. The protoplasm which include all the components inside the cell. Include the cytoplasm and the nucleus, which form the protoplast which contain all protoplasmic and non protoplasmic contents exclusive of the cell wall.

A-living organelles or components:

1. Cytoplasm : is the essential material containing a colloidal solution which is a gel- like with viscosity and water percentage between 85-90%. It include all the protoplasm except that in the nucleus. It contain proteins, fats sugars and mineral salts in a dissolved state. It also contain plasma membranes and vacuoles. The membranes are about 75 angstrom thick (Å) .They are selective permeable membranes. They can control the entrance of solutes and ions to the cell.

N.b. 1 Å× 10^-10 meter.

2– Nucleus: A circular or oval shaped body centrally located in the cell. It contain another smaller body known as nucleolus which contain the chromosomes representing the genetic material or genes. If the nucleus die or taken out of the cell the latter will die. The nuclear sap is thicker than the cytoplasm and more acidic, as it contain DNA deoxyribonucleic acid and ribonucleic acid RNA and messenger ribonucleic acid _mRNA which can transfer the genetic code. The nucleus diameter is 5-10 µ( micron).

3-Ribosomes: A cellular granules or particles composed of protein and RNA and functions in protein synthesis they occur in the nucleus, mitochondria and plastids. They are found free in the cytoplasm or attached to the endoplasmic reticulum.

They join the amino acids together to form chains of molecules or the protein molecule.

4- Nucleolus:  A little body in the center of the nucleus contain ribosomal RNA , its main function is the formation of ribosomes.

5. Rough endoplasmic reticulum: It consist of sacs and vesicles discovered by porter 1945. It is distributed in the cytoplasm., and a lot of ribosomes are sticked on its surface.
6. Smooth endoplasmic reticulum: It takes tubular or twisted channel shape, without ribosomes. It is anon protein producer but have other functions.
7. Golgi apparatus: in animals but in plants it is called dictyosomes, or Golgi bodies because they were discovered by the Italian scientist camello Golgi in 1898 . It is an organelle in the eukaryotes consisting of an aggregation of flat or curved and hollow membranes which function in the secretion of various compounds manufactured in the cell, or made of a group of discs called cisternae stacked on each other containing proteins and CHO. The main function is the secretion of proteins and sugars outside the cell. They secretes a mucous material to facilitate root penetration.
8. Mitochondria: Is the plural word of mitochondrion, and the single term is derived from the greek word Mitos = thread and chondrion = small granule. It is called chondriosomes well which means granule-like bodies. It is found in all respirating cells. Mitochondria is characterized by the following:

• Their length is between 1- 4 µ and 0.3-1 µ
• Is a double membrane bound cytoplasmic organelle of eukaryotic plants.
• Is the major source of power and ATP in non photosynthetic cells.
• There are a plate –like protrusions inside the mitochondrion called cristae, and it is full of fluid thicker than the cytoplasm called mitochondrion matrix.
• The matrix contain enzymes of forming fats and proteins and functioning in krebs cycle.

9-Lysosomes: A cellular organelle bounded by a single membrane, which contain acid hydrolytic enzymes capable of breaking down proteins and other complex organic molecules and even the cell itself.

10- Microtubules: They are cylindrical slender proteinaceous tubules of indefinite length, found in many types of eukaryotic cells. The single one is called tubulin.

They control the cytoskeleton of the cell and participate in the formation of the spindle during cell division, protoplasmic streaming and providing  a pathway for the entrance of solutes into the cell.

11- chloroplasts ( green plastids): A cellular organelle of photosynthetic eukaryotes that contain chlorophyll used in photosynthesis, whereby light energy is converted into chemical energy in the presence of chlorophyll .It involve the production of CHO from CO₂ and H₂O with the release of O₂. There is more than one type of chlorophyll such as chlorophyll a and b.

There are other plastids such as chromoplasts which contain yellow or orange pigments. Or leucoplasts: which are colourless plastids formed in the unexposed regions  to the sunlight of the plant such as potato tubers or turnips. They become storage bodies of starch, oil and proteins.

Thylakoid:  

Definition: A sac-like membranous structural unit of a higher plant chloroplast. Stacks of the thylakoids form the grana.

B-Ergastic substances or inclusions (non living materials):

Definition:   They are various food reserves and waste materials found in plant cells produced by metabolic processes, such as starch grains, fat droplets, crystals in the cytoplasm, vacuoles and cell walls. These are listed down:

1. Carbohydrates: means carbon + hydrogen containing water, forming sugars and starch such as glucose C₆ H12 O6 at the same ratio of H₂O with oxygen 2:1 also forming other compounds such as proteins, oils, tannins, resins, gums, rubber and alkaloids.
2. Proteins: organic compounds containing CHON +S or P it is made of amjno acids linked together by peptide bonds.
3. Oils: A biological compound consisting of three fatty acids linked to one glycerol molecule. They are fats in the solid state while they become oils in the liquid state.
4. Tannins: A heterogenous group of astringent phenol derivatives which are widely distributed in plants, used in tanning, dying and manufacture of ink, protection against decay and desiccation and an antiherbivore agent. They occur in the cell as granulated masses. They are astringent materials, which are found in quince fruit and skin of pomegranate.
5. Crystals: A type of precipitations in the plant cells made of calcium and silica salts.  Like calcium oxalates. These precipitates take different shapes such as : prismatic, star-like (druses), bipyramidal, spherical or raphides (rod-like) .The CaCO₃ crystals are called (cystolith) which means stone bag in greek.
6. Vacuols: A membrane bound region within the cytoplasm of certain plant cells. They are filled with a watery liquid. They function in maintenance of water balance within the cell, accumulation of various ions and molecules and storage of pigments ……….etc.

The term vacuome refers to a collective term for all vacuoles in a cell, tissue or plant. And the term vacuus = empty.

7. Pigments: A molecule that absorb certain wavelengths selectively, Example: chlorophyll, xanthophylls, carotene and lycopene.
8. Alkaloids: They are nitrogenous organic compounds produced by plants which have alkaline properties, and contain C,H,N which form the bases of many drugs and plant poisons. Caffeine is one of these alkaloids which have physiological effects on animals . It is present in coffee, tea and opium.

Cell Wall:

 

Definition: Is a rigid layer or layers enclosing the protoplast of a plant cell composed primarily of cellulose fibers embedded in a polysaccharide-protein matrix . The primary cell wall is thin and flexible whereas the secondary wall is stronger and more rigid and is the primary constituent of wood.

In the animal cells there is only a membrane surrounding the cell, known as plasma membrane.

   Cell Division:

 

N.b. Before studying the cell division some definitions of the main parts      of the cell and their activities should be known such as:

Mitosis:  Is the process by which new cells are generated, which involve the separation of copied chromosomes into separate cells, or a nuclear division in which chromosomes duplicate and divide to yield two daughter nuclei generally identical to the original nucleus.

Meiosis: The process by which gametes are generated for reproduction (gamete = sperm) .

Gene: Basic unit of heredity that codes for specific trait.

Locus: specific location of a gene on a chromosome (plural is loci).

Genome: The total hereditary endownment of DNA of a cell or organism. Or the total genes of an organism e.g two genomes are found in somatic cell.

Somatic cell: Include all the cells of the body which contain the complete number of chromosomes except reproductive cells. Soma or somata is the vegetative body of an organism (plant).

Chromosome: elongated cellular structure composed of DNA and protein. They are the vehicles which carry DNA in the cell. The name is derived from two latin words : chromo = coloured and soma = body.

Centromere: a region of chromosome where spindle microtubules attach during mitosis.

Chromatid: one of two duplicated chromosomes connected at the centromere.

Homologous chromosomes: a chromosome of the same size and shape which carry the same type of genes.

Haploid (1N): Cellular condition where a chromosome type is represented by only one chromosome.

Diploid (2N): cellular condition where each chromosome type is represented by two homologous chromosomes.

Centriole: A cytoplasmic organelle found in certain plant cells usually outside the nuclear envelop. It doubles prior to mitosis and the two centrioles move to opposite poles to organize the spindle apparatus.

 

 

 

                                 Stages of cell division:

 

The cell passes through four to five stages to complete the division process to form two daughter cells, these are:

1. Interphase: The period between two active mitotic or meiotic divisions or the resting period in the cell cycle without divisions. The cellular METABOLIC ACTIVITIES are high . The cell size increase , and this stage accounts for 90% of the time of  the cell cycle.
2. Prophase: The following events take place during this stage:

• The chromosomes condense and become visible.
• Centrioles form and move toward opposite ends of the cell (the poles).
• The nuclear membrane dissolves.
• The mitotic spindles form.
• Attachment of spindle fibers to each sister chromatid at the kinetochore (centromere).

3. Metaphase:

• The centrioles complete their migration to the poles.
• The chromosomes line up in the middle of the cell (the equator.

4- Anaphase:

• Spindles attached to kinetochores begin to shorten.
• This exerts a force on the sister chromatids that pulls them apart.
• Spindle fibers continue to shorten pulling chromatids to opposite poles.
• This ensures that each daughter cell gets identical sets of chromosomes.

5- Telophase:

• The chromosomes decondense.
• The nuclear envelop form.
• Cytokinesis reaches completion creating two daughter cells. cytokinesis means cytoplasmic division and formation of cell wall).

                           Mycorrhizza:

    It is a symbiotic association between fungi and roots of many types of plants. The plural is mycorrhizae. The term is derived from two words : mycology= fungi science and rrhiza = radicle or root. Symbiosis may be mutualistic or somewhat parasitic. Fungi may be superficial (ectotrophic) or called:

Ectomycorrhiza: In which the fungus surrounds the root tip with a dense sheath and penetrate into the intercellular spaces of the host. Such roots are short branched and appear swollen, or contained within the host cells and those are called:

Endomycorrhiza or Endotrophic: In which the fungus is not the conspicuous on the root tip . It develops intracellular hyphal infections in the host root cortex. Such roots are not markedly affected in form but are darker in color.

Ericoid mycorrhiza: The term is derived from the family Ericaceae العائلة الخلنجية which include some plants such as bear berry.and arbutus قطلب .This type of mycorrhiza consist of dense coils of hyphae in the outermost layer of the root cells. These hyphae donot extend very far into the surrounding soil. The ericoid can decompose m

aterials which means they have saprophytic capabilities.

The partnership between the fungus and plants is known since at least the mid 19^th. Century and described by Francizek kamieriski in 1879—1882 and more research was carried out by Albert Bernhard Frank who introduced the term mycorrhiza in 1885.

 

• Benefits of Mycorrhiza:

 

1. They promote the growth of plants if the soil or roots are inoculated with the fungus , for example: pine seedlings grow very slowly in sterilized soil.

Note: orchids never grow free of mycorrhiza.

2-They digest organic matter in soils and make N sugars and minerals available to the roots.

3. They increase the absorbing surface of water and minerals for the host plant by studying the radioactive isotopes of Ca , P and K. It is been found that these minerals are absorbed in greater amounts by plants with mycorrhizae than by plants without them. They participate in N fixation in the roots.
4. The fungi enables the plant to grow under unfavorable soil conditions. On the other hand they obtain growth promoting substances and food from the host plant.
5. The roots infected or inoculated with mycorrhiza become short and thick, because they lack root caps and root hairs and they are not able to branch.

                                        LICHENS:

Definition: A composite structure consisting of a fungus and algae   interwoven together to form one thallus. The fungi are either ascomycetes or basidiomycetes and the participating fungus is called mycobiont, from the greek word (Mykes = fungus and bios = life). While the alga is called phycobiont from the greek as well (phycos = alga and bios = life).

The two organisms form a symbiotic life , that the fungus obtain his food from the alga and supply the alga with water and minerals and protect the alga from drying and unfavorable conditions. The major part of the lichen is fungus. There are about 15000 species of lichens

There are three types of lichens these are:

1. 1. crustose: It is a crust –like which form a thin flat crust strongly attached to the surface of growth.
2. 2. Foliose: It is a leaf like or flattened Lichen as in the erect blade-like thallus of certain algae. It is loosely attached to the substrate or surface.
3. Fruticose: It is a shrub-like or becoming woody also called frutescent.

THALLUS:

Is a single plant body devoid of differentiated root , stem or leaf, e.g. algae and fungi. Thallus is single while the plural is Thalli.

Lichens live in arctic tundra, hot deserts rocky coasts and toxic slag heaps الخبث أو الجفاء  and as epiphytes نبات هوائي on leaves and branches in rain forests and temperate wood lands.

Some Lichens are:

1. Leprose = powdery on leaves of plants.
2. Squamulose = Scale-like structures.
3. Gelatinous lichens.

Reproduction or propagation of Lichens: There are three ways of lichen propagation:

1. By pieces which is a breakup of the lichens body and grow.
2. Spores from the fungus may grow, but if they donot meet the suitable algae to live with, they will die.
3. By Soredia: which is an a sexual reproductive structure consisting of few algal cells surrounded by fungal hyphae , when separated they form a new lichen.

                 Characteristics Of Lichens:

 

1. Their exact taxonomical position in the plant kingdom is not clear. But they are usually placed with the fungi , because the greater proportion of the plant body consist of fungal part.
2. They send short hyphal branches called haustoria to penetrate the algal cells.
3. Reproduction is by soredia.
4. The fungus alone cannot survive without algae , while the algae can survive and live without fungus under favorable conditions.
5. The penetrating rhizoids in the substratum and the organic acids produced during the metabolic activities of the fungus promote the dissolving of the essential minerals.
6. Lichens growing on the surfaces of bare rocks might cause a gradual erosion of these rocks, as a result of mechanical and chemical effects.

The debris blown by wind accumulates on the rough surfaces and this support the growth of other lichens. This succession participate in converting barren areas into fertile areas.

7. Some lichens form sources of food for animal grazing in the arctic regions such as reindeer moss طحالب غزال الرنة .
8. Some lichens are used in the perfume industry and dying processes عمليات الصباغة and sources of litmus indicator as the purple color of litmus is changed to red by using acids and changing to blue by using alkaline materials. Some are used in dying of clothes.
9. Some lichens were used in ancient Egyptian mummies.
10. Some lichens are used as pollution indicators.
11. lichens are used for treatment of high mountain dwellers and arctic survivors.

                                   AZOTOBACTER:

 

Scientific name: Azotobacter croococcum

Discovered by the deutch microbiologist and botanist Martinus Beijerinck in 1901. They are found in neutral and alkaline soils, in water and associated with some plants.

Definition:  Azotobacter is an aerobic gram negative species gm-_ve . They are about six species. They are spherical or oval in shape. They are motile and they form thick walled cyst. Free living in soil, and able to fix Nitrogen when they penetrate the  plant roots to the cortex. While the rhizobium bacteria cannot fix  N.

Is used by man for the production of biofertilizers. They live symbiotically with the plants especially the legumes as the plant supply all the necessary nutrients and energy for the bacteria. After a week of infection they make nodules or after 2-3 weeks after planting in the field depending on the:

1. Legume species. Examples: chickpeas, Lentils, faba beans and Peas.
2. Germination conditions

                        Characteristics of Azotobacter:

 

1. They are spherical, oval or rod shaped about 1-2 micrometers µm in diameter arranged in chains or clusters.
2. Cysts are resistant to bad conditions such as UV light (ultraviolet light) and drying. They can stay for 24 years and then resume growth under favorable conditions such as pH^7.5 , source of carbon and 20-30 C˚ temperature.
3. They need molebdenium or vanadium ions to fix nitrogen.
4. They produce dark brown pigment called melanin or yellow green to purple .
5. They have a full range of enzymes needed to perform the N fixation such as ferridoxin and hydrogenase and nitrogenase .

6.Used as a biological fertilizer in the form of azotobacterin and production of alginic acid (E400) which is used as antiacid in medicine and added to ice cream as a food additive.

Biological N fixation is the process that change inert N₂ to biologically useful ammonia gas NH₃. This process is only mediated by bacteria.

8. When the N fixing bacteria die they release N to the environment.
9. When nodules are young and not yet fixing N they are white or gray inside . As they grow in size they gradually turn pink or reddish indicating that N fixation has started . This color is caused by leg haemoglobin similar to that in the blood, which controls the O₂ flow to the bacteria.
10. Young nodules on perennial legumes such as alfalfa and clover are finger-like in shape , and they become palm-like when the mature and they are about one cm. or less in diameter.
11. In annual legumes the nodules are round in shape as the size of a large pea .They are short lived and may be replaced constantly during the growing season.
12. When the legumes start to fill the pods , nodules will lose their ability to fix N. Because the plant feeds the developing seeds rather than the nodule.
13. When the nodules become inactive they turn green and will be discarded.

N.B. Bean plants: have less than 100 nodules/plant.

Soy bean plants: have several hundred nodules/plant.

Peanuts: have 1000 nodules/plant.

 

 – s slime mould

euglena

  rhodophyta

 

 

 

mushrooms

mushrooms Lichens

 

 

 

 

mycorrhiza

 

 

 

 

Phaeophyta

 

chlorophyta

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Azotobacte

Crustose lichen