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Divisions of Basic Sciences. Mathematics. Physics Chemistry Biology ( Zoology – Entomology – Biotechnology - Botany – Microbiology .....etc) Geology Computer Statistics. ZOOLOGY.
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Divisions of Basic Sciences Mathematics. Physics Chemistry Biology (Zoology – Entomology –Biotechnology - Botany – Microbiology .....etc) Geology Computer Statistics
ZOOLOGY • It is the science that dealing with the study of structure and function of animals as well as the relationship of the animals with the surrounding environment. • Main divisions of Zoology • Cytology- Histology- Embryology- Anatomy- Systematic Zoology- Physiology- Immunology- Invertebrates- Chordata- Histochemistry- Molecular Biology- Genetics- Fish Biology- Marine Biology- Ecology- Animal behavior- Paleontology and others ……….
What is Cytology • Cytology is the study of different types of cells and the activity and function of their internal organization. • Some Types of Microscopes:- 1- Light M. (LM) 2- Phase contrast M. 3- Ultraviolet M. 4- Electron M. (Transmission EM & Scanning EM)
Cell theory Some of the Scientists that help in the discover of the cell • Leuwenhoek & Robert Hooke (1665): the 1st one discovered the cell • Robert Brown 1838: discovered the nucleus. • Schwann 1839 and Schleiden (1933): gave the formulation of cell theory • Purkinje 1840: describe the protoplasm and Altman 1840 discovered the mitochondria. • Golgi 1898: described net-like structure in the cytoplasm (Golgi apparatus).
Cell theory • “Cells are organisms and animals as well as plants are aggregates of these organisms arranged in accordance with definite laws.” • The cell is a mass of protoplasm enclosed in a membrane and contain one or more nuclei. • The cell is the unite of structure and function of all living organisms.
Shape, Size and Number of cells • Shape: spherical, polygonal or polyhedral, flat, pyramidal, columnar, spindle, and amoeboid. • Size: from 200 -15000 microns (microbes to egg cells). Egg diameter of ostrich may reach 30cm. Nerve cell may reach 90 cm long. • Number: One cell in unicellular animals (Protozoa). billions of cells in adult Human. • Constitution: 1- Cytoplasm. 2- Nucleus. The two are called PROTOPLASM (Living matter).
Cytoplasm • It is Semitransparent, viscous and jelly-like substance. • Emulsion: it is a colloidal system composed of solid and liquid materials. • Chemical composition: 80% water, 12% proteins, 5% fats, 2% DNA & RNA, 1% steroids and others. • Structure: 1- Living structures called organelles. 2- Non-living structures called deutoplasm or metaplasmic inclusions. • It includes 1-Temporary products (secretory & excretory). 2- Storage materials (glycogen, fats droplets, amino acids ….others) and 3- Structural substances as pigments of hair and eyes.
Cell organoids (Organelles) 1- Plasma membrane: • Daneilli (1954) suggested the Trilaminar (three-layered) structure (Lipoprotein). • There are minute pores through the PM. • Selective permeability of PM. • Function of PM: a) Provide mechanical support and structural integrity of the cell. b) Control the flow of substances in and out of the cell. c) Mechanisms that regulate diffusion of substances: 1- Simple Diffusion. 2- Carrier-mediated transport. 3- Phagocytosis. 4- Pinocytosis.
2- Mitochondrion • Shape: granules, rods or threads. • Occurrence: in all types of the living cells except mature R. B. Cs. • Location: concentrated at the parts with high rate of metabolism as cells of the kidney. • Number: It is constant for every kind of cells. It is markedly high in the active cells (liver & kidney). • Chemical nature: Proteins, Phospholipids and nucleic acids. • Ultra structure: They are sac-like structures bounded by 2 membranes of lipoid nature. The outer membrane is smooth and elastic, while the inner one is folded giving a large number of Ridges called Cristae. • Internal chamber contain an aqueous matrix and Crestae have various oxidative enzymes.
Functions of Mitochondria 1- Provide cell with energy (Power house or Batteries of enzymes). 2- Store energy in ATP to be latter utilized by the cell. 3- Responsible for the formation of tail sheath of sperms.
3- Golgi complex It is also named Dictyosome, Lipochondria or Golgi apparatus • 1st described in liver cells then in a large number of animal cells. • Occurrence: Found in all living cells except germ cells and R.B.Cs. • Shape: Network of curved elements. • Location: in the area of smooth ER. At the excretory pole of the exocrine secretory cells. In mature nerve cells, it is perinuclear position. • Ultra structure: a system of parallel saucer-shaped channels (4-8) as well as collection of vesicles and vacuoles. • Chemical nature: Lipoproteins.
Function of Golgi apparatus 1- Storage and ensheathing of secretory products of the cells. 2- Help in keeping water concentration in the cells and synovial fluid. 3- Help in the formation of acrosome of sperms. 4- Take part in the secretion of fats, elaboration of Nissl bodies and metabolism of carbohydrates. 5- May be used in transport and distribution of materials within the cells.
Endoplasmic Reticulum ER Other name: Ergastroplasm Occurrence: in all nucleated cells Structure: network of parallel membrane-like ,flattened and vesicular spaces called cisterna. Location: between the nucleus and plasma membrane. Present in young nucleated R. B. Cs. And absent in mature ones because they lost their nuclei. Chemical nature: Lipoproteins Kinds of ER: 1- Granular (Rough) ER: covered by ribosome and it is found at the basal region of secretory cells. 2- Agranular (Smooth) ER: devoid of ribosome and is found in retina (pigment cells) of the eye and striated muscles.
Functions of ER 1- GER or RER is essential for protein synthesis. 2- SER may be conduct the nerve impulses. 3- ER helps in transportation of substances between the nucleus and plasma membrane as well as between the interior and exterior of the cell. 4- ER serves in storing the synthesized molecules. 5- ER take part in the synthesis of steroids.
Centrosome • Occurrence: in the majority of animal cells except mature nerve cell, mature R.B.Cs. and cells of higher plants. • Shape: consists of 1 or 2 deeply stained bodies known as centrioles or diplosomes. • Location: close to the nucleus. • Ultrastructure: each centriole is a hollow cylindrical structure. Its wall composed of nine tubular triplets embedded in a dense amorphous matrix. The two centrioles lie perpendicular to one another. The pattern of centriole is 9 +2.
Function of Centrosome 1- play an important role in cell division. 2- it has some relationship with Locomotion in ciliated and flagellated organisms. 3- it may be involved in the formation of tails of sperms.
Lysosomes • 1st discovered in liver cells, then in many other animal cells. It is called suicide bags(حقائب الأنفجار) • Shape: small spherical vesicles surrounded by 2 membranes. Their cavities contain many hydrolytic enzymes. The outer membrane is impermeable to the diffusion of enzymes. • These enzymes are initially formed in the ribosomes of GER then directed to Golgi complex where they are ensheathed by membranes. • Autolysis (self digestion): it is the rupture of the membrane of lysosomes dissolving the cell contents. This rupture occurs quickly in dead cells.
Function of Lysosomes 1- Play an important role in the digestion process inside the cell (intracellular digestion). 2- Take some part in carbohydrate metabolism. 3- Involved in the process of destruction of some tissue or cell contents as tail degeneration of tadpole of Amphibia during Metamorphosis.
Nucleus • Occurrence: existing in nearly all cells and is the controlling centre of the cell. It is essential for the life of the cell. • Interphase nucleus: it is the phase of nucleus between two successive division. • Shape: rod-shape in cylindrical columnar cells, flattened in squamous cells, spherical in polyhedral, cubical or spherical cells, irregular are rarely found as bilobed, multilobed and kidney shaped are found in W. B. Cs. • Size: related to that of the cytoplasm. • Karyocytoplasmic ratio: it is the relation between the size of the nucleus and the cytoplasm. • Number: most cells contain one nucleus (mononucleated). Some cells are binucleated as liver cells. Multinucleated cells contain more than two nuclei as osteoclast and striated or skeletal muscle fibers (synciytium).
Ultrastructure of Nucleus 1- Nuclear envelope (Karyotheca): it is double layered membrane (There is outer and inner membranes). It similar to PM in chemical structure (lipoproteins). It is provided with minute pores. The outer membrane is continuous with the RER. It has a selective permeability. It control the flow of materials in & out of the nucleus. • Barr body: It is a small, oval, darkly-stained particle of chromatin (Barr, 1949). 1st described in nerve cells of female cat, then observed in many Interphase nuclei of female animals. It is used for distinguishing of males from females. 2- Nuclear sap (matrix or Karyolymph)): it is a colorless gel-like fluid. It is acidophilic filling the meshes of chromatin network.
Nucleolus 3- Nucleolus: Found in all animal cells. There is one or two nucleoli. It is composed of RNA+ protein. It is deeply stained with basic dyes. It is formed by the nucleolar organizer. • Function of nucleolus: a- Protein synthesis. b- pass the genetic material & information from nucleus to cytoplasm to initiate cell division. c- play some role in the synthesis and storage of RNA. 4- Chromatin: it is in the form of fine lightly stained network in interphase nucleus. In addition, some coarse granules of darkly-stained chromatin called chromo-centers. During cell division this network is fragmented into long and thin threads called chromatin threads (chromosomes).
