Cytology and Genetic Course PDF

Cytology and genetic course Lectures: 1 and 2 What is cytology and some terms related to it. Cytology is also known as cell biology. It is the study of cell. It is important for the researchers or biologists in generating vaccines, medicines etc. The cell is the basic unit of life (a unit of protop...

Cytology and genetic course Lectures: 1 and 2 What is cytology and some terms related to it. Cytology is also known as cell biology. It is the study of cell. It is important for the researchers or biologists in generating vaccines, medicines etc. The cell is the basic unit of life (a unit of protoplasm). Plant cells (unlike animal cells) are surrounded by a thick, rigid cell wall and plastids in the case of eukaryotic cells. Prokaryotic cells have not organelles and membrane surrounding nuclear material of the cell, such as bacteria. Plants are unique amongst the eukaryotes organisms whose cells have membrane- enclosed nuclei and organelles, because they can manufacture their own food (autotrophic).  Historical review The cytology is consider a young biological science and has taken its individual entity by the end of 19 centaury. Its gradual development in the last centuries as follows: Before 19 th century 1- Aristotle and Paracelsus: concluded that all animals and plants are constituted by few elements which are repeated in one of them. They were referring to macroscopic structure of an organism such as roots, leaves, and flowers common to different plants , organs in animals. Devinci in 1485: use lenses in viewing small objects Jan Swammerdam 1658:gave first description of the cell(blood cells).  Marable (1808) reported that plants consists of membranous cellular tissues Turpin (1826):reported the occurrence of cell division. R. Brown (1826 and 1831) reported Brownian movement in cellular particles and described the nucleus as a central feature in plant cells. Felix Dujardin (1835) Described Protoplasm in protozoa M. Schleidenn 1838):described the nucleoli and proposed cell theory, stated all plant s composed of cells along with T. schwann 1939 for cell theory to animals. Rudolf virchon (1858) stated all cells come from preexisting cells.  Robert Hooke (1665-1703) he examined a thin slice of cork , he observed its hony –combed or porous structure. He found similar alveoli in other plant tissue and gave them the name “ cells” ( L., cellula – little room). Leeuwenhock (1632- 1723): discovered the protozoa, red blood cells , muscles , nerves skin. Fontana 1781: described the nucleolus from the skin The 19th century can be considered as the “classical era of cytology because most important cytological investigations were made extensively tin this century.  Purkinge 1840: named the cell contents as protoplasm. Haecked 1866: named plastids Strasburger 1875: described chromosomes Principles of cell theory 1- all livening thing are made of cells 2- Smallest living unit of structure of all organisms is the cell 3- all cells arise from preexisting cells 4- most are microscopic  Cells surface area 2 cm  Comparison of cells and Viruses Viruses Viruses belong to the twilight zone between the living and non-living worlds. They infect almost every kind of prokaryotic and eukaryotic cells and are obligate cellular parasites. They are metabolically inert , however, they are active within host. They are crystalized like molecules Viruses are much simpler than cells and very different in both structure and life cycle Their size ranged from 10 nm to several hundred nm. The largest viruses are at least as smallest bacteria mycoplasma, chlamdiae and rickettsia).  Classification of cells of cellular organisms The body of all livening organisms except viruses and certain plants such as rhizopus , vaucheria has cellular organization and may contain one or many cells. The organisms with only one in their body are called unicellular organisms The organisms having cells in their body are called multicellular organisms. Prokaryotic cells ( Gr., Pro- primitive; Karyon –nucleus ) Examples: bacteria, blue green algae, etc.,) 1- PPLO(Pleuropneumonia- like organisms) 2-they are bacteria- like organisms  They are lacking cell wall and mesosomes They are placed in the group Mycoplasmataceae of bacteria (Schizomycetes) Their diameters range from 0.1 – 0.3 um They have DNA , DNA is not enveloped by any nuclear membrane. Chlamydia and Rickettsia They are a small bacteria. They are parasites of cells in vertebrates They have both DNA and RNA as other bacteria. The cell membrane surrounded by a cell wall. They reproduce like true bacteria by cell division.  Bacteria They are microscopic , unicellular, achlorophyllous (but have chromatophores) and asexually reproducing prokaryotes. Either saprophytic or parasitic made of existence Size : an average: the bacterial cells 1.25 µm. The smallest (0.15- 0,30 µm in length) The largest (13-15 µm in length) Form: Coccus, Bacillus and Spirillum  Identification Cytology is derived from Greek word kytos means ‘hollow vessel’ or ‘container’. The prefix cyto means ‘cell’ and suffix ology means ‘study of’. Therefore we can say that cytology is the study of cell. It is that branch of science which deals with the structural and functional organization of cell. It is also known as cell biology. This article deals with the cytology, its importance and some terms related to it. Source: http://docs.neu.edu.tr/staff/deniz.balci/  Terms related to Cytology 1. Karyokinesis: Division of nucleus during cell division. 2. Cytokinesis: Division of cytoplasm. 3. Diploid: Two complete set of chromosome is known as diploid which is found in somatic cell. 4. Haploid: Single set of chromosome in cell is called haploid which is found in gametes.  5. Crossing over: Exchange of genetic material between two non sister chromatids takes place during meiosis cell division. 6. Homologous chromosome: A pair of chromosome having same size and shape bearing corresponding gene. 7. Phenotype: The character of organism which can be seen directly. 8. Genotype: Genetic constitution of organism. 9. Tonoplast: The membrane surrounding the vacuole. 10. Unit membrane: The basic trilamilar structure of cell membrane.  Differences between plant and animal cells Features Plants animals cell wall present absent vacuoles present absent chloroplasts present absent centrosomes and centrioles absent present Some differences between Eukaryotic and Prokaryotic Cells feature differences Eukaryotic Prokaryotic Cell Cell Nucleus Present Absent Number of chromosomes More than one One--but not true chromosome: Plasmids Membrane bound Nucleus Present Absent Lysosomes and peroxisomes Present Absent Sources: https://www.diffen.com/difference/Eukaryotic_Cell_vs_Prokaryotic_Cell https://www.biologyonline.com/tutorials/plant-cells-vs-animal-cells  Mitochondria Present Absent Ribosomes larger smaller Vesicles Present Present Golgi apparatus Present Absent Chloroplasts Present (in plants) Absent; chlorophyll scattered in the cytoplasm Vacuoles Present Present Cell size 10-100um 1-10um  Plant cell https://www.sciencefacts.net/wp-content/uploads/2020/01/Plant-Cell-Diagram.jpg