Cytology Lab 3 PDF

CYTOLOGY LAB.3 Prepared By : Rehab Nady Beni–Suef University. Faculty of Science. Zoology Department. Practical histology Third lab Prokaryotes and Eukaryotes Presented By:...

CYTOLOGY LAB.3 Prepared By : Rehab Nady Beni–Suef University. Faculty of Science. Zoology Department. Practical histology Third lab Prokaryotes and Eukaryotes Presented By: Eman Refaat  Prokaryotes and Eukaryotes 01 02 prokaryotes Eukaryotes -(pro- = “before”; -((eu- = “true”) -(kary- = “nucleus”). -(kary- = “nucleus”). -Only the single-celled ex: Cells of animals, plants, organisms of the domains fungi, and protists ex: Bacteria and Archaea are classified as prokaryotes  prokaryotic and eukaryotic cells * All cells share four common components: 1) Plasma membrane, an outer covering that separates the cell’s interior from its surrounding environment. 2) Cytoplasm, consisting of a jelly-like cytosol in which other cellular components are found. 3) DNA, the genetic material of the cell. 4) Ribosomes, which synthesize proteins. However, prokaryotes differ from eukaryotic cells in several ways. 1) Prokaryote 2- Eukaryotic cell cell :  -Has not nucleus -Has a nucleus -DNA scattered in the cytoplasm -DNA inside the nucleus -Not Surrounded by nuclear -Surrounded by nuclear membrane membrane -Presented in nuclear area Mitosis and meiosis division meiosis division Respiration in prokaryotes Respiration in eukaryotes Through plasma membrane Through mitochondria 1- Prokaryotic cell This figure shows the generalized structure of a prokaryotic cell. All prokaryotes have chromosomal DNA localized in a nucleoid, ribosomes, a cell membrane, and a cell wall.  Cell Wall: It is the outermost layer of the cell which gives shape to the cell. It is a peptidoglycan cell wall which help in protection and prevents dehydration. Capsule: It is an polysaccharide capsule the outer protective covering layer found in the bacterial cells, in addition to the cell wall. It protects the cell when engulfed, and helps in the attachment of cells to nutrients and surfaces. Cell Membrane: This layer surrounds the cytoplasm and regulates the entry and exit of substances in the cells. Pili: These are hair-like outgrowths that attach to the surface of other bacterial cells.( help in reproduction ) Flagella: These are long structures in the form of a whip, that help in the locomotion of a cell.  Fimbriae : hair-like structures help in attachment to a host cell. Ribosomes: These are involved in protein synthesis they are small ribosome Plasmids: non-chromosomal DNA structures. These are not involved in reproduction. Nucleoid Region: It is the region in the cytoplasm where the genetic material ( chromosomal DNA )is present. Reproduction in Prokaryotes: Asexually by binary fission or transfer genes by conjugation, Transformation and Transduction. Cell Size - At 0.1 to 5 μm in diameter, prokaryotic cells are smaller than eukaryotic cells, which have diameters ranging from 10 to 100 μm. The small size of prokaryotes allows quick diffusion of ions and organic molecules that come into or out of them. - Most prokaryotes have a peptidoglycan cell wall. acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. Many have a polysaccharide capsule. enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella for locomotion. Pili to exchange genetic material during conjugation. Fimbriae to attach to a host cell. 2- Eukaryotic cell This figure show the major organelles and other cell components of a typical animal cell.  Plasma Membrane: The plasma membrane separates the cell from the outside environment. It comprises specific embedded proteins, which help in the exchange of substances in and out of the cell. Cell Wall : A cell wall is a rigid structure present outside the plant cell and absent in animal cells. It provides shape to the cell and helps in cell-to-cell interaction, It is composed of cellulose, hemicellulose, pectins. Golgi Apparatus: flat disc-shaped structures called cisternae , They are arranged near the nucleus. It is an important site for the formation of glycoproteins and glycolipids. Ribosomes: These are the main site for protein synthesis and are composed of proteins and ribonucleic acids in large and small subunit  Cytoskeleton :The cytoskeleton is present inside the cytoplasm, which consists of microfilaments, microtubules, and fibres to provide perfect shape to the cell and stimulate the cell movement. Endoplasmic Reticulum: It is a network of small, tubular structures that serve many roles in cells as calcium storage , protein synthesis and lipid metabolism Endoplasmic Reticulum is of two types: Rough Endoplasmic Reticulum contains ribosomes. Smooth Endoplasmic Reticulum that lacks ribosomes. Mitochondria: “powerhouse of cells” because they produce energy. Lysosomes: they possess hydrolytic enzymes to digest protein, lipids, carbohydrates, and nucleic acids.  Membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Glycoprotein Extracellular fluid Glycolipid Phospholipids Cholesterol Transmembrane proteins Peripheral protein Cytoplasm Filaments of cytoskeleton AP Biology  An electron micrograph of a plasma membrane of a human red blood cell seen in cross section. AP Biology AP Biology AP Biology AP Biology  Any Questions?? AP Biology