Introduction to cell
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The document discusses the structure and function of prokaryotic cells. Prokaryotic cells are much smaller and simpler than eukaryotic cells, lacking organelles like the nucleus and mitochondria. The basic structure of a prokaryotic cell includes an outer cell wall and cytoplasmic membrane, cytoplasm containing ribosomes and other inclusions, and sometimes additional structures like flagella, pili, or plasmids. The cell wall provides shape and rigidity while the membrane is semipermeable and controls movement of molecules in and out. Ribosomes perform protein synthesis and mesosomes are involved in respiration.
Introduction to cell
- 1. Introduction: Cells • Cell – basic unit of life • Based on the organization of their cellular structures, all living cells can be divided into two groups: eukaryotic and prokaryotic • eukaryotic cell types - Animals, plants, fungi, protozoans, and algae • prokaryotic cell types - bacteria
- 2. Prokaryotic Cells • much smaller (microns) and more simple than eukaryotes • prokaryotes are molecules surrounded by a membrane and cell wall. • they lack a true nucleus and don’t have membrane bound organelles like mitochondria, etc. • large surface-to-volume ratio : nutrients can easily and rapidly reach any part of the cells interior
- 3. Structure of A Prokaryotic Cell Dr Ekta Chourasia
- 4. Structure of A Prokaryotic Cell • Outer layer – two components: 1. Rigid cell wall 2. Cytoplasmic (Cell/ Plasma) membrane – present beneath cell wall • Cytoplasm – cytoplasmic inclusions, ribosomes, mesosomes and nucleus • Additional structures – plasmid, slime layer, capsule, flagella, fimbriae (pili)
- 5. Function of Cell Components • Cell wall 1. Shape, rigidity 2. 10-25 nm thick 3. Composed of peptidoglycan/ mucopeptide (N acetyl glucosamine & N acetyl muramic acid) • Cytoplasmic membrane – semipermeable membrane: controls the inflow and outflow of metabolites
- 6. Function of Cell Components • Ribosomes – protein synthesis • Mesosomes – 1. Multilaminated structures formed as invaginations of plasma membrane 2. Principal sites of respiratory enzymes 3. Coordinate nuclear & cytoplasmic division during binary fission • Intracytoplasmic inclusions – reserve of energy & phosphate for cell metabolism
- 7. Additional Organelles 1. Plasmid – • Extranuclear genetic elements consisting of DNA • Transmitted to daughter cells during binary fission • May be transferred from one bacterium to another • Not essential for life of the cell • Confer certain properties e.g. drug resistance
- 8. Additional Organelles 2. Slime layer & capsule – • Viscous layer secreted around the cell wall. • Protects bacteria from lytic enzymes • Inhibits phagocytosis 3. Flagella – organs of locomotion 4. Fimbriae/ Pili – 10-20µ long, organs of adhesion
- 9. The Cell, Structure & Function The structure of a Prokaryotic cell ? Protects the cell and maintains its shape Cell Wall Thick cell wall with little lipid: Gram positive Thin cell wall with 2 layers: Gram negative Capsule Some bacteria have a slimy layer of Polysaccharides for protection. 70s protein synthesis Ribosomes Flagellum motility Nuclear Genetic material : DNA Material Plasmid rings of genetic material for antibiotic Resistance Mesosome For Respiration