Cell Structure And Functions PDF

CELL STRUCTURE AND FUNCTIONS Cell as basic unit of life The study of cells Prokaryotes and Eukaryotes The cell and organelles Transport across plasma membrane  * PROKARYOTES AND EUKARYOTES I. Prokaryotes (Prokaryotic cells) single-celled (unicellular) smallest and simplest cells (1 t...

CELL STRUCTURE AND FUNCTIONS Cell as basic unit of life The study of cells Prokaryotes and Eukaryotes The cell and organelles Transport across plasma membrane  * PROKARYOTES AND EUKARYOTES I. Prokaryotes (Prokaryotic cells) single-celled (unicellular) smallest and simplest cells (1 to 10 µm) Bacteria and Archaebacteria. cytoplasm/protoplasm enclosed by plasma membrane. no cytoskeleton (filamentous network of protein) cell wall made of peptidoglycan – maintain cell shape. ⮚Gram negative bacteria - thinner cell wall, does not retain the Gram stain ⮚Gram positive bacteria – thicker cell wall, retain the Gram stain (purple)  * PROKARYOTES AND EUKARYOTES I. Prokaryotes some have capsule – limit phagocytosis no membranous organelles mesosomes – infolding of plasma membrane (site of cellular respiration) have ribosomes to synthesise protein Some have flagella  * PROKARYOTES AND EUKARYOTES I. Prokaryotes Genetic material - ‘naked’ circular DNA (nucleoid) Some have plasmid (small circular DNA) – store important genes e.g. resistance to antibiotics  * PROKARYOTES AND EUKARYOTES I. Prokaryotes high metabolic and growth rate, and short life time some has flagella for movement in liquid environment pili (pilus – singular) - attach to surfaces. growth and reproduction by binary fission  * PROKARYOTES AND EUKARYOTES II. Eukaryotes (Eukaryotic cells) animal and plant cells (main groups) Unicellular or multicellular Larger size (10 to100 µm) bounded by plasma membrane * PROKARYOTES AND EUKARYOTES II. Eukaryotes (Eukaryotic cells) have distinct nucleus that are enclosed by nuclear envelope contain membrane-bound organelles (membranous organelles) contain cytoskeleton (supporting matrix of protein) flagella are more complex Undergo meiosis and mitosis  * PROKARYOTES AND EUKARYOTES  The differences between prokaryotic and eukaryotic cells  * THE CELL AND ORGANELLES Exterior structure:- ⮚Cell wall (plants and bacteria) ⮚Plasma membrane ⮚Cilia and flagella Interior structure:- ⮚Cytoplasm ⮚Cytoskeleton (in eukaryotes) ⮚Organelles (in eukaryotes) – 3 groups:- ▪ Endomembrane system ▪ Mitochondria and chloroplast ▪ Ribosomes and nucleus  Eukaryotic cell (animal cell)  * THE CELL AND ORGANELLES Exterior structure of cell - Cell wall enclose the plasma membrane of plants, bacteria, fungi, algae, and some archae (not in animals and protozoa) made of cellulose (plant), peptidoglycan (bacteria) tough, usually flexible but sometimes rigid function - protection and support against mechanical stress  * THE CELL AND ORGANELLES Exterior structure of cell – Plasma membrane enclose the cytoplasm/protoplasm two layers of phospholipid (bilayer) with embedded proteins semi-permeable (selectively permeable)  * THE CELL AND ORGANELLES Exterior structure of cell – Plasma membrane Functions separating the interior from the environment provide shape as cell adhesion ion channel conductance cell signaling (cell interact with their environment and other cells around them) attachment point for the cytoskeleton  * THE CELL AND ORGANELLES Exterior structure of cell – Cilia (cilium – singular) projections from the cell - motile and non-motile (primary) primary cilia are found on nearly every cell in human body functions - movement - sweep substances across cell surface - Sensory receptors / mechanoreceptors  * THE CELL AND ORGANELLES Exterior structure of cell – Cilia (cilium – singular) same structure and diameter (0.25µm), short (2- 20µm), numerous (number) made up of microtubules covered by plasma membrane microtubules - hollow cylinders made up of repeating protein structures  * THE CELL AND ORGANELLES Exterior structure of cell – Cilia (cilium – singular) Microtubules are arranged in a ring: - Primary cilia - nine triplets (9+0) - Motile cilia - nine pairs surround two central microtubules (9+2) Basal body - anchor cilium to the cell (basal body = centriole)  * THE CELL AND ORGANELLES Exterior structure of cell – Flagella (flagellum) projections from the cell structure - long (10-200µm), few (number) made up of microtubules covered by plasma membrane arranged in a ring:- nine pairs surround two central microtubules (9+2) basal body anchor flagellum to the cell function - movement  * THE CELL AND ORGANELLES Exterior structure:- ⮚Cell wall (plants and bacteria) ⮚Plasma membrane ⮚Cilia and flagella Interior structure:- ⮚Cytoplasm ⮚Cytoskeleton (in eukaryotes) ⮚Organelles (in eukaryotes) – 3 groups:- ▪ Endomembrane system ▪ Mitochondria and chloroplast ▪ Ribosomes and nucleus Thank you