The Cell (Allied) PDF

The Cell BY DR ZAYYANU USMAN DEPT OF ANATOMY,FBMS,CHS,UDUS Wenesday,12/02/2020.  Outline Introduction Historical backgrounds Cell types Cell organelles Summary/Conclusion Q &A  Cells Smallest living unit Most are...

The Cell BY DR ZAYYANU USMAN DEPT OF ANATOMY,FBMS,CHS,UDUS Wenesday,12/02/2020.  Outline Introduction Historical backgrounds Cell types Cell organelles Summary/Conclusion Q &A  Cells Smallest living unit Most are microscopic Discovery of Cells Robert Hooke (mid- 1600s) – Observed sliver of cork – Saw “row of empty boxes” – Coined the term cell  Cell theory (1839)Theodor Schwann & Matthias Schleiden “ all living things are made of cells” (50 yrs. later) Rudolf Virchow “all cells come from cells” Principles of Cell Theory All living things are made of cells Smallest living unit of structure and function of all organisms is the cell All cells arise from preexisting cells (this principle discarded the idea of spontaneous generation) Cell Size Cells Have Large Surface Area-to-Volume Ratio Characteristics of All Cells A surrounding membrane Protoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA  Cell Types Prokaryoti c Eukaryoti c Prokaryotic Cells First cell type on earth Cell type of Bacteria and Archaea  Prokaryotic Cells No membrane bound nucleus Nucleoid = region of DNA concentration Organelles not bound by membranes Eukaryotic Cells Nucleus bound by membrane Include fungi, protists, plant, and animal cells Possess many organelles Protozo an Representative Animal Cell Representative Plant Cell  Organelles Cellular machinery Two general kinds – Derived from membranes – Bacteria-like organelles Bacteria-Like Organelles Derived from symbiotic bacteria Ancient association Endosymbiotic theory – Evolution of modern cells from cells & symbiotic bacteria  Plasma Membrane Contains cell contents Double layer of phospholipids & proteins  Phospholipids Polar – Hydrophylic head – Hydrophobic tail Interacts with water  Movement Across the Plasma Membrane A few molecules move freely – Water, Carbon dioxide, Ammonia, Oxygen Carrier proteins transport some molecules – Proteins embedded in lipid bilayer – Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins Membrane Proteins 1. Channels or transporters – Move molecules in one direction 2. Receptors – Recognize certain chemicals Membrane Proteins 3. Glycoproteins – Identify cell type 4. Enzymes – Catalyze production of substances  Cell Walls Found in plants, fungi, & many protists Surrounds plasma membrane Cell Wall Differences Plants – mostly cellulose Fungi – contain chitin  Cytoplasm Viscous fluid containing organelles components of cytoplasm – Interconnected filaments & fibers – Fluid = cytosol – Organelles (not nucleus) – storage substances  Cytoskeleton Filaments & fibers Made of 3 fiber types – Microfilaments – Microtubules – Intermediate filaments 3 functions: – mechanical support – anchor organelles – help move substances A = actin, IF = intermediate filament, MT = microtubule  Cilia & Flagella Provide motility Cilia – Short – Used to move substances outside human cells Flagella – Whip-like extensions – Found on sperm cells Basal bodies like centrioles Cilia & Flagella Structure Bundles of microtubules With plasma membrane  Centrioles Pairs of microtubular structures Play a role in cell division Membranous Organelles Functional components within cytoplasm Bound by membranes  Nucleus Control center of cell Double membrane Contains – Chromosomes – Nucleolus  Nuclear Envelope Separates nucleus from rest of cell Double membrane Has pores  DNA Hereditary material Chromosomes – DNA – Protiens – Form for cell division Chromatin  Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes Endoplasmic Reticulum Helps move substances within cells Network of interconnected membranes Two types – Rough endoplasmic reticulum – Smooth endoplasmic reticulum Rough Endoplasmic Reticulum Ribosomes attached to surface – Manufacture protiens – Not all ribosomes attached to rough ER May modify proteins from ribosomes  Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules – Carbohydrates – Lipids  Golgi Apparatus Involved in synthesis of plant cell wall Packaging & shipping station of cell Golgi Apparatus Function 1. Molecules come in vesicles 2. Vesicles fuse with Golgi membrane 3. Molecules may be modified by Golgi Golgi Apparatus Function (Continued) 4. Molecules pinched-off in separate vesicle 5. Vesicle leaves Golgi apparatus 6. Vesicles may combine with plasma membrane to secrete contents  Lysosomes Contain digestive enzymes Functions – Aid in cell renewal – Break down old cell parts – Digests invaders  Vacuoles Membrane bound storage sacs More common in plants than animals Contents – Water – Food – wastes Bacteria-Like Organelles Release & store energy Types – Mitochondria (release energy) – Chloroplasts (store energy) Mitochondria Have their own DNA Bound by double membrane  Mitochondria Break down fuel molecules (cellular respiration) – Glucose – Fatty acids Release energy – ATP  Chloroplasts Derived form photosynthetic bacteria Solar energy capturing organelle Photosynthesis Takes place in the chloroplast Makes cellular food – glucose Review of Eukaryotic Cells Review of Eukaryotic Cells Questions and Answers