Transcript Document
A Tour of the Cell Cell Biology Outline • Cell Structure and Organelles • Electron micrographs, figures and function • Cell Molecular Components Structure of Animal Cells Cell Video Protection and Controlling Entry Cell Membrane Cell Membrane Composition • Plasma membrane encloses cell and cell organelles • Made of hydrophobic and hydrophillic components – Semi-permeable and fluid-like – “lipid bilayer” Cell Membrane Composition • Integral proteins interact with “lipid bilayer” – Passive transport pores and channels – Active transport pumps and carriers – Membrane-linked enzymes, receptors and transducers • Sterols stabilize the lipid bilayer – Cholesterol Cell Wall Function: provides support and protection to the cell membrane Found outside the cell membrane in plant cells Cellulose is porous, rigid and strong Control of the Cell Cell Organelles • Nucleus Nickname:“The Control Center” Function: holds the DNA Parts: Nucleolus: dark spot in the middle of the nucleus that helps make ribosomes Chromatin: loosely coiled DNA (cells not dividing) two types – hetero__ –dark - eu__ - light Organelles that Provide Energy •Mitochondria –Double membrane –Mitochondrial (maternal) DNA, –replicates independently from the cell “Power House” of the cell •Food converted into energy –Adenosine triphosphate (ATP) •Consumes Oxygen, produces CO2 Chloroplast Nick name: Sugar Daddies Function: traps energy from the sun to produce food for the plant cell Green in color because of chlorophyll, which is a green pigment Double membrane structure Unique DNA, replicates independently from the cell Packaging and Receiving • Endoplasmic Reticulum (ER) – Site where cell membrane and exported material is made – Rough ER (+ Ribosomes) • Make proteins to be shipped out – Smooth ER Make lipids to be shipped out Ribosomes -sites of protein synthesis. -not membrane-bound - consists of a small and larger subunit, - consists of ribosomal RNA (rRNA) and some 50 structural proteins. -Bound ribsosomes make proteins for export, non-bound ribosomes make proteins for internal use -Most plentiful organelle in the cell Lysosomes: circular, but bigger than ribosomes Nickname: “Clean-up Crews” Function: to break down food into particles the rest of the cell can use and to destroy old cells Intracellular digestion Releases nutrients Breakdown of waste Autolysis Self-destruction of damaged cells: –auto = self, lysis = break –lysosome membranes break down –digestive enzymes released –cell decomposes –cellular materials recycle Golgi Complex/Apparatus Nickname: The shippers Function: packages, modifies, and transports materials to different location inside/outside of the cell Appearance: stack of pancakes Note the direction of the flow Of the material into the cis and Out the trans. Vessicles • Peroxisomes – • Hydrogen Peroxide generated and degraded to detoxify the cell Vessicles – • Material transport Vacuole - • stores water Plastids - Leucoplasts, aka amyloplasts store starch, protein or oils. Chromoplasts store bright color pigments Inter mediate filaments Microfilaments Microtubules Structural proteins for shape and strength Microfilaments – Thin filaments composed of the protein actin: provide additional mechanical strength interact with proteins for consistency Pairs with thick filaments of myosin for muscle movement Intermediate – Mid-sized between microfilaments and thick filaments: durable (collagen) strengthen cell and maintain shape stabilize organelles stabilize cell position Microtubules –Large, hollow tubes of tubulin protein: attach to centrosome strengthen cell and anchor organelles change cell shape move vesicles within cell (kinesin and dynein) form spindle apparatus Form cilia and flagella Centrioles in the Centrosome Centrioles form spindle apparatus during cell division Centrosome: cytoplasm surrounding centriole Cell Adhesion Gycocalyx -vecro-like ogliosaccharides that bind and hold to other cells Tight Junctions - seal/adhere cells together Adherens Junctions - actin filaments that bind and hold cells together Gap Junction -trans-cellular protein channels Desmosome -proteins the anchor intermediate filaments from neighbouring cells together