Chapter 2 - The Cell - PDF

Chapter 2 The Cell: An Overview What is the basic unit of life? The Cell Theory states: 1. All organisms are composed of one or more _____ 2. The cell is the smallest structural and functional unit of life 3. Cells arise only from the growth and division of preexisting cells Prokar...

Chapter 2 The Cell: An Overview What is the basic unit of life? The Cell Theory states: 1. All organisms are composed of one or more _____ 2. The cell is the smallest structural and functional unit of life 3. Cells arise only from the growth and division of preexisting cells Prokaryotic vs. Eukaryotic DNA Prokaryotic – one circular double strand DNA Eukaryotic – many linear double stranded DNA Eukaryotic Prokaryotic Why are eukaryotic cells larger than prokaryotic cells?? Skin cell Bacteria  Surface to Volume Ratios This determines the _______ Prokaryotic cell Fig. 2-15, p. 33 Prokaryotes No nucleus or membrane-bound organelles Circular DNA in an unbound region - nucleoid Ribosomes Cell wall Capsule Plasma membrane for respiration and photosynthesis Flagella and pili Diversity of Prokaryotes Use variety of substances as energy and carbon sources and to synthesize almost all required organic molecules Vastly outnumber all other types of organisms Live successfully in almost all regions of Earth’s surface Prokaryotes are extremely _______. Eukaryotic Cell. Eukaryotic Cell. Nucleus The nucleus contains most genes The nuclear envelope encloses the nucleus Nuclear pore complex DNA and proteins form genetic material called chromatin Chromatin condenses to form discrete chromosomes The nucleolus is located within the nucleus and is the site of ribosomal RNA synthesis  Nuclear Envelope ______ membrane Ribosomes Ribosomes are particles made of ribosomal RNA and protein Function is to carry out ___________: Free ribosomes – In cytosol Bound Ribosomes - On outer surface of ER or nuclear envelope Endomembrane System Collection of interrelated internal membranous sacs that divide cell into functional and structural compartments called organelles Regulates protein traffic Performs metabolic functions Endomembrane System Made up of: Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vesicles Plasma membrane  Endoplasmic Reticulum (ER) Rough ER (RER): – Ribosome-studded – Makes _____ that become part of cell membranes or are secreted from cell Smooth ER (SER): – Synthesizes _____ and breaks down toxic substances – No ribosomes attached  Rough versus Smooth ER RER SER  Golgi Complex Flattened membranous sacs Chemically modifies proteins made in rough ER Sorts finished proteins into transport vesicles to be secreted from cell or embedded in plasma membrane or lysosomes Lysosomes Membranous sac of hydrolytic enzymes that can digest macromolecules Recycle the cell’s own organelles and macromolecules – Also involved in  Vesicle Traffic cis-Golgi trans-Golgi Vesicles: Exocytosis vs. Endocytosis Mitochondria Mitochondria is the site for cellular respiration Have own DNA Make proteins from free ribosomes _______ membrane Cristae Mitochondrial matrix The Cytoskeleton Supportive structure Built from: – Microtubules – Intermediate filaments – Microfilaments Function Support and shape cells Interacts with motor proteins = Motility Monorails for vesicle trafficking Regulate biochemical activities  Major Components of the Cytoskeleton Microtubules Intermediate filaments Microfilaments Thickest Thinnest tubulin keratin actin Centrosomes and centrioles Microtubules grow out from a centrosome The centrosome is a microtubule organizing centre In animal cells, the centrosome has a pair of centrioles  Motor Protein: Kinesin Alpha helical Beta pleated sheets Structure of a Eukaryotic Flagellum Microtubules Dynein protein Whip-like action Flagellar and Ciliary Beating Patterns Peroxisomes Specialized metabolic compartments bounded by a single membrane Converts hydrogen peroxide to water Chloroplasts Type of plastid Chloroplast is the site for photosynthesis Have own DNA Make proteins from free ribosomes _______ membrane Grana Vacuoles Food vacuoles are formed by phagocytosis Contractile vacuoles pump excess water out of cells Central vacuoles (plants) hold organic compounds and water Cell Wall Provides Support Protection Perforated with ______________ Animal Cell Surface Cell surface molecules aid in cell contact, communication and organization 1. Cell Adhesion Molecules 2. Cell Junctions 3. Extracellular Matrix Cell Adhesion Molecules Glycoproteins embedded in plasma membrane Maintain body form and function Attach and detach during development Cell recognition molecule Adhesion site for pathogens  Cell Junctions in Animal Cells Tight junctions - membranes of neighboring cells are pressed together, so prevents leakage of extracellular fluid Anchoring junctions (Desmosomes) - fasten cells together into strong sheets Gap junctions (communicating junctions) - provide cytoplasmic channels between adjacent cells Cell Junctions in Animal Cells Extracellular Matrix Putting it into perspective 1. What are the basic features of a cell? 2. What are the differences between prokaryotic versus eukaryotic cells. 3. What are some other cellular structures 4. What are the features of the animal cell surface?