Chapter 2 - The Cell (1) tuesday sep 17.pdf - Cell Biology

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 ___cells__ 2. The cell is the smallest structural and functional unit of life 3. Cells arise only from the growth and division of preexisting cells P...

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 ___cells__ 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 _size of the cell______ 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 __versatile____ Eukaryotic Cell. Eukaryotic Cell. Nucleus The nucleus contains most DNA therefore 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 __double____ membrane Ribosomes Ribosomes are particles made of ribosomal RNA and protein Function is to carry out ______protein synthesis_____: 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 ( Golgi complex) Lysosomes Vesicles Plasma membrane  Endoplasmic Reticulum (ER) Rough ER (RER): – Ribosome-studded ( attached to the membrane) – Makes __proteins___ that become part of cell membranes or are secreted from cell Smooth ER (SER): – Synthesizes __lipids___ 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 ( Recycling center of the orgenelles) 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 __double_____ 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 __double_____ 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 and pigments Cell Wall Provides Support and structure Protection Perforated with ____plasmodesmatas__________ 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 - Found between cells. 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?