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Transcript
Cell Structure and Function Attributes of cells A. Plasma membrane B. DNA C. Cytoplasm D. Obtain energy and nutrients from their environment Attributes of cells Cell size • 1. 1–100µm (0.00004 – 0.004 inches) • 2. Why is there a limit to cell size? • a. Surface-to-volume ratio • b. Distance from surface to center tallest trees adult human chicken egg frog embryo most eukaryotic cells mitochondrion most bacteria virus proteins diameter of DNA double helix atoms Attributes of cells Cell types 1. Prokaryotic—no nucleus, circular DNA, ribosomes 2. Eukaryotic—larger, nucleus, linear chromosomes, membranous organelles Prokaryotic Cells Have no membrane-bound organelles Include true bacteria On earth 3.8 million years Found nearly everywhere Spores in each breath; intestines Naturally in soil, air, hot springs nucleoid (DNA) ribosomes food granule prokaryotic flagellum plasma membrane cytoplasm cell wall Eukaryotic Cells Have numerous internal structures Various types & forms Plants, animals, fungi, protists Multicellular organisms nuclear pore chromatin (DNA) nucleus nucleolus nuclear envelope flagellum rough endoplasmic reticulum cytoplasm intermediate filaments plasma membrane ribosome lysosome microtubules smooth endoplasmic reticulum Golgi complex free ribosome vesicle mitochondrion vesicle microtubules (part of cytoskeleton) mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle cell wall rough endoplasmic reticulum plasma membrane nucleolus nucleus nuclear pore chromatin nuclear envelope intermediate filaments ribosomes free ribosome Eukaryotic cell structure Nucleus is control center of the cell 1. Membrane bound (nuclear envelope) 2. Contains nucleoli; synthesizes ribosomal RNA 3. DNA in chromosomes (DNA and proteins) nuclear envelope nucleolus nuclear pores chromatin nucleus nuclear pores chromatin chromosome 0.05 micrometers Eukaryotic cell structure Organelles Endoplasmic reticulum consists of folded membranes attached to the nucleus Rough ER is site of protein synthesis and protein secretion rough endoplasmic reticulum ribosomes 0.5 micrometers smooth endoplasmic reticulum 0.5 micrometers vesicles Eukaryotic cell structure Organelles (cont.) • Ribosomes assemble amino acid monomers into polypeptide chains • a. Associated with the ER • b. Composed of RNA and proteins ribosomes rough endoplasmic reticulum 0.5 micrometers vesicles smooth endoplasmic reticulum 0.5 micrometers Eukaryotic cell structure Organelles (cont.) Golgi apparatus are membranous sacs associated with ER • a. Processing and transport of proteins, lipids • b. Synthesis and transport of polysaccharides vesicles from ER vesicles leaving Golgi complex Golgi complex Eukaryotic cell structure Organelles (cont.) Lysosomes are Golgi-derived vesicles containing digestive enzymes vesicles from ER vesicles leaving Golgi complex Golgi complex Eukaryotic Cells: Organelles Energy sources for cell activities Mitochondria provide energy for cellular functions (respiration) • a. Membrane bound, numerous • b. Matrix/cristae • c. Have their own DNA and ribosomes; self-replicate 5 micrometers Eukaryotic Cells: Organelles Energy sources for cell activities • Chloroplasts—function in photosynthesis 1) Green—contain chlorophyll pigment 2) Stroma/grana (thylakoid stacks) 3) Have their own DNA and ribosomes; self-replicate 4) Up to 100 per cell Eukaryotic Cells: Organelles Cytoskeleton Internal infrastructure Surface structures extensions of the plasma membrane aid in movement of simple organisms actin subunits subunit tubulin subunit Prokaryotes & Eukaryotes Similarities & differences Both surrounded by plasma membrane, but very different Prokaryotes – Archaebacteria and Eubacteria Eukaryotes – everything else Evolution of Eukaryotic cell Endosymbiotic Hypothesis Similarities between bacteria, mitochondria and chloroplasts Self-reproducing by binary fission Size of organism and genome Single circular naked DNA Proportion of (G & C) to (A & T) Same sized ribosome Protein synthesis inhibited by antibiotics Enzymes for synthesis of DNA, RNA and protein Electron transport system Plant & Animal Cells Similarities Both constructed from eukaryotic cells Both contain similar organelles Both surrounded by cell membrane Plant & Animal Cells Differences Plants have • Cell wall – provides strength & rigidity • Have chloroplasts, photosynthetic Animals have • Other organelle not found in plants (lysosomes formed from Golgi) • Centrioles, important in cell division Brief Look at Viruses Viruses are acellular Not considered to be living Cause serious diseases in most organisms