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Transcript
Chapter 7: Cell Structure and Function 7-1: Life is Cellular • The Discovery of the Cell – Robert Hooke coins the term “cell” to describe sections of cork that he sees through his microscope in 1665. Left: Hooke’s cork cells Right: cork cells by electron microscope 7-1: Life is Cellular Around the same time Anton van Leeuwenhoek finds “animacules” in pond water. 7-1: Life is Cellular This leads to the Cell Theory: 1. All living things are composed of cells. 2. Cells are the basic unit of living things. 3. New cells are produced from existing cells. 7-1: Life is Cellular • Cells come in all shapes and sizes – a typical cell is 5-50 micrometers in diameter – smallest cells (bacteria) are 0.2 micrometers across – Biggest cells (ex: amoeba) can be 1000 micrometers across – visible with the naked eye Diatom Amoeba Check out this interactive to get an idea of the scale of cells… • http://learn.genetics.utah.edu/content/begi n/cells/scale/ How big is an e-coli bacteria? Which is bigger the influenza virus or hepatitis? 7-1: Life is Cellular White Blood Cell attacking Bacteria Two Broad Categories of Cells • Prokaryotes and Eukaryotes – Greek roots • “pro-” means first or before • “eu-” means true • “-karyon” means kernel – Both types have cell membranes and DNA – Prokaryotes are much smaller than eukaryotes – Prokaryotes vastly outnumber eukaryotes 7-1: Life is Cellular Prokaryotes • No nucleus (DNA is freefloating in the cytoplasm) • Bacteria are prokaryotes Streptococcus bacteria 7-1: Life is Cellular Eukaryotes • Contains nucleus (DNA is contained within the nucleus) • Single-celled organisms and all multicellular organisms • Often perform specific functions White blood cell among red blood cells 7-2: Eukaryotic Cell Structure • How is a cell like a factory? – Organelles perform specific, repetitive tasks • “Organelles” means little organs Organelles inside a cell 7-2: Eukaryotic Cell Structure Muscle cells: Nuclei are stained purple. Nucleus – Contains DNA (instructions for making proteins) – Control center for cellular activities – Nuclear anatomy • Nuclear envelope (porous) • Chromatin (DNA attached to proteins) – Chromatin becomes chromosomes during cell division 7-2: Eukaryotic Cell Structure Ribosomes – Made of RNA and proteins – Ribosomes make proteins (important!) • Use amino acids to make chains that form proteins 7-2: Eukaryotic Cell Structure Endoplasmic Reticulum – Lipid components of cell membrane and proteins that get exported from the cell are made on the endoplasmic reticulum – Two types of ER • Smooth ER – synthesis of membrane lipids and detoxification of drugs • Rough ER – Called “rough” because of ribosomes on surface – proteins bound for export are chemically modified 7-2: Eukaryotic Cell Structure Golgi Apparatus (AKA Golgi Body) – It’s a stack of membranes (like pancakes) – Final touches on proteins after they leave the endoplasmic reticulum, before they leave the cell – Lysosomes are made by the Golgi apparatus 7-2: Eukaryotic Cell Structure Protein Synthesis 7-2: Eukaryotic Cell Structure Lysosomes – Made by the Golgi apparatus – Contain digestive enzymes – garbage men of the cell 7-2: Eukaryotic Cell Structure Vacuoles – Saclike structures that store materials like water, salts, proteins, and carbohydrates – Prominent feature of plant cells 7-2: Eukaryotic Cell Structure Mitochondria – Power House of the cell – Energy from glucose is converted into energy that organelles can use – Inherited from your mother 7-2: Eukaryotic Cell Structure Chloroplasts – Organelles of photosynthesis (found in plants and other photosynthetic organisms) – Contain green pigment, called chlorophyll 7-2: Eukaryotic Cell Structure Organelle DNA – Mitochondria and Chloroplasts have their own DNA!? American biologist Lynn Margulis has suggested that these organelles are descendants of ancient, independent prokaryotes. The ancestors of modern-day eukaryotes may have developed symbiotic relationships with such prokaryotes millions of years ago. Mitochondrion Prokaryote Endosymbiotic theory 7-2: Eukaryotic Cell Structure Cytoskeleton – A network of protein filaments that help to support eukaryotic cells (also help some cells to move) – Composed primarily of microfilaments and microtubules Microfilaments in red Microtubules in green