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 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 DiatomAmoeba

Check out this interactive to get an idea of the scale of cells… n/cells/scale/ n/cells/scale/ How big is an e-coli bacteria? Which is bigger the influenza virus or hepatitis?

7-1: Life is Cellular 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 White Blood Cell attacking Bacteria

7-1: Life is Cellular Prokaryotes No nucleus (DNA is free- floating 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 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 Muscle cells: Nuclei are stained purple.

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 –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