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Cell Structure & Function. Chapter 4. The History of Cell Biology. Robert Hooke: 1665 Created the first microscope Studied cork and saw “little boxes”. Robert Hooke. Anton von Leeuwenhoek: 1673 Dutch trader, considered to be the father on microbiology Made better lens.
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Cell Structure & Function Chapter 4
The History of Cell Biology Robert Hooke: 1665 Created the first microscope Studied cork and saw “little boxes”
Anton von Leeuwenhoek: 1673 • Dutch trader, considered to be the father on microbiology • Made better lens The History of Cell Biology
The History of Cell Biology • Protists: Spirogyra, Vorticella • “Wee little beasties”
The Cell Theory • All living organisms are composed of one or more cells. • Cells are the basic units of structure and function in an organism • Cells come only from the reproduction of existing cells.
Characteristics of Life: • organized parts • obtain energy from surroundings • metabolism • change with time • respond to their environments • reproduce • homeostasis • Relatedness
Cell Diversity • Cell Shape: The diversity of cell shapes reflects the different functions of cells. ex. nerve cell, muscle, skin. • Cell Size: limited by its surface area-to-volume ratio
Basic Parts of the Cell • Plasma Membrane: outer covering, barrier controlling access to cell • Cytoplasm: all the goo and lumps inside a cell except the nucleus • Nucleus/Nucleoid Region: DNA: control/heredity
Two Basic Types of Cells Prokaryotes: Eukaryotes: membrane-bound organelles upper-limit on size is much greater than prokaryotes membrane-bound organelles increases the surface area within the cell making it more efficient • no membrane-bound organelles, • necessary enzyme systems are imbedded on the inside of the plasma membrane. • upper limit of size is smaller than eukaryotes
Cellular Organization Colonies True Multicellularity As organisms evolved, their cells became more specialized eventually were unable to survivie independently groups of cells took on specific roles Tissues Organs Organ Systems Organism • collections of genetically identical cells • live together in a connected group • few cell activities are coordinated
Plasma Membrane • phospholipids: part polar (like water), part non-polar (lipid or “anti-water”) • bilayer • Membrane Proteins: integral proteins are “integrated” into the membrane to some degree • some, emerge from only one side like cell-surface markers: cell-cell recognition, dock for viruses • others, go clear across the bilayer of membrane like receptor or transport proteins. • active transport proteins • passive transport protein channels for ions or large molecules. • still others, lie on only one side of the membrane but are not embedded into it. For example, enzymes.
Nucleus • nucleoplasm • DNA in the form of chromosomes • DNA is copied into RNA in nucleus
Nuclear Envelope • double membrane (two bilayers) with protein pores
Nucleolus • site of RNA synthesis
Mitochondria • inner and outer membranes • outer separates it from cytosol • inner is folded to increase surface area • break down glucose to make ATP • contains its own DNA
Ribosomes: • protein + RNA • organize production of protein • free ones make protein to be kept by cell • attached ones make protein for export
Endoplasmic Reticulum: “highway” • Rough endoplasmic reticulum • interconnected flattened sacs • covered with ribosomes • digestive glands and antibody-producing cells • Smooth Endoplasmic Reticulum • lacks ribosomes so looks smooth • builds lipids such as cholesterol • ex. sex hormones • releases Calcium (Ca) • detoxify /s.ER production / drug tolerance
Golgi Apparatus • system of flattened sacs • ER Golgi Vesicles ? export by exocytosis • Golgi modifies, adds “address labels,” packages
Vesicles • small, spherical sacs, single membrane, classified on contents • Lysosomes: hydrolytic enzymes • Peroxisomes: different enzyme hydrogen peroxide • Food vacuoles: store food • Contractile Vacuoles: contract to rid cell of excess water
Cytoskeleton • network of thin tubes and filaments that crisscross cytosol • used like tent poles to support structure • used as internal tracks on which items move or anchor
Cilia and Flagella • membrane on outer surface, microtubules 9 + 2 • Cilia: short and numerous, in ear: vibrate with sound, protists use to “row”, get food by sweeping into “mouth” • Flagella: long and few in #, propulsion
Centrioles • two short cylinders of microtubules at right angles to each other • animal cells only • organize cell division • basal bodies have same structure (cilia and flagella)
Cell Walls • rigid • Contain cellulose • It lays outside plasma membrane • pores allow water, ions and some molecules to enter/exit
Large Central Vacuole • Stores water, enzymes, metabolic wastes etc. • formed by smaller vacuoles fusing together • when dry, vacuole loses water, cells shrink, plant wilts
Plastids • Unique feature of plant cells • double membrane • DNA • Examples: chloroplasts, chromoplasts, & leucoplasts
Types of Plastids • Chloroplasts • chloroplast system of flattened, membranous sacs called thylakoids • chlorophyll in thylakoids captures light energy • Green pigment • descendents of ancient prokaryotes • endosymbiosis
Types of Plastids • Chromoplasts • contain colorful pigments and may or may not take part in photosynthesis • carotene in carrots • red, purple, yellow, or white pigments in flower petals
Types of Plastids • Other Plastids • Amyloplasts: store starch • Proplastid: common precursor to all the above