Transcript Biology
Levels of Organization Least complex Most Complex Atoms Molecules Cells Tissue Organ Organ System Organism Population Community Ecosystem Biosphere Slide 1 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular The Discovery of the Cell The Discovery of the Cell The invention of the microscope allowed us to make cells visible. Slide 2 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular The Discovery of the Cell Early Microscopes In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material. In Holland around the same time, Anton van Leeuwenhoek used a microscope to observe living things. Cells are the basic units of life. Slide 3 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular The Discovery of the Cell The Cell Theory 1838 -1855: Scientists, such as Schleiden Schwann, and Virchow as well as other biologists observed the cell, developed theories, and summarized their ideas. These discoveries led to the cell theory. Slide 4 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular The Discovery of the Cell The Cell theory states: • All living things are composed (made up of) of cells. • Cells are the basic units of structure and function in living things. • New cells are produced from existing cells. Slide 5 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular MICROSCOPES LIGHT MICROSCOPE (LM) LM - Works by passing visible through a specimen, such as an microorganism or a piece of plant or animal tissue Micrograph- a photo taken through a microscope Magnification - the increase in the actual size Resolving power: a measure of the clarity Slide 6 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Exploring the Cell MICROSCOPES Electron Microscopes (EM) - 2 Types Electron microscopes reveal details 1000 times smaller than those visible in light microscopes. Electron microscopy can be used to visualize only nonliving, preserved cells and tissues. Slide 7 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Exploring the Cell 1. TRANSMISSION ELECTRON MICROSCOPES (TEMS) • Used to study cell structures and large protein molecules • Used to study the details of the internal cell structure Slide 8 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Exploring the Cell 2. SCANNING ELECTRON MICROSCOPES (SEMS) • Produce three-dimensional images of cells • Specimens do not have to be cut into thin slices • Used to study the external cell structure Slide 9 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Exploring the Cell Scanning Electron Micrograph of Neurons Slide 10 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Prokaryotes and Eukaryotes CELL TYPES Prokaryotes and Eukaryotes Contain small organs called organelles Slide 11 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Prokaryotes & Eukaryotes All cells, Prokaryotic & eukaryotic have three common features. Nucleus, which contains DNA, the genetic material contained in one or more chromosomes and located in a non-membrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes Slide 12 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Three main parts Plasma membrane, a phospholipid bilayer with proteins; separates the cell from the surrounding environment; functions as a selective barrier for the import and export of materials Cytoplasm, the rest of the material of the cell within the plasma membrane, excluding the nucleoid region or nucleus, that consists of a fluid portion called the cytosol Slide 13 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Prokaryotes Prokaryotic cells •Plasma membrane •Cytoplasm •Nucleoid region •DNA •Ribosomes •Pili •Flagellum Smaller and simpler eukaryotes than Bacteria are prokaryotes Slide 14 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Eukaryotic Cells Eukaryotes Plant and Animal Cells More complex - Many cells are highly specialized.Plants, animals, fungi, and protists are eukaryotes Slide 15 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular PLANT CELL Nucleus CYTOSKELEYTON: Microtubules, Intermediate filaments, & microfilaments Slide 16 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Plant Cells PLANT CELLS contain chloroplasts, a cell wall, & a central vacuole, which are NOT found in animal cells. Chloroplasts are plant cell organelles that contain chlorophyll and the enzymes required for photosynthesis. Mitochondria - (singular = mitochondrion) All eukaryotic cells contain mitochondria, often many hundreds per cell. They harvest energy from food during cellular respiration and generate ATP (energy). Slide 17 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Cytoskeleton CYTOSKELETON: Structural Support •Microfilaments - solid, helical rods composed of globular proteins called actin (shape & movement) •Intermediate filaments - made of fibrous proteins, for reinforcement and anchoring •Microtubules - straight, hollow tubes made up of globular proteins called tubulin ( tubulin pairs) Together they maintain cell shape, anchor organelles, and cause cell movement. Slide 18 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Cell Movement Cell Movement: Cilia and Flagella Cilia -short, numerous appendages • On cell lining the human windpipe Flagella - long, less numerous appendages • sperm Both are composed of a core of microtubules; a ring of 9 - microtubule doublets that surround a central pair of microtubules; combined called 9 + 2. The 9-doublets extend into an anchoring structure called a basal body (identical to centrioles). The basal body has 9 microtubule triplets. The microtubule doublets are connected by dynein arms that help them bend and move (H - page 65) Slide 19 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Endomembrane system Endomembrane system (4.14) -Transport •Nucleus •nuclear envelope •endoplasmic reticulum (ER)- both •Golgi apparatus •Transport vesicles (develop into lysosomes and vacuoles. •plasma membrane. Slide 20 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular Cell Junctions Extracellular Matrix 1. Tight junctions: bind cells together 2. Anchoring junctions (gap): attach adjacent cells to each other 3. Communicating junctions : channels that allow water and other small molecules to flow between cells. Communicating Anchoring junctions Slide 21 of 31 Copyright Pearson Prentice Hall