* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
All forms of life share common properties (3) Growth and development (1) Order (4) Energy processing (2) Reproduction (6) Regulation (5) Response to the environment (7) Evolutionary adaptation The Cell Theory • Cells are the basic unit of structure and function in an organism • All cells come from prexisting cells Robert Hooke (17th century) – Anton van Leeuwenhoek (later 17th century) – Observed microscopic organisms; organisms can be comprised of just a single cell Schleiden (1830s) – Coined the phrase ‘cells’ All plants are made of cells Schwann (1839) – All animals are made of cells Cells: A Sense of Scale 10 m Most cells and their structures are too small to view with the naked eye. Length of some nerve and muscle cells 0.1 m Chicken egg Unaided eye Human height 1m 1 cm Frog egg Most plant and animal cells 10 µm Nucleus Most bacteria 1 µm 100 nm Mitochondrion Smallest bacteria Viruses Ribosomes Scanning EM of Enteric bacteria on villi of small intestine 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms Electron microscope 100 µm Light microscope 1 mm Microscopes reveal the world of the cell Light microscope - 1,000x magnification, limited resolution – Magnification is the increase in the apparent size of an object. – Resolution is a measure of the clarity of an image -- it is the ability of an instrument to show two close objects as separate. Transmission electron (TEM) - detail of interior structures Scanning electron (SEM) - surface structures ‘3D image’ – Electron microscopes DO NOT allow observations of living specimens. © 2012 Pearson Education, Inc. Light Microscopy Scanning electron microscopy (SEM) Cilia Scanning electron microscopy (SEM) Longitudinal section of cilium Transmission electron Microscopy (TEM) 1 µm Cross section of cilium 1 µm 2 Basic Cell Types: Prokaryote and Eukaryote Bacteria and archaea are prokaryotic cells. – Prokaryotes have no nucleus and no true organelles. Eukaryotic cells = protists, plants, fungi, animals All cells have: – – a plasma membrane – one or more chromosomes (DNA) – Ribosomes – cytoplasm Only Eukaryotic cells have a – membrane-bound nucleus and – number of other organelles. Outside of cell Carbohydrate side chain Hydrophilic region Inside of cell 0.1 µm Hydrophobic region Hydrophilic region TEM of a plasma membrane Phospholipid Proteins Structure of the plasma membrane Prokaryotic Cell Structure Unicellular Cell Wall surrounds plasma membrane Fimbriae – Ribosome – Nucleoid Plasma membrane A typical rod-shaped bacterium Peptidoglycan (mix of protein and carbohydrates) – NO Cellulose (plants cells) – Provides structure and support Cell wall Bacterial chromosome Composed of lipids, carbohydrates and protein Nucleiod region Capsule – Flagella One large circular chromosome that is attached to one area of the plasma membrane Flagella (Flagellum) – Used for directed movement – Rotate like propellors Capsule Tonsil cell Bacterium Endospore Flagella Fimbriae h. a. b. c. d. g. e. A typical rod-shaped bacterium Label The Following Structures: f. Concept Check The three domains of life described by biologists today include the bacteria, the archaea, and the eukarya (all other forms of life). What is the basic difference between the eukarya or eukaryotes and the prokaryotes (archaea and bacteria)? a) The prokaryotes do not have a plasma membrane surrounding the cell. b) The prokaryotes use RNA and not DNA to pass on the genetic message. c) The interior of the cell of eukaryotes is divided by internal membranes into specialized compartments. d) The eukaryotes engage in cellular metabolism while the prokaryotes do not. © 2012 Pearson Education, Inc. Answer The three domains of life described by biologists today include the bacteria, the archaea, and the eukarya (all other forms of life). What is the basic difference between the eukarya or eukaryotes and the prokaryotes (archaea and bacteria)? – The interior of the cell of eukaryotes is divided by internal membranes into specialized compartments. © 2012 Pearson Education, Inc. Interpreting Data Images generated by the Hubble telescope or the planetary probes like Voyager telescope give us a very limited view of the universe. Likewise, looking at cells under a light microscope is limited by the ability to resolve cellular parts. Which of the following cell parts are visible under a light microscope? – ribosomes – large macromolecules – microtubules – mitochondria—just barely © 2012 Pearson Education, Inc. Answer Images generated by the Hubble telescope or the planetary probes like Voyager telescope give us a very limited view of the universe. Likewise, looking at cells under a light microscope is limited by the ability to resolve cellular parts. Which of the following cell parts are visible under a light microscope? – mitochondria—just barely © 2012 Pearson Education, Inc.