chapter3

Cell Structure: Cell Structure One more lecture and then you will be tested! PowerPoint Presentation: What is this girl eating? A dish of delicious plant cells!: A dish of delicious plant cells! …and something else. PowerPoint Presentation:  cheetos? PowerPoint Presentation: Fig. 3-3a, p. 45 450X PowerPoint Presentation: Fig. 3-3b, p. 45 1000X PowerPoint Presentation: Fig. 3-3c, p. 45 +1000X PowerPoint Presentation: No one knew cells existed until microscopes were invented 1600s: van Leeuwenhoek’s microscope PowerPoint Presentation: 1600s: Robert Hooke improved the microscope and coined the term “cell” 1839: Matthias Schleiden and Theodore Schwann realized cells were alive and proposed the cell theory PowerPoint Presentation: We went from this…. …to this In 414 years! So, what are we going to have in 2428? For example, It took 70 or so years to have computers. PowerPoint Presentation: Cell theory is a fundamental theory of biology Cell theory All organisms consist of one or more cells The cell is the smallest unit of life Each new cell arises from another cell A cell passes hereditary information to its offspring PowerPoint Presentation: Most cells are visible only with the help of microscopes Different types of microscopes use light or electrons to reveal different details of cells PowerPoint Presentation: Light microscope Fluorescence microscope Transmission electron microscope Scanning electron microscope PowerPoint Presentation: 10 μ m A Light micrograph. A phase-contrast microscope yields high-contrast images of transparent specimens, such as cells. B Light micrograph. A re fl ected light microscope captures light re fl ected from opaque specimens. C Fluorescence micrograph. The chlorophyll molecules in these cells emitted red light (they fl uoresced) naturally. D A transmission electron micrograph reveals fantastically detailed images of internal structures. E A scanning electron micrograph shows surface details of cells and structures. SEMs may be artificially colored to highlight certain details. PowerPoint Presentation: human eye (no microscope) largest organisms small animals humans frog eggs 100 µm 1 mm 1 cm 10 cm 1 m 10 m 100 m PowerPoint Presentation: light microscopes electron microscopes most eukaryotic cells molecules of life viruses mitochondria, chloroplasts most bacteria complex carbohydrates lipids DNA (width) proteins small molecules 0.1 nm 1 nm 10 nm 100 nm 1 µm 10 µm PowerPoint Presentation: Cells are the fundamental units of all life Most conspicuous parts: Plasma membrane , cytoplasm , and a region of DNA which, in eukaryotic cells only, is enclosed by a nucleus PowerPoint Presentation: The plasma membrane is basically a lipid bilayer balloon filled with fluid The nonpolar tails of both layers are sandwiched between the polar heads PowerPoint Presentation: A plasma membrane surrounds the cell and controls which substances move in and out Plasma membrane A cell’s outermost membrane Lipid bilayer Structural foundation of cell membranes; mainly phospholipids arranged tail-to-tail in a bilayer PowerPoint Presentation: A Phospholipids are the most abundant component of eukaryotic cell membranes. Each phospholipid molecule has a hydrophilic head and two hydrophobic tails. hydrophilic head two hydrophobic tails PowerPoint Presentation: An important part of homeostasis is maintaining the composition of cytoplasm, which differs from fluid outside the cell Cytoplasm Semifluid substance enclosed by a cell’s plasma membrane PowerPoint Presentation: A cell membrane is a mosaic of proteins and lipids (mainly phospholipids) that functions as a selectively permeable barrier that separates an internal environment from an external one Fluid mosaic model A cell membrane can be considered a two-dimensional fluid of mixed composition PowerPoint Presentation: Proteins associated with a membrane carry out most membrane functions Transport proteins passively or actively assist specific ions or molecules across a membrane Enzymes speed chemical processes Adhesion proteins help cells stick together Recognition proteins tag cells as “self” Receptor proteins bind to a particular substance outside the cell PowerPoint Presentation: Cell metabolism occurs in cytoplasm and internal compartments, including organelles Organelle Structure that carries out a specialized metabolic function inside a cell PowerPoint Presentation: Cells are classed as eukaryotes or prokaryotes based on how DNA is housed in the cell Nucleus Organelle with two membranes that holds a eukaryotic cell’s DNA Nucleoid Region of cytoplasm where DNA is concentrated in a prokaryotic cell PowerPoint Presentation: nuclear envelope mitochondrion DNA in nucleus nuclear pore rough ER with attached ribosomes Before the 90’s Components of an Animal Cell: Components of an Animal Cell Learn them for test! After the 90’s PowerPoint Presentation: Domains Bacteria and Archaea make up the prokaryotes Prokaryotes are single-celled organisms with no nucleus, but many have a cell wall and one or more flagella or pili PowerPoint Presentation: C The archaean Pyrococcus furiosus was discovered in ocean sediments near an active volcano. It lives best at 100°C (212°F), and it makes a rare kind of enzyme that contains tungsten atoms. PowerPoint Presentation: Biofilms are shared living arrangements among bacteria and other microbial organisms that provide various advantages to the community Biofilm Community of different types of microorganisms living within a shared mass of slime