Chapter 6 - Chapter 6 6.1 Biologists use microscopes and...

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Chapter 6 6.1 – Biologists use microscopes and the tools of biochemistry to study cells - In a light microscope (LM) , visible light is passed through the specimen and then through glass lenses. - 3 important parameters in microscopy are magnification, resolution, and contrast. - Organelles – the membrane-enclosed structures within eukaryotic cells. - Electron microscope (EM) – focuses a beam of electrons through the specimen or onto its surface. - The scanning electron microscope (SEM) is especially useful for detailed study of the topography of a specimen. - The transmission electron microscope (TEM) is used to study the internal structure of cells. - Cell fractionation – takes cells apart and separates major organelles and other subcellular structures from one another. 6.2 – Eukaryotic cells have internal membranes that compartmentalize their functions - Cells are the basic structural and functional units of every organism. - Prokaryotic: Bacteria and Archaea - Eukaryotic: Protists, Fungi, Animals, and Plants - Cytosol – a semifluid, jellylike substance, in which subcellular components are suspended. - Chromosomes – carry genes in the form of DNA. - Ribosomes - tiny complexes that make proteins according to instructions from the genes. - In a eukaryotic cell, most of the DNA is in an organelle called the nucleus, which is bounded by a double membrane. - In a prokaryotic cell, the DNA is concentrated in a region that is not membrane- enclosed, called the nucleoid. - Cytoplasm – the interior of either type of cell. - Plasma membrane – functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell. 6.3 – the eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes - The nucleus contains most of the genes in the eukaryotic cell. - The nuclear envelope encloses the nucleus, separating its content from the cytoplasm. It is a Double Membrane - Nuclear lamina – a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope. - Within the nucleus, the DNA is organized into discrete units called chromosomes , structures that carry the genetic information. - The complex of proteins making up chromosomes is called chromatin. - A prominent structure within the nondividing nucleus in the nucleolus, which appears through the electron microscope as a mass of densely stained granules and fibers adjoining part of the chromatin.
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- Ribosomes, which are complexes made of ribosomal RNA and protein, are the cellular components that carry out protein synthesis. 6.4 – The endomembrane system regulates protein traffic and performs metabolic
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Chapter 6 - Chapter 6 6.1 Biologists use microscopes and...

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