hydrogen peroxide a potentially dangerous free radical Other enzymes within the

Hydrogen peroxide a potentially dangerous free

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hydrogen peroxide (a potentially dangerous free radical) Other enzymes within the peroxisome then break down H 2 O 2 to oxygen and water Peroxisomes Peroxisomes protect the cell from potentially damaging effects of free radicals produced during catabolism Their numbers are highest in metabolically active cells (the liver for example) Mitochondria Mitochondria are responsible for energy production Aerobic metabolism (cellular respiration) Number in cell varies with energy demand
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Mitochondria Mitochondria have a double membrane The outer membrane surrounds the organelle The inner membrane contains numerous folds called cristae What are the contents and structure of the nucleus? The Nucleus The nucleus is normally the largest and most conspicuous structure in the cell and is often the only visible structure under a light microscope The nucleus is the “ control center ” for cellular operations Nucleus The nucleus stores all the information needed to direct synthesis of proteins needed for body The nucleus determines the structure of the cell and what functions it can perform True or False All cells have one and only one nucleus? Nucleus Most cells have only one nucleus but exceptions do exist (some with more than one (skeletal muscle cells) some without (red blood cells) The nucleus is surrounded by a double membrane nuclear envelope and, at several locations, the envelope is connected with endoplasmic reticulum Nucleus Chemical communication between cytosol and nucleus occurs through nuclear pores. The pores are large enough to permit ions and small molecules to pass through but not proteins or DNA. Pores contain regulatory proteins that govern the transport of proteins and RNA in and out of nucleus Contents of the Nucleus The Nucleoplasm is the fluid contents of the nucleus and contains the Nuclear matrix, a matrix of fine filaments providing structural support The nucleoplasm also contains ions, enzymes, RNA and DNA nucleotides, small amounts of RNA, and DNA Nuclear contents Most nuclei contain nucleoli Transient nuclear organelles that synthesize ribosomal RNA and ribosomal subunits Are most prominent in cells that manufacture large amounts of proteins Liver, nerve, muscle cells (need large amounts of ribosomes) Nuclear contents Nucleoli are compos ed of RNA, enzymes, and proteins called histones Nucleoli form around portions of DNA that contain the instructions for producing ribosomal proteins and RNA when those instructions are being carried out What does DNA do? DNA DNA stores the instructions for protein synthesis DNA Organization DNA strands are coiled around histones (proteins) forming a complex known as a nucleosome .
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