Bio181FinalExamGuide5 - ribosome an organelle in cells that...

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- ribosome - an organelle in cells that assembles proteins . Ribosomes are composed of ribosomal RNA and ribosomal proteins . It translates messenger RNA (mRNA) into a polypeptide chain (e.g., a protein ). Ribosomes can float freely in the cytoplasm or bind to the endoplasmic reticulum , or to the nuclear envelope . b. molecular composition and organization of a chromosome: - histone proteins - the chief proteins of chromatin . They act as spools around which DNA winds and they play a role in gene regulation . While histones are found in the nuclei of eukaryotic cells , bacteria do not have histones. Histone proteins are among the most highly conserved proteins in eukaryotes, emphasizing the important role they play in the biology of the nucleus. - DNA - is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus . All known cellular life and some viruses have DNA. DNA is a long polymer of nucleotides (a polynucleotide) that encodes the sequence of amino acid residues in proteins , using the genetic code . - non-histone proteins - associated to nucleosomes in actively transcribed genes . Stimulates transcription by altering the interaction of histone H1 with nucleosomes to maintain a
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This note was uploaded on 04/21/2008 for the course BIO 181 taught by Professor Milton during the Spring '08 term at N.C. State.

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Bio181FinalExamGuide5 - ribosome an organelle in cells that...

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