BS 161 1st Edition Lecture 12 Outline of Last Lecture I Cell structure Outline of Current Lecture II Cell structure continued Current Lecture Antibiotics kill bacteria but don t kill animal cells because they do not react with animal cell components Eukaryotic cells has DNA in a nucleus that is bounded by a nuclear envelope nuclear membrane has membrane bound organelles mitochondria and chloroplast has cytoplasm in the region between the plasma membrane and nucleus The nucleus contains the cell s genetic material enclosed by the nuclear membrane separates it from the cytoplasm nuclear membrane is a double membrane inner and outer nucleus membrane each membrane consists of a lipid bilayer pores regulate entry and exit of molecules shape is maintained by nuclear lamina protein nuclear matrix similar to cytoskeleton of cytoplasm Proteins get into the nucleus by being specifically transported there importin binds to NLS and brings specific proteins to nucleus Chromatin in the nucleus made of DNA and proteins condenses to form chromosomes 23 pairs in humans Nucleolus located in the nucleus the site of rRNA synthesis and ribosomal subunit assembly 3 RNA polymerases in eukaryotes pol I rRNA 90 of cellular RNA pol II mRNA 3 pol III tRNA 7 Ribosomes particles made of rRNA and protein free ribosomes in the cytosol synthesis of intracellular proteins bound ribosomes on the outside of endoplasmic reticulum synthesis of membrane and secreted proteins
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