Lecture 9 & 10 Notes - BIO 202 Notes Lecture 9 Cell...

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BIO 202 Notes Lecture 9: Cell structure, organelles 1; Lecture 10: Organelles 2 Chapter 6: A Tour of the Cell 1. 6.3 The Eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes 1. The Nucleus: Genetic Library of the Cell 1. The nucleus contains most of the genes in the eukaryotic cell 2. Nuclear envelope: encloses the nucleus, separating its contents from the cytoplasm 1. Double membrane 1. Each a lipid bilayer + proteins 2. Perforated by pores 1. Inner and outer membranes of envelope are continuous 2. Pore complex: intricate protein structure which lines each pore and regulates the entry and exit of certain large macromolecules and particles 3. Nuclear side of envelope is lined by the nuclear lamina 1. Netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope 2. Does not line pores 3. Nuclear matrix: framework of fibers extending throughout the nuclear interior 4. Inside the nucleus 1. Chromosomes: discrete units of DNA which carry genetic information 1. Made up of chromatin 1. Complex of proteins and DNA 2. Nucleolus: mass of densely stained granules and fibers adjoining part of the chromatin 1. Synthesizes ribosomal RNA (rRNA) 2. Where proteins imported from the cytoplasm are assembled with rRNA into large and small ribosomal subunits 1. Exit the nucleus through the nuclear pores to the cytoplasm 2. A large and small subunit can assemble into a ribosome 5. The nucleus directs protein synthesis 1. Messenger RNA (mRNA) are synthesized according to instructions provided by the DNA 2. The mRNA is transported to the cytoplasm through the nuclear pores 3. When the mRNA reaches the cytoplasm, ribosomes translate the mRNA’s genetic message into the primary structure of a polypeptide 2. Ribosomes: Protein Factories in the Cell 1. Ribosomes: organelles that carry out protein synthesis 1. Made of ribosomal RNA and protein 2. Ribosome function depends on placement 1. Free ribosomes 1. Suspended in the cytosol 2. Mostly make proteins that function within the cytosol 2. Bound ribosomes 1. Attached to the outside of the endoplasmic reticulum or nuclear envelope 2. Mostly make proteins destined for 1. insertion into membranes 2. packaging within certain organelles (i.e. lysosomes) 3. secretion (export from the cell)
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BIO 202 Notes 3. Free and bound ribosomes are structurally identical and can alternate between roles 1. Cell adjusts relative numbers as metabolic changes alter the types of proteins that must be synthesized 2. 6.4 The endomembrane system regulates protein traffic and performs metabolic functions in the cell 1. Endomembrane system: system of different membranes of the eukaryotic cell 1. Carries out a variety of tasks in the cell 1. Synthesis of proteins 2.
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