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Chapter 4 Plasma membrane, nucleus and ribosomes What to Know • The structure and function of the plasma membrane, nucleus and ribosomes. Figure 4.5 Outside of cell (a) TEM of a plasma membrane Plasma Membrane Inside of cell 0.1 m Carbohydrate side chains Hydrophilic region Hydrophobic region Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane Concept 4.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes • The nucleus contains most of the DNA in a eukaryotic cell. • Ribosomes use the information from the DNA to make proteins. © 2014 Pearson Education, Inc. Nucleus Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Rough ER Pore complex Ribosome Close-up of nuclear envelope Chromatin Ribosomes: Protein Factories • Ribosomes are complexes of ribosomal RNA and protein. • Ribosomes carry out protein synthesis in two locations – In the cytosol (free ribosomes) – On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes) © 2014 Pearson Education, Inc. Figure 4.9 0.25 m Ribosomes ER Free ribosomes in cytosol Endoplasmic reticulum (ER) Ribosomes bound to ER Large subunit Small subunit TEM showing ER and ribosomes Diagram of a ribosome Figure 4.7b Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum NUCLEUS Ribosomes Central vacuole Golgi apparatus Microfilaments CYTOIntermediate SKELETON filaments Microtubules Mitochondrion Peroxisome Plasma membrane Cell wall Wall of adjacent cell Chloroplast Plasmodesmata You should be familiar with the parts of a cell. 1 m Nuclear envelope: Inner membrane Outer membrane back