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Download Ch 3 - Cell Structure and Genetic Control
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Ch 4 – A Tour of the Cell The cell is the basic unit of structure and function in the body. Prokaryote v. Eukaryote • Are smaller than eukaryotic cells • Lack internal structures surrounded by membranes • Lack a nucleus There are three principal parts: – plasma membrane (plasmalemma) – cytoplasm and organelles – nucleus.. Prokaryotic flagella Nucleoid region (DNA) Plasma membrane Cell wall Capsule Pili Ribosomes Ribosomes Cytoskeleton Centriole Lysosome Flagellum Not in most plant cells Plasma membrane Nucleus Mitochondrion Rough endoplasmic reticulum (ER) Golgi apparatus Smooth endoplasmic reticulum (ER) Not in animal cells Cytoskeleton Mitochondrion Central vacuole Nucleus Cell wall Rough endoplamsic reticulum (ER) Chloroplast Ribosomes Plasma membrane Smooth endoplasmic reticulum (ER) Plasmodesmata Golgi apparatus • The plasma membrane is composed of a phospholipid bilayer with embedded proteins. Hydrophilic region of protein Phospholipid bilayer Hydrophobic region of protein (b) Fluid mosaic model of membrane • The functions of plasma membrane include: – selectively permeable and surrounds the cellular contents. – regulates the passage of materials into and out of the cell. – participates in intercellular communications.. Transport of materials across the plasma membrane • In general: – large macromolecules cannot cross the membrane – charged molecules cannot cross the membrane – small, non-charged molecules can cross – water can cross.. • The cytoplasm (cytosol) is the gelatinous material inside the cell membrane but outside the nucleus. • The cytoplasm contains organelles which are sub-cellular structures that perform discrete functions. True organelles are bounded by a phospholipid membrane.. • The nucleus is a double-membrane organelle containing the nucleic acids (DNA) and at least one nucleolus (contains ribosomal RNA). • This organelle stores the genetic information and contains the blueprints for almost all protein syntheses. – DNA RNA protein.. Ribosomes Chromatic Nuclear envelope Nucleolus Pore Organelles of a Typical Cell Ribosome Endoplasmic Reticulum (ER) *Rough Production of proteins – located attached to ER or free-floating Passageway for materials Produces proteins & processes molecules for secretion Produces lipids & detoxifies drugs *Smooth & stores Ca++ Golgi Apparatus Packages material for export & processes macromolecules Vacuole & vesicle Storage.. Lysosome Contains digestive enzymes. Each contains one specific enzyme. Chloroplasts Carries out photosynthesis: 6CO2 + 6H2O Mitochondria Aerobic cellular respiration: C6H12O6 + 6O2 Cilia, flagella, microvilli C6H12O6 + 6O2 6CO2 + 6H2O +ATP Surface projections – increase surface area & produce movement.. CELL-CELL INTERACTIONS • Plant cells are encased by cell walls – These provide support for the plant cells Walls of two adjacent plant cells Vacuole Plasmodesmata (channels between cells) • Animal cells lack cell walls – They secrete a sticky covering called the extracellular matrix – This layer helps hold cells together • Animal cells connect by various types of junctions – Tight junctions – Adhering junctions – Communicating junctions Extracellular matrix (a) Tight junctions (b) Anchoring junctions (c) Communicating junctions Plasma membranes of adjacent cells Extracellular matrix
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