Cell Structure Chapter 4 Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Phospholipid bilayer with embedded proteins. Transport Proteins Cells Plasma Membrane - Encloses cell and separates contents from surroundings. Phospholipid bilayer with embedded proteins. Transport Proteins Receptor Proteins Nucleus of eukaryotes contains DNA. Cytoplasm - Semi-fluid matrix filling cell interior. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

All organisms are composed of one or more cells. Cell Theory All organisms are composed of one or more cells. Metabolism and heredity occur within these cells. Cells are the basic units of organization for all organisms. Cells arise only by division of a previously existing cells. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Cells are small: Microscopes help us see cells Resolution - Minimum distance two points can be apart and still be distinguished as separate points. Must be at least 100 micrometers for the human eye to detect difference. Light Microscope - Utilize two magnifying lenses. Compound Microscopes - Magnify in multiple stages using several lenses. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Cells Are Small Electron Microscopes use beams of electrons (shorter wavelengths) rather than light to see images only 0.2 nanometers! Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Transmission Electron Microscope Electrons used to visualize specimens are transmitted through the material. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Scanning Electron Microscope Electrons are beamed onto the surface from a probe passed rapidly back and forth. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Cell membrane plays a key role in controlling cell function (the door) Why are Cells Small? Advantage of small cell size is explained by surface area-to-volume ratio. As a cell’s size increases, its volume increases much more rapidly than surface area. Cell membrane plays a key role in controlling cell function (the door) Small cells have more surface area per unit volume (larger door) Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

As a cell’s size increases, its surface area: volume ratio decreases Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Prokaryotic Cells Bacterial cells are small, consisting of cytoplasm surrounded by a plasma membrane enclosed within a rigid cell wall. Categorized by cell wall structure: Gram Positive - Thick, single-layered cell wall. Gram Negative - Multilayered cell wall. Antibiotic susceptibility depends on cell wall structure Many propelled by flagellum (flagella). Simple organization Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Vesicles - Storage and Transport Nucleus - Chromosomes (DNA) Eukaryotic Cells Interior of eukaryotic cells contain numerous membrane-bound structures (organelles) that close off compartments to allow multiple simultaneous biochemical processes. Vesicles - Storage and Transport Nucleus - Chromosomes (DNA) Cytoskeleton - Internal Structure Central Vacuole - Storage (Plants Only) Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Nucleus is the repository of genetic information. Nuclear envelope bound by two phospholipid bilayer membranes. Nuclear pores filled with proteins permit passage of material in and out of the cell. DNA divided into chromosomes (rather than a single circular piece of DNA) Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Nucleus As a cell prepares to divide, DNA coils around histones (packaging proteins) into a highly condensed form, a nucleosome. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Endoplasmic Reticulum Internal membrane composed of phospholipid bilayer and embedded proteins. Weaves through cell, creating series of channels between its folds. Rough ER - Surface regions covered with ribosomes. Synthesizes proteins for export. Smooth ER - Membrane has few embedded ribosomes, and is embedded with enzymes for lipid synthesis. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Cis face - Receiving end Trans face - Discharging end Golgi Apparatus Collection of interconnected flattened stacks of membranes (Golgi bodies). Function in collection, packaging, and distribution of molecules synthesized in one place, and utilized in another place within the cell. Cis face - Receiving end Trans face - Discharging end Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Contain degrading enzymes. Vesicles Lysosomes - Membrane-bound digestive vesicles that arise from Golgi apparatus. Contain degrading enzymes. Break down old organelles and other structures. Microbodies - Bear enzymes. Glyoxysome - Convert fat into carbohydrates (Plants). Peroxisome - Catalyze removal of electrons and associated hydrogen atoms. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Ribosomes are site of protein synthesis. Made up of rRNA bound within complex of several dozen different proteins. Composed of two subunits. Join to form functional ribosome only when they attach to messenger RNA. Assembled in nucleolus within the nucleus. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Partition into matrix and intermembrane space. Contain own DNA. Organelles With DNA Mitochondria Bound by smooth outer membrane and an inner membrane folded into cristae. Partition into matrix and intermembrane space. Contain own DNA. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Grana - Stacked membranes internal of inner membrane. Organelles With DNA Chloroplasts Contain photosynthetic pigment chlorophyll that gives most plants their green color. Double membrane Grana - Stacked membranes internal of inner membrane. Contain Thylakoids which also contain light-capturing pigments. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Chloroplast Structure Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Help assemble microtubules. Some appear to contain DNA. Organelles With DNA Centrioles - Barrel-shaped organelles usually located near nuclear membrane. Help assemble microtubules. Some appear to contain DNA. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Network of protein fibers supports cell shape. Cytoskeleton Network of protein fibers supports cell shape. Individual fibers formed by polymerization. Actin Filaments Microtubules Intermediate Filaments Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Some cells crawl via a pseudopod. Moving Material Within the Cell Cell Movement Some cells crawl via a pseudopod. Moving Material Within the Cell Short Distances - Golgi Apparatus Long Distances - Molecular Motors Vesicle Motor Molecule Connector Molecule Microtubule Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Derived from a basal body. Cell Movement Many eukaryotic contain flagellum consisting of a circle of nine microtubule pairs surrounding two central mictotubules. Derived from a basal body. Cilia - Short cellular projections often organized in rows. Organization similar to flagella. Carry out multitude of functions. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Plant Cells Central Vacuole - Functions as storage center and helps increase surface-to-volume ratio. Cell Walls Primary Walls Middle Lamella Secondary Walls Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

One species of prokaryote was engulfed and lived inside another. Endosymbiosis Theory of endosymbiosis proposes some eukaryotic organelles evolved by symbiosis. One species of prokaryote was engulfed and lived inside another. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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Copyright © McGraw-Hill Companies Permission required for reproduction or display Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies