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Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies 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 Cell Theory 1. All organisms are composed of one or more cells. Metabolism and heredity occur within these cells. 2. Cells are the basic units of organization for all organisms. 3. Cells arise only by division of a previously existing cell.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Cells Are 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. - Small cells have more surface area per unit volume thus more effective communication.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Fig. 5.4

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. Important in harvesting light in photosynthesis, breakdown of dead organisms recycling components, cause disease, manufacture of cheese, etc. Cell wall composed of peptidoglycan  Carbohydrate matrix cross-linked by short polypeptide units.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies  Categorized by cell wall structure: - Thick, single-layered cell wall - Gram Positive  Retain a violet dye and stain purple  Susceptible to antibiotics - Multilayered cell wall - Gram Negative  Don’t retain violet dye and stain red.  Many propelled by flagellum (flagella).  Lack internal organization.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies 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)

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Nucleus 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. Restricted to proteins incorporated into nuclear structures or nuclear activities and RNA and RNA - complexes  DNA divided into chromosomes. - Chromatin

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

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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.

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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

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Vesicles Lysosomes - Membrane-bound digestive vesicles that arise from Golgi apparatus.  Contain degrading enzymes. - Break down old organelles and other structures. Microbodies – vesicles that 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 Fig. 5.19

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Ribosomes 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.

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Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Organelles With DNA Mitochondria  Very small (bacteria)  Bound by smooth outer membrane and an inner membrane folded into cristae. - Partition into matrix and intermembrane space. - Proteins for oxidative metabolism located on surface of inner membrane  Contain own DNA that synthesize proteins necessary for oxidative metabolism  They undergo replication

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Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Organelles With DNA Chloroplasts – larger then mitochondria  Manufacture their own food  Contain photosynthetic pigment chlorophyll  enclosed in a double membrane  Contain Grana - Stacked membranes lying internal to inner membrane. - Contain Thylakoids which also contain light-capturing pigments. Have their own DNA- synthesize elements in photosynthetic process Other DNA containing organelles in plants: leucoplasts and amyloplasts (leucoplasts that stores starch in roots).

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

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Cytoskeleton Network of protein fibers supports cell shape.  Individual fibers formed by polymerization. - Actin Filaments – determine shape of cells; responsible for cellular movements – contraction, crawling, pinching, and formation of cellular extensions - Microtubules – determines cell shape; moves chromosomes during cell division; cellular movement, move materials w/in the cell; in - Intermediate Filaments – stable, act as intracellular tendons to prevent excessive stretching of cells.  makeup a heterogeneous group of fibers.  Ex. Vimentin- structural stability for cells  Keratin – found in epithelial cells, hair, nails  Neurofilaments – found in nerve cells

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Cell Movement Cells exist in a gel-sol state as a result some regions of cell are rigid and some are fluid. Allows some cells to crawl via a pseudopod. Moving Material Within the Cell  Short Distances - Golgi Apparatus  Long Distances - Molecular Motors - Consists of:  Vesicle  Motor Molecule-provides energy motion  Connector Molecule-connects vesicle to motor molecule  Microtubule- rail onto which vesicle will ride Ex: Kinectin – movement is towards the cells periphery Dynein – movement is away from cells periphery

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies 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.

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Plant Cells Central Vacuole - Functions as storage center and helps increase surface-to-volume ratio.  Contains large amounts of water and other materials (sugars, ions, and pigments) Cell Walls – protect and support the plant cell  Composed of fibers of the cellulose  Present in Fungi and some protists  Primary Walls  Middle Lamella  Secondary Walls

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Endosymbiosis Theory of endosymbiosis proposes some eukaryotic organelles evolved by symbiosis.  One species of prokaryote was engulfed and lived inside another.  Ex: Mitochondria – oxidative metabolism  Chloroplasts – photosynthetic bacteria

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