Cell Structure all life is based on cells Copyright © McGraw-Hill

Cell Structure all life is based on cells Copyright © McGraw-Hill
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all life is based on cells
Outline Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Cell Structure Organelles Cell Movement Endosymbiosis all life is based on 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. all life is based on 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 cell. all life is based on cells

Cells Are Small 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. all life is based on cells

LIGHT MICROSCOPE HIGHEST MAGNIFICATION IS ABOUT 1000 TIMES HIGHEST RESOLVING POWER IS ABOUT 0.2 MICROMETERS. RELATIVELY CHEAP AND EASY TO USE CONDENSER LENS FOCUSES LIGHT ON A SPECIMEN. all life is based on cells

Cells Are Small Electron Microscopes use beams of electrons (shorter wavelengths) rather than light. Transmission - Electrons used to visualize specimens are transmitted through the material. Scanning - Electrons are beamed onto the surface from a probe passed rapidly back and forth. all life is based on cells

ELECTRON MICROSCOPE USES MAGNETS RATHER THAN LENS. HAVE 400 TIMES THE RESOLVING POWER OF A LIGHT MICROSCOPE. TO USE THE SPECIMEN HAS TO BE KILLED AND ARTIFACTS MAY BE PRODUCED EXPENSIVE TO USE all life is based on cells

Fig. 6-3 TECHNIQUE RESULTS (a) Brightfield (unstained specimen) 50 µm (b) Brightfield (stained specimen) (c) Phase-contrast (d) Differential-interference- contrast (Nomarski) (e) Fluorescence Figure 6.3a-d Light microscopy 50 µm (f) Confocal all life is based on cells 50 µm

Fig. 6-3ab TECHNIQUE RESULTS (a) Brightfield (unstained specimen) 50 µm (b) Brightfield (stained specimen) Figure 6.3 Light microscopy all life is based on cells

Fig. 6-3cd TECHNIQUE RESULTS (c) Phase-contrast (d) Differential-interference- contrast (Nomarski) Figure 6.3 Light microscopy all life is based on cells

Fig. 6-3e TECHNIQUE RESULTS (e) Fluorescence Figure 6.3 Light microscopy 50 µm all life is based on cells

Fig. 6-3f TECHNIQUE RESULTS (f) Confocal Figure 6.3 Light microscopy 50 µm all life is based on cells

Fig. 6-4 TECHNIQUE RESULTS 1 µm (a) Scanning electron microscopy (SEM) Cilia (b) Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium 1 µm Figure 6.4 Electron microscopy all life is based on cells

CELL SIZES MICROMETER=1 MILLIONTH OF A METER NANOMETER=1 BILLIONTH OF A METER all life is based on cells

CELL SIZES II MOST CELLS ARE MICROMETERS IN DIAMETER. SOME EUKARYOTIC CELLS ARE UP TO 100 MICROMETERS IN DIAMETER. MOST BACTERIA ARE 1-10 MICROMETER IN DIAMETER. all life is based on cells

CELL SIZES III MOLECULES- 1 NANOMETER MEMBRANE THICKNESS-10 NANOMETERS VIRUSES- 100 NANOMETERS ORGANELLES- UP TO 10 MICROMETERS all life is based on cells

CELL SIZES IV THE UPPER LIMITS OF CELL SIZE ARE IMPOSED BY THE SURFACE AREA TO VOLUME RATIO. AS A CELL INCREASES IN SIZE, ITS VOLUME GROWS PROPORTIONATELY MORE THAN ITS SURFACE AREA. SURFACE AREA SQUARES WHILE VOLUME CUBES. all life is based on cells

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. all life is based on cells

Surface area increases while total volume remains constant
Fig. 6-8 Surface area increases while total volume remains constant 5 1 1 Total surface area [Sum of the surface areas (height  width) of all boxes sides  number of boxes] 6 150 750 Total volume [height  width  length  number of boxes] Figure 6.8 Geometric relationships between surface area and volume 1 125 125 Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 6 1.2 6 all life is based on cells

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. Many propelled by flagellum (flagella). Lack internal organization. all life is based on cells

Fig. 6-6 Fimbriae Nucleoid Ribosomes Plasma membrane Bacterial chromosome Cell wall Capsule 0.5 µm Flagella (a) A typical rod-shaped bacterium (b) A thin section through the bacterium Bacillus coagulans (TEM) Figure 6.6 A prokaryotic cell all life is based on cells

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) all life is based on cells

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. DNA divided into chromosomes. Chromatin all life is based on cells

Nucleus As a cell prepares to divide, DNA coils around histones (packaging proteins) into a highly condensed form, a nucleosome. all life is based on cells

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. all life is based on cells

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 all life is based on cells

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. all life is based on cells

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. all life is based on cells

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. all life is based on cells

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. all life is based on cells

Chloroplast Structure

Organelles With DNA Centrioles - Barrel-shaped organelles usually located near nuclear membrane. Help assemble microtubules. Some appear to contain DNA. all life is based on cells

Cytoskeleton Network of protein fibers supports cell shape. Individual fibers formed by polymerization. Actin Filaments Microtubules Intermediate Filaments all life is based on cells

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 all life is based on cells

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. all life is based on cells

Plant Cells Central Vacuole - Functions as storage center and helps increase surface-to-volume ratio. Cell Walls Primary Walls Middle Lamella Secondary Walls all life is based on cells

Endosymbiosis Theory of endosymbiosis proposes some eukaryotic organelles evolved by symbiosis. One species of prokaryote was engulfed and lived inside another. all life is based on cells

Review Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Cell Structure Organelles Cell Movement Endosymbiosis all life is based on cells

Cell Structure all life is based on cells Copyright © McGraw-Hill

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Cell Structure all life is based on cells Copyright © McGraw-Hill

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Presentation on theme: "Cell Structure all life is based on cells Copyright © McGraw-Hill"— Presentation transcript:

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