1. Cell Structure Chapter 4
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2. 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.
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3. 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.
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4. 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.
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5. Cells Are Small
Electron Microscopes use beams of electrons (shorter wavelengths) rather than light to see images only 0.2 nanometers!
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6. Transmission Electron Microscope
Electrons used to visualize specimens are transmitted through the material.
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7. Scanning Electron Microscope
Electrons are beamed onto the surface from a probe passed rapidly back and forth.
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8. 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)
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9. As a cell’s size increases, its surface area: volume ratio decreases
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10. 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
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11. Raven - Johnson - Biology: 6th Ed
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12. 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)
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14. Raven - Johnson - Biology: 6th Ed
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15. 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)
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17. Nucleus
As a cell prepares to divide, DNA coils around histones (packaging proteins) into a highly condensed form, a nucleosome.
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18. 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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20. 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
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22. 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.
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23. 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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24. 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.
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26. 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.
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27. Chloroplast Structure
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28. 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.
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29. 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
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31. 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
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32. 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.
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34. Plant Cells
Central Vacuole - Functions as storage center and helps increase surface-to-volume ratio.
Cell Walls
Primary Walls
Middle Lamella
Secondary Walls
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35. 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.
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