How Cells Are Put Together

1
How Cells Are Put Together

• Chapter 3

2
Cell Theory

• Every organism is composed of oneor more cells
• Cell is smallest unit with properties of life
• Continuity of life arises from growth and
  division of single cells

3
Cell

• Smallest unit of life
• Is highly organized for metabolism
• Senses and responds to environment
• Has potential to reproduce

4
Structure of Cells

• All start out life with
• Plasma membrane
• Region where DNA is stored
• Cytoplasm

• Two types
• Prokaryotic
• Eukaryotic

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Overview of cells
6
Common eukaryotic organelles
7
Surface-to-Volume Ratio

• Bigger cell, less surface area per unit volume
• Above a certain size, material cannot move in or
  out of cell fast enough

8
Structure of Cell Membranes

• Fluid mosaic model
• Mixed composition
• Phospholipid bilayer
• Glycolipids
• Sterols
• Proteins

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phospholipid
lipid bilayer
head
one layer of lipids
one layer of lipids
two tails
lipid bilayer
fluid
fluid
Fig. 3-6, p.42
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Phospholipids
one layer of lipids
one layer of lipids
Fig. 3-6b, p.42
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Phospholipids
lipid bilayer
fluid
fluid
Fig. 3-6c, p.42
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Lipid bilayer organization
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Membrane Proteins

• Adhesion proteins
• Communication proteins
• Receptor proteins
• Recognition proteins
• Passive transporters
• Active transporters

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Cell membranes
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Eukaryotic Cells

• Have a nucleus and other organelles
• Eukaryotic organisms
• Plants
• Animals
• Protistans
• Fungi

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Eukaryotic Cell Features

• Plasma membrane
• Nucleus
• Endoplasmic reticulum
• Golgi body
• Vesicles
• Mitochondria
• Ribosomes
• Cytoskeleton

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Table. 3-1, p.45
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The Nucleus

• Keeps the DNA molecules separated from metabolic
  machinery of cytoplasm
• Makes it easier to organize DNA and to copy it

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The endomembrane system
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Nuclear envelope
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Endomembrane System

• Related organelles where lipids are assembled and
  new polypeptide chains modified
• Sorts and ships products to various destinations
• Consists of endoplasmic reticulum, Golgi bodies,
  vesicles

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Endoplasmic Reticulum

• Starts at nuclear membrane and extends throughout
  cytoplasm
• Rough ER ribosome covered,processes proteins
• Smooth ER no ribosomes, builds lipids

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Endoplasmic Reticulum
smooth ER channel, cross-section
smooth ER
Fig. 3-9d, p.46
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Golgi Body

• Puts finishing touches on proteins and lipids
  that arrive from ER
• Packages finished material for shipment to final
  destinations
• Material arrives and leaves in vesicles

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Secretory pathway ends.
Endocytic pathway begins.
plasma membrane
budding vesicle
Golgi body
Golgi Body
Fig. 3-9e-f, p.46
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Vesicles

• Membranous sacs that move through cytoplasm
• Lysosomes
• Peroxisomes

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Mitochondria

• ATP-producing powerhouses
• Membranes form two distinct compartments
• ATP-making machinery embedded in inner
  mitochondrial membrane

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Organelle Origins

• Nucleus and ER
• Infolding of membranes formed compartments
• Mitochondria and chloroplasts
• Endosymbiosis

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Fig. 3-14, p.50
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chloroplast
flagellum
mitochondrion
nucleus
Fig. 3-14d, p.50
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Infolding Bacterial Membranes
DNA
infolding of plasma membrane
Fig. 3-15a, p.51
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Cytoskeleton

• Present in all eukaryotic cells
• Cell shape and internal organization
• Allows organelle movement within cells and, in
  some cases, cell motility