Intro to the Cell Ch. 6

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Intro to the Cell Ch. 6

• Lecture Objectives1. Cell History
• 2.Prokaryotic vs. Eukaryotic Cells
• 3. Cellular Organelles
• 4. Endosymbiont Theory

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History of the Cell

• 2. Van Leuwenhooke
• a. First to identify cells as living structures

• 1. Robert Hooke
• a. first to name cells

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The Cell Theory Schleiden Schwann

• 1. All organisms are made of cells
• 2. The cell is the simplest collection of matter
  that can be alive
• 3. Cell structure is correlated to cellular
  function
• 4. All cells are related by their descent from
  earlier cells

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Comparing Prokaryotic Eukaryotic Cells

• Basic features of ALL cells
• 1. Plasma membrane
• 2. Semifluid substance called cytosol within
  cytoplasm (area between PM and nucleus)
• 3. Genetic Material
• 4. Ribosomes

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Figure 6.8c
Parent cell
1 µm
10 µm
Cell wall
Buds
Cell
Vacuole
Animal Cells
Fungal Cells
Nucleus
5 µm
Nucleolus
Nucleus
Yeast cells budding (colorized SEM)
Human cells from lining of uterus (colorized TEM)
Mitochondrion
A single yeast cell (colorized TEM)
Cell
Flagella
1 µm
5 µm
8 µm
Cell wall
Chloroplast
Nucleus
Unicellular Eukaryotes
Mitochondrion
Nucleolus
Plant Cells
Nucleus
Vacuole
Nucleolus
Chlamydomonas (colorized SEM)
Chloroplast
Cells from duckweed (colorized TEM)
Cell wall
Chlamydomonas (colorized TEM)
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• Prokaryotic cells are characterized by having
  ONLY
• 1. Cell Walls
• 2. Free-floating circular DNA
• 3. No membrane-bound organelles

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Fimbriae
Nucleoid
Ribosomes
Plasmamembrane
Bacterialchromosome
Cell wall
Capsule
0.5 ?m
Flagella
(b)
(a)
A typicalrod-shapedbacterium
A thin sectionthrough thebacterium
Bacilluscoagulans (TEM)
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Eukaryotic CellsTypical Animal cell
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The Eukaryotic Cell Membrane Bound Organelles
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• 1. Plasma membrane
• a. selectively permeable
• 2. Nucleus
• a. surrounded by 2 membranes interrupted by
  pores
• b. stores DNA

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Figure 6.9
Nucleus
1 µm
Nucleus
Nucleolus
Chromatin
Nuclear envelope
Inner membrane
Outer membrane
Nuclear pore
Rough ER
Pore complex
Surface of nuclear envelope (TEM)
Ribosome
Close-up of nuclear envelope
Chromatin
0.25 µm
0.5 µm
Pore complexes (TEM)
Nuclear lamina (TEM)
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• 3. Endoplasmic Reticulum (ER)
• a. continuous with the nuclear envelope
• b. two distinct regions of ER
• Smooth ER
• synthesizes lipids
• metabolizes carbohydrates
• detoxifies drugs and poisons
• Rough ER
• manufactures proteins
• (exported from cell)

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Figure 6.11
Smooth ER
Rough ER
Nuclear envelope
Smooth ER
Rough ER
ER lumen
Cisternae
Transitional ER
Ribosomes
Transport vesicle
0.20 µm
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• 4. Golgi apparatus
• a. flattened membranous sacs
• b. cis and trans sides
• c. Functions
• - Modifies products of the ER
• - Manufactures certain macromolecules
• - Sorts packages materials ? transport
  vesicle

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Figure 6.12
Golgi apparatus
cis face (receiving side of Golgi apparatus)
0.1 µm
Cisternae
trans face (shipping side of Golgi apparatus)
TEM of Golgi apparatus
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Nucleus
Rough ER
Smooth ER
cis Golgi
Plasmamembrane
trans Golgi
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• 5. Lysosomes a. Membranous sac of digestive
  enzymes
• b. Function
• - autophagy
• - recycling
• - digestion

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Figure 6.13
Vesicle containing two damaged organelles
1 µm
Nucleus
1 µm
Mitochondrion fragment
Peroxisome fragment
Lysosome
Digestive enzymes
Lysosome
Lysosome
Peroxisome
Plasma membrane
Digestion
Food vacuole
Digestion
Mitochondrion
Vesicle
(a)
(b)
Phagocytosis lysosome digesting food
Autophagy lysosome breaking down damaged
organelles
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• 6. Vacuoles
• a. diverse maintenance compartments
• (derived from ER and Golgi apparatus)
• b. examples
• - food vacuoles
• - contractile vacuoles
• - central vacuoles

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Figure 6.14
Central vacuole
Cytosol
Central vacuole
Nucleus
Cell wall
Chloroplast
5 µm
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Endomembrane System regulates protein traffic and
performs metabolic functions in the cell

• Components
• Nuclear envelope
• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
• Vacuoles
• Plasma membrane
• These components are either continuous or
  connected via transfer by vesicles

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• 7. Mitochondria
• a. Structure-
• - surrounded by a double membrane - DNA and
  ribosomes - number varies by cell type
• b. Function
• - cellular respiration

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Figure 6.17
Mitochondrion
10 µm
Mitochondria
Intermembrane space
Outer membrane
DNA
Inner membrane
Free ribosomes in the mitochondrial matrix
Mitochondrial DNA
Cristae
Nuclear DNA
Matrix
0.1 µm
(a)
Diagram and TEM of mitochondrion
Network of mitochondria in Euglena (LM)
(b)
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• 8. Chloroplast
• a. Structure
• - contains green pigment (chlorophyll) -
  number varies by cell type
• b. Function - photosynthesis

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Figure 6.18
Chloroplast
50 µm
Ribosomes
Stroma
Inner and outer membranes
Granum
Chloroplasts (red)
DNA
1 µm
Thylakoid
Intermembrane space
Diagram and TEM of chloroplast
(a)
Chloroplasts in an algal cell
(b)
(b)
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• Cytoskeleton
• a. network of fibers extending throughout the
  cytoplasm
• b. organizes the cells structures and
  activities, anchors organelles
• Technically not an organelle.

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• The Endosymbiont theory
• 1. An early ancestor of eukaryotic cells engulfed
  a non-photosynthetic prokaryotic cell, which
  formed an endosymbiont relationship with its host
• 2. The host cell and endosymbiont merged into a
  single organism, a eukaryotic cell with a
  mitochondrion
• 3. At least one of these cells may have taken up
  a photosynthetic prokaryote, becoming the
  ancestor of cells that contain chloroplasts

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Nucleus
Endoplasmicreticulum
Engulfing of oxygen-using nonphotosyntheticproka
ryote, whichbecomes a mitochondrion
Nuclear envelope
Ancestor ofeukaryotic cells(host cell)
Mitochondrion
Engulfing ofphotosyntheticprokaryote
At leastone cell
Chloroplast
Nonphotosyntheticeukaryote
Mitochondrion
Photosynthetic eukaryote