chap 6 lecture part 1 with audio
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 6Chapter 6
A Tour of the Cell
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Overview: The Importance of Cells
• All organisms are made of cells
• The cell is the simplest collection of matter that can live
• Cell structure is correlated to cellular function
• All cells are related by their descent from earlier cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
How do the different parts of a cell function separately and together?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 6.1: To study cells, biologists use microscopes and the tools of biochemistry
• Though usually too small to be seen by the unaided eye, cells can be complex
• Two important parameters of microscopy
– Magnification- ratio of object image to real size
– Resolution- clarity of the image
• Light microscopes pass light through specimen and then through glass lenses
– Resolution of 200 nanometers, i.e. small bacteria
– Magnification 1000 times the actual size
LE 6-2
Measurements1 centimeter (cm) = 10–2 meter (m) = 0.4 inch1 millimeter (mm) = 10–3 m1 micrometer (µm) = 10–3 mm = 10–6 m1 nanometer (nm) = 10–3 µm = 10–9 m
10 m
1 mHuman height
Length of somenerve andmuscle cells
Chicken egg
0.1 m
1 cm
Frog egg1 mm
100 µm
Most plant andanimal cells
10 µmNucleus
1 µm
Most bacteria
Mitochondrion
Smallest bacteria
Viruses100 nm
10 nmRibosomes
Proteins
Lipids
1 nmSmall molecules
Atoms0.1 nmU
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Light Microscope
Brightfield(unstained)
Brightfield(stained)
Phase-contrast
50 µm
Confocal
Differential-Interference-Contrast(Nomarski)
Fluorescence
50 µm
50 µm
LE 6-41 µm
1 µm
Cilia
Longitudinalsection ofcilium
Cross sectionof cilium
Used to study subcellular structures
Scanning electron microscopes (SEMs) focus a beam of electrons onto the surface of a specimen, providing images that look 3D
Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen
TEMs are used mainly to study the internal ultrastructure of cells
Electron Microscopes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Isolating Organelles by Cell Fractionation
• Cell fractionation takes cells apart and separates the major organelles from one another
• Ultracentrifuges fractionate cells into their component parts
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Isolating Organelles by Cell Fractionation
Homogenization
HomogenateTissuecells
Differential centrifugation
Pellet rich innuclei andcellular debris
Pellet rich in mitochondria (and chloroplasts if cellsare from a plant)
Pellet rich in “microsomes”(pieces of plasma membranesand cells’ internal membranes)
Pellet rich in ribosomes
150,000 g3 hr
80,000 g60 min
20,000 g20 min
1000 g(1000 times the force of gravity)10 min
Supernatant pouredinto next tube
Cell fractionation enables scientists to determine the functions of organelles
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept Check
• How do the stains used for light microscopy compare with those used for electron microscopy?
• Which type of microscope would you use to study…
• Changes in the shape of a white blood cell?
• Surface texture of hair?
• Detailed structure of an organelle?
Prokaryotic vs. Eukaryotic Cells
Nucleus- no yes
Membrane
Bound organelles no yes
Plasma membrane yes yes
Cytosol yes yes
Chromosomes yes yes
Ribosomes yes yes
Domain Bacteria, Archea protist ,fungi, plant
animal
The two types of cells
LE 6-6
A typicalrod-shapedbacterium
A thin section through thebacterium Bacilluscoagulans (TEM)
0.5 µm
Pili
Nucleoid
Ribosomes
Plasmamembrane
Cell wall
Capsule
Flagella
Bacterialchromosome
LE 6-7
Total surface area(height x width xnumber of sides xnumber of boxes)
6
125 125
150 750
1
11
5
1.2 66
Total volume(height x width x lengthX number of boxes)
Surface-to-volumeratio(surface area volume)
Surface area increases whileTotal volume remains constant
Larger organisms do not have larger cells- simple more cells
Hydrophilicregion
Hydrophobicregion
Carbohydrate side chain
Structure of the plasma membrane
Hydrophilicregion
Phospholipid Proteins
Outside of cell
Inside of cell 0.1 µm
TEM of a plasma membrane
Function - selective barrier that allows sufficient passage of oxygen, nutrients, and waste
Structure - double layer of phospholipids
The boundary of every cell – Plasma membrane
Flagellum
Centrosome
CYTOSKELETON
Microfilaments
Intermediate filaments
Microtubules
Peroxisome
Microvilli
ENDOPLASMIC RETICULUM (ER
Rough ER Smooth ER
MitochondrionLysosome
Golgi apparatus
Ribosomes:
Plasma membrane
Nuclear envelope
NUCLEUS
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
Nucleolus
Chromatin
A Panoramic View of the Eukaryotic CellA Panoramic View of the Eukaryotic Cell
LE 6-9b
Roughendoplasmicreticulum
In plant cells but not animal cells:
Chloroplasts
Central vacuole and tonoplast
Cell wall
Plasmodesmata
Smoothendoplasmicreticulum
Ribosomes(small brown dots)
Central vacuole
Microfilaments
IntermediatefilamentsMicrotubules
CYTOSKELETON
Chloroplast
Plasmodesmata
Wall of adjacent cell
Cell wall
Nuclearenvelope
Nucleolus
Chromatin
NUCLEUS
Centrosome
Golgiapparatus
Mitochondrion
Peroxisome
Plasmamembrane
A Panoramic View of the Eukaryotic CellA Panoramic View of the Eukaryotic CellA Panoramic View of the Eukaryotic CellA Panoramic View of the Eukaryotic Cell
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• A eukaryotic cell has internal membranes that partition the cell into organelles
– Nucleus – contains most of the DNA
– Ribosomes – use info from DNA to make proteins
– Endomembrane system – variety of tasks, protein synthesis, transport, lipid metabolism, detoxification
– Lysosyme – digest macromolecules
– Vacuoles
– Mitochondria – cellular respiration
– Chloroplasts - photosynthesis
Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions