04 lecture presentation
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Transcript of 04 lecture presentation
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© 2010 Pearson Education, Inc.
Lectures by Chris C. Romero, updated by Edward J. Zalisko
PowerPoint® Lectures forCampbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean DickeyCampbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey
Chapter 4Chapter 4
A Tour of the Cell
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Biology and Society: Drugs That Target Bacterial Cells
• Antibiotics were first isolated from mold in 1928.
• The widespread use of antibiotics drastically decreased deaths from bacterial infections.
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Figure 4.00
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• Most antibiotics kill bacteria while minimally harming the human host by binding to structures found only on bacterial cells.
• Some antibiotics bind to the bacterial ribosome, leaving human ribosomes unaffected.
• Other antibiotics target enzymes found only in the bacterial cells.
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THE MICROSCOPIC WORLD OF CELLS
• Organisms are either
– Single-celled, such as most prokaryotes and protists or
– Multicelled, such as plants, animals, and most fungi
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Microscopes as Windows on the World of Cells• Light microscopes can be used to explore the structures and
functions of cells.
• When scientists examine a specimen on a microscope slide
– Light passes through the specimen
– Lenses enlarge, or magnify, the image
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Light Micrograph (LM)(for viewing living cells)
Light micrograph of a protist, Paramecium
LM
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Scanning Electron Micrograph (SEM)(for viewing surface features)
Scanning electron micrograph of Paramecium
TYPES OF MICROGRAPHS
Transmission Electron Micrograph (TEM)(for viewing internal structures)
Transmission electron micrograph of Paramecium
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Figure 4.1
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Light Micrograph (LM)(for viewing living cells)
Light micrograph of a protist, Paramecium
LM
Figure 4.1a
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Scanning Electron Micrograph (SEM)(for viewing surface features)
Scanning electron micrograph of ParameciumFigure 4.1b
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Transmission Electron Micrograph (TEM)(for viewing internal structures)
Transmission electron micrograph of Paramecium
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Figure 4.1c
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• Magnification is an increase in the specimen’s apparent size.
• Resolving power is the ability of an optical instrument to show two objects as separate.
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• Cells were first described in 1665 by Robert Hooke.
• The accumulation of scientific evidence led to the cell theory.
– All living things are composed of cells.
– All cells come from other cells.
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• The electron microscope (EM) uses a beam of electrons, which results in better resolving power than the light microscope.
• Two kinds of electron microscopes reveal different parts of cells.
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• Scanning electron microscopes examine cell surfaces.
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• Transmission electron microscopes (TEM) are useful for internal details of cells.
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• The electron microscope can
– Magnify up to 100,000 times
– Distinguish between objects 0.2 nanometers apart
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Figure 4.2
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10 m
1 m
10 cm
1 cm
1 mm
100 mm
10 mm
Human height
Chicken egg
Frog eggs
Length of somenerve andmuscle cells
Un
aid
ed e
ye
Lig
ht
mic
rosc
op
e
Plant andanimal cells
Most bacteriaNucleus
Mitochondrion1 mm
100 nm
10 nm
1 nm
0.1 nm
Smallest bacteria
Viruses
Ribosomes
Proteins
Lipids
Small molecules
Atoms
Ele
ctro
n m
icro
sco
pe
Figure 4.3
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The Two Major Categories of Cells• The countless cells on earth fall into two categories:
– Prokaryotic cells — Bacteria and Archaea
– Eukaryotic cells — plants, fungi, and animals
• All cells have several basic features.
– They are all bound by a thin plasma membrane.
– All cells have DNA and ribosomes, tiny structures that build proteins.
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• Prokaryotic and eukaryotic cells have important differences.
• Prokaryotic cells are older than eukaryotic cells.
– Prokaryotes appeared about 3.5 billion years ago.
– Eukaryotes appeared about 2.1 billion years ago.
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• Prokaryotes
– Are smaller than eukaryotic cells
– Lack internal structures surrounded by membranes
– Lack a nucleus
– Have a rigid cell wall
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• Eukaryotes
– Only eukaryotic cells have organelles, membrane-bound structures that perform specific functions.
– The most important organelle is the nucleus, which houses most of a eukaryotic cell’s DNA.
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Plasma membrane(encloses cytoplasm)
Cell wall (providesRigidity)
Capsule (stickycoating)
Prokaryoticflagellum(for propulsion)
Ribosomes(synthesizeproteins)
Nucleoid(contains DNA)
Pili (attachment structures)
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Figure 4.4
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Plasma membrane(encloses cytoplasm)
Cell wall (provides rigidity)
Capsule (sticky coating)
Prokaryoticflagellum(for propulsion)
Ribosomes(synthesizeproteins)
Nucleoid(contains DNA)
Pili (attachment structures)Figure 4.4a
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Figure 4.4b
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An Overview of Eukaryotic Cells• Eukaryotic cells are fundamentally similar.
• The region between the nucleus and plasma membrane is the cytoplasm.
• The cytoplasm consists of various organelles suspended in fluid.
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• Unlike animal cells, plant cells have
– Protective cell walls
– Chloroplasts, which convert light energy to the chemical energy of food
Blast Animation: Plant Cell Overview
Blast Animation: Animal Cell Overview
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CytoskeletonRibosomes Centriole
LysosomeFlagellum
Nucleus
Plasmamembrane
Mitochondrion
Roughendoplasmic
reticulum (ER)Golgi
apparatus
Smoothendoplasmicreticulum (ER)
Idealized animal cell
Idealized plant cell
Cytoskeleton
Mitochondrion
Nucleus
Rough endoplasmicreticulum (ER)
Ribosomes
Smoothendoplasmic
reticulum (ER)
Golgi apparatus
Plasmamembrane
Channels betweencells
Not in mostplant cells
Centralvacuole
Cell wall
Chloroplast
Not in animal cells
Figure 4.5
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Cytoskeleton
Ribosomes CentrioleLysosome
Flagellum
Nucleus
Plasmamembrane
Mitochondrion
Roughendoplasmic
reticulum (ER)
Golgiapparatus
Smoothendoplasmicreticulum (ER)
Idealized animal cell
Not in mostplant cells
Figure 4.5a
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Idealized plant cell
Cytoskeleton
Mitochondrion
Nucleus
Rough endoplasmicreticulum (ER)
Ribosomes
Smoothendoplasmic
reticulum (ER)
Golgi apparatus
Plasmamembrane
Channels betweencells
CentralvacuoleCell wallChloroplast
Not inanimal cells
Figure 4.5b
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MEMBRANE STRUCTURE• The plasma membrane separates the living cell from its nonliving
surroundings.
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The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins
• The membranes of cells are composed mostly of
– Lipids
– Proteins
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• The lipids belong to a special category called phospholipids.
• Phospholipids form a two-layered membrane, the phospholipid bilayer.
Animation: Tight Junctions
Animation: Gap Junctions
Animation: Desmosomes
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(a) Phospholipid bilayer ofmembrane
(b) Fluid mosaic model ofmembrane
Outside of cell Outside of cell
Hydrophilichead
Hydrophobictail
Hydrophilicregion of
protein
Hydrophilichead
Hydrophobictail
Hydrophobicregions of
protein
Phospholipidbilayer
Phospholipid
Proteins
Cytoplasm (inside of cell)
Cytoplasm (inside of cell)
Figure 4.6
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(a) Phospholipid bilayer of membrane
Outside of cell
Hydrophilichead
Hydrophobictail
Phospholipid
Cytoplasm (inside of cell)
Figure 4.6a
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(b) Fluid mosaic model of membrane
Outside of cell
Hydrophilicregion of
protein
Hydrophilichead
Hydrophobictail
Hydrophobicregions of
protein
Phospholipidbilayer
Proteins
Cytoplasm (inside of cell)
Figure 4.6b
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• Most membranes have specific proteins embedded in the phospholipid bilayer.
• These proteins help regulate traffic across the membrane and perform other functions.
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• The plasma membrane is a fluid mosaic:
– Fluid because molecules can move freely past one another
– A mosaic because of the diversity of proteins in the membrane
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The Process of Science: What Makes a Superbug?
• Observation: Bacteria use a protein called PSM to disable human immune cells by forming holes in the plasma membrane.
• Question: Does PSM play a role in MRSA infections?
• Hypothesis: MRSA bacteria lacking the ability to produce PSM would be less deadly than normal MRSA strains.
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• Experiment: Researchers infected
– Seven mice with normal MRSA
– Eight mice with MRSA that does not produce PSM
• Results:
– All seven mice infected with normal MRSA died.
– Five of the eight mice infected with MRSA that does not produce PSM survived.
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• Conclusions:
– MRSA strains appear to use the membrane-destroying PSM protein, but
– Factors other than PSM protein contributed to the death of mice
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MRSA bacteriumproducing PSMproteins
Methicillin-resistantStaphylococcus aureus (MRSA)
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Figure 4.7-1
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MRSA bacteriumproducing PSMproteins
Methicillin-resistantStaphylococcus aureus (MRSA)
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PSM proteinsforming holein humanimmune cellplasmamembrane Plasma
membrane
PSMprotein
Pore
Figure 4.7-2
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MRSA bacteriumproducing PSMproteins
Methicillin-resistantStaphylococcus aureus (MRSA)
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PSM proteinsforming holein humanimmune cellplasmamembrane Plasma
membrane
PSMprotein
Pore
Cell bursting,losing itscontentsthroughthe pores
Figure 4.7-3
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Cell Surfaces• Plant cells have rigid cell walls surrounding the membrane.
• Plant cell walls
– Are made of cellulose
– Protect the cells
– Maintain cell shape
– Keep the cells from absorbing too much water
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• Animal cells
– Lack cell walls
– Have an extracellular matrix, which
– Helps hold cells together in tissues
– Protects and supports them
• The surfaces of most animal cells contain cell junctions, structures that connect to other cells.
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THE NUCLEUS AND RIBOSOMES:GENETIC CONTROL OF THE CELL
• The nucleus is the chief executive of the cell.
– Genes in the nucleus store information necessary to produce proteins.
– Proteins do most of the work of the cell.
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Structure and Function of the Nucleus• The nucleus is bordered by a double membrane called the
nuclear envelope.
• Pores in the envelope allow materials to move between the nucleus and cytoplasm.
• The nucleus contains a nucleolus where ribosomes are made.
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Ribosomes Chromatin Nucleolus PoreNuclearenvelope
Surface of nuclear envelope Nuclear pores
TE
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TE
M
Figure 4.8
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Ribosomes Chromatin Nucleolus PoreNuclearenvelope
Figure 4.8a
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Surface of nuclear envelope
TE
M
Figure 4.8b
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Nuclear pores
TE
M
Figure 4.8c
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• Stored in the nucleus are long DNA molecules and associated proteins that form fibers called chromatin.
• Each long chromatin fiber constitutes one chromosome.
• The number of chromosomes in a cell depends on the species.
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DNA molecule
Chromosome
Proteins
Chromatinfiber
Figure 4.9
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Ribosomes• Ribosomes are responsible for protein synthesis.
• Ribosome components are made in the nucleolus but assembled in the cytoplasm.
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Ribosome
Protein
mRNA
Figure 4.10
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• Ribosomes may assemble proteins:
– Suspended in the fluid of the cytoplasm or
– Attached to the outside of an organelle called the endoplasmic reticulum
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Ribosomes incytoplasm
Ribosomes attachedto endoplasmicreticulum
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Figure 4.11
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How DNA Directs Protein Production• DNA directs protein production by transferring its coded
information into messenger RNA (mRNA).
• Messenger RNA exits the nucleus through pores in the nuclear envelope.
• A ribosome moves along the mRNA translating the genetic message into a protein with a specific amino acid sequence.
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Synthesis ofmRNA in thenucleus
Nucleus
DNA
mRNA
Cytoplasm
Figure 4.12-1
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Synthesis ofmRNA in thenucleus
Nucleus
DNA
mRNA
Cytoplasm
mRNAMovement ofmRNA intocytoplasmvianuclear pore
Figure 4.12-2
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Synthesis ofmRNA in thenucleus
Nucleus
DNA
mRNA
Cytoplasm
mRNAMovement ofmRNA intocytoplasmvianuclear pore
Ribosome
Protein
Synthesis ofprotein in thecytoplasm
Figure 4.12-3
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THE ENDOMEMBRANE SYSTEM: MANUFACTURING AND DISTRIBUTING CELLULAR PRODUCTS• Many membranous organelles forming the endomembrane
system in a cell are interconnected either
– Directly or
– Through the transfer of membrane segments between them
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The Endoplasmic Reticulum• The endoplasmic reticulum (ER) is one of the main
manufacturing facilities in a cell.
• The ER
– Produces an enormous variety of molecules
– Is composed of smooth and rough ER
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Nuclearenvelope
Smooth ERRough ER
Ribosomes
Ribosomes
TE
M
Figure 4.13
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Nuclearenvelope
Smooth ERRough ER
Ribosomes
Figure 4.13a
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Ribosomes
TE
M
Rough ERSmooth ER
Figure 4.13b
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Rough ER
• The “rough” in the rough ER is due to ribosomes that stud the outside of the ER membrane.
• These ribosomes produce membrane proteins and secretory proteins.
• After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles.
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Proteins areoften modified inthe ER.
Secretoryproteins depart intransport vesicles.
Vesicles bud offfrom the ER.
A ribosomelinks amino acidsinto apolypeptide.
RibosomeTransportvesicle
Polypeptide
ProteinRough ER
Figure 4.14
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Smooth ER
• The smooth ER
– Lacks surface ribosomes
– Produces lipids, including steroids
– Helps liver cells detoxify circulating drugs
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The Golgi Apparatus• The Golgi apparatus
– Works in partnership with the ER
– Receives, refines, stores, and distributes chemical products of the cell
Video: Euglena
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“Receiving” side of Golgi apparatus
New vesicle forming
Transport vesiclefrom rough ER
“Receiving” sideof Golgiapparatus
Newvesicleforming
Transportvesiclefrom theGolgi
Plasmamembrane
“Shipping” sideof Golgi
apparatus
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Figure 4.15
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Transport vesiclefrom rough ER
“Receiving” side ofGolgi apparatus
Newvesicleforming
Transportvesiclefrom theGolgi
Plasmamembrane
“Shipping” side ofGolgi apparatus
Figure 4.15a
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“Receiving” side of Golgi apparatus
New vesicle forming
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Figure 4.15b
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Lysosomes• A lysosome is a sac of digestive enzymes found in animal cells.
• Enzymes in a lysosome can break down large molecules such as
– Proteins
– Polysaccharides
– Fats
– Nucleic acids
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• Lysosomes have several types of digestive functions.
– Many cells engulf nutrients in tiny cytoplasmic sacs called food vacuoles.
– These food vacuoles fuse with lysosomes, exposing food to enzymes to digest the food.
– Small molecules from digestion leave the lysosome and nourish the cell.
Animation: Lysosome Formation
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Plasma membrane Digestive enzymes
Lysosome
Digestion
Food vacuole
Lysosome
Digestion
(a) Lysosome digesting food (b) Lysosome breaking down the molecules of damaged organelles
Vesicle containingdamaged organelle
Vesicle containing twodamaged organelles
Organelle fragment
Organelle fragment
TE
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Figure 4.16
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Plasma membrane Digestive enzymes
Lysosome
Digestion
Food vacuole
(a) Lysosome digesting food
Figure 4.16a
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Lysosome
Digestion
(b) Lysosome breaking down the molecules of damaged organelles
Vesicle containing
damaged organelle
Figure 4.16b
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Vesicle containing twodamaged organelles
Organelle fragment
Organelle fragment
TE
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Figure 4.16c
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• Lysosomes can also
– Destroy harmful bacteria
– Break down damaged organelles
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Vacuoles• Vacuoles are membranous sacs that bud from the
– ER
– Golgi
– Plasma membrane
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• Contractile vacuoles of protists pump out excess water in the cell.
• Central vacuoles of plants
– Store nutrients
– Absorb water
– May contain pigments or poisons
Video: Cytoplasmic Streaming
Blast Animation: Vacuole
Video: Paramecium Vacuole
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Vacuole filling with water
Vacuole contracting
(a) Contractile vacuole in Paramecium
(b) Central vacuole in a plant cell
Central vacuoleC
olo
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d T
EM
LM
LM
Figure 4.17
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Figure 4.17a
Vacuole filling with water
Vacuole contracting
(a) Contractile vacuole in Paramecium
TE
MT
EM
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(b) Central vacuole in a plant cell
Central vacuole
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Figure 4.17b
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© 2010 Pearson Education, Inc.
• To review, the endomembrane system interconnects the
– Nuclear envelope
– ER
– Golgi
– Lysosomes
– Vacuoles
– Plasma membrane
Blast Animation : Vesicle Transport Along Microtubules
Video: Chlamydomonas
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Golgi apparatus
Transport vesicle
Plasma membrane
Secretory protein
New vesicle forming
Transport vesicle fromthe Golgi
Vacuoles store somecell products.
Lysosomes carrying digestiveenzymes can fuse with other vesicles.
Transport vesicles carry enzymesand other proteins from the roughER to the Golgi for processing.
Some productsare secretedfrom the cell.
Golgi apparatus
Rough ER
Vacuole
Lysosome
Transportvesicle
TE
M
Figure 4.18
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Golgiapparatus
Transportvesicle
Plasmamembrane
Secretoryprotein
Vacuoles store somecell products.
Lysosomes carryingdigestive enzymes canfuse with other vesicles.
Transport vesiclescarry enzymes andother proteins fromthe rough ER to theGolgi for processing.
Some productsare secretedfrom the cell.
Rough ER
Vacuole
Lysosome
Transportvesicle
Figure 4.18a
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New vesicle forming
Transport vesicle fromthe Golgi
Golgi apparatus
TE
M
Figure 4.18b
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CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION
• Cells require a constant energy supply to perform the work of life.
© 2010 Pearson Education, Inc.
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Chloroplasts• Most of the living world runs on the energy provided by
photosynthesis.
• Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar.
• Chloroplasts are the organelles that perform photosynthesis.
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• Chloroplasts have three major compartments:
– The space between the two membranes
– The stroma, a thick fluid within the chloroplast
– The space within grana, the structures that trap light energy and convert it to chemical energy
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Inner and outermembranes
Space betweenmembranes
Stroma (fluid in chloroplast) Granum
TE
M
Figure 4.19
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Inner and outermembranes
Space betweenmembranes
Stroma (fluid in chloroplast)
Granum
Figure 4.19a
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Stroma (fluid in chloroplast)
Granum
TE
M
Figure 4.19b
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Mitochondria• Mitochondria are the sites of cellular respiration, which produce
ATP from the energy of food molecules.
• Mitochondria are found in almost all eukaryotic cells.
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• An envelope of two membranes encloses the mitochondrion. These consist of
– An outer smooth membrane
– An inner membrane that has numerous infoldings called cristae
Blast Animation: Mitochondrion
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Outermembrane
Innermembrane
Cristae
Matrix
Space betweenmembranes
TE
M
Figure 4.20
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Outermembrane
Innermembrane
Cristae
Matrix
Space betweenmembranes
Figure 4.20a
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Outermembrane
Innermembrane
Cristae
Matrix
Space betweenmembranes
TE
M
Figure 4.20b
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• Mitochondria and chloroplasts contain their own DNA, which encodes some of their proteins.
• This DNA is evidence that mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past.
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THE CYTOSKELETON: CELL SHAPE AND MOVEMENT
• The cytoskeleton is a network of fibers extending throughout the cytoplasm.
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Maintaining Cell Shape• The cytoskeleton
– Provides mechanical support to the cell
– Maintains its shape
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• The cytoskeleton contains several types of fibers made from different proteins:
– Microtubules
– Are straight and hollow
– Guide the movement of organelles and chromosomes
– Intermediate filaments and microfilaments are thinner and solid.
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(a) Microtubulesin the cytoskeleton
(b) Microtubulesand movement
LM
LM
Figure 4.21
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(a) Microtubulesin the cytoskeleton
LM
Figure 4.21a
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(b) Microtubules and movement
LM
Figure 4.21b
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• The cytoskeleton is dynamic.
• Changes in the cytoskeleton contribute to the amoeboid motion of an Amoeba.
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Cilia and Flagella• Cilia and flagella aid in movement.
– Flagella propel the cell in a whiplike motion.
– Cilia move in a coordinated back-and-forth motion.
– Cilia and flagella have the same basic architecture.
Animation: Cilia and Flagella
Video: Paramecium Cilia
Video: Prokaryotic Flagella (Salmonella typhimurium)
Video: Euglena
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(a) Flagellum of a human sperm cell
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(b) Cilia on a protist
(c) Cilia lining therespiratory tract
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Figure 4.22
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(a) Flagellum of a human sperm cell
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Figure 4.22a
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(b) Cilia on a protist
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Figure 4.22b
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(c) Cilia lining the respiratory tractFigure 4.22c
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• Cilia may extend from nonmoving cells.
• On cells lining the human trachea, cilia help sweep mucus out of the lungs.
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Evolution Connection:The Evolution of Antibiotic Resistance
• Many antibiotics disrupt cellular structures of invading microorganisms.
• Introduced in the 1940s, penicillin worked well against such infections.
• But over time, bacteria that were resistant to antibiotics were favored.
• The widespread use and abuse of antibiotics continues to favor bacteria that resist antibiotics.
© 2010 Pearson Education, Inc.
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Figure 4.23
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Figure 4.23a
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Figure 4.23b
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Figure 4.UN1
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Figure 4.UN2
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Figure 4.UN3
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Figure 4.UN4
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Figure 4.UN5
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Figure 4.UN6
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Figure 4.UN7
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Figure 4.UN8
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Figure 4.UN9
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Figure 4.UN10
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Figure 4.UN11
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Prokaryotic Cells Eukaryotic Cells
• Smaller
• Simpler
• Most do not have organelles
• Found in bacteria and archaea
• Larger
• More complex
• Have organelles
• Found in protists, plants,
fungi, animals
CATEGORIES OF CELLS
Figure 4.UN12
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Outside of cell
Cytoplasm (inside of cell)
Protein
Phospholipid
Hydrophilic
Hydrophilic
Hydrophobic
Figure 4.UN13
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Light energy
Chloroplast
Mitochondrion
Chemicalenergy(food)
ATPPHOTOSYNTHESISCELLULAR
RESPIRATION
Figure 4.UN14