chapter 4: tour of the eukaryotic cell © 2012 pearson education, inc
TRANSCRIPT
Chapter 4:
Tour of the Eukaryotic Cell
© 2012 Pearson Education, Inc.
Table 4.22
Eukaryotic cells have membrane-bound nucleus and organelles
Nucleus: membrane-bound compartment for DNA
Organelles: cell structures each wrapped with own membrane
Eukaryotes include: protists, plants, animals, fungi
Animal vs plants:
– Lysosomes, centrioles, cilia and flagella are not found in plant cells.
– Plant but not animal cells have
– a rigid cell wall,
– chloroplasts, and
– a central vacuole
– Plasmodesmata (cell to cell passageways)
Why So Many Organelles?
Each organelle has specific function
– Increases efficiency of cell function
– Allows for opposing cellular functions to occur in different compartments
– Allows eukaryotic cells to be larger!!
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Smoothendoplasmicreticulum
Roughendoplasmicreticulum
NUCLEUS:NuclearenvelopeChromatinNucleolus
Ribosomes
Golgiapparatus
Mitochondrion
Plasma membrane
Peroxisome
CYTOSKELETON:Microtubule
Intermediatefilament
Microfilament
Lysosome
Centriole
NOT IN MOSTPLANT CELLS:
In animal cells but not plant cells: LysosomesCentriolesFlagella (in some plant sperm)
Figure 4.4B
NUCLEUS:Nuclear envelopeChromatinNucleolus
Golgiapparatus
Roughendoplasmicreticulum
Ribosomes
Peroxisome
Central vacuole
NOT IN ANIMAL CELLS:
ChloroplastCell wall
Plasmodesma
Mitochondrion
Plasma membrane
Cell wall ofadjacent cell
Smoothendoplasmicreticulum
CYTOSKELETON:MicrotubuleIntermediatefilamentMicrofilament
In plant cells but not animal cells: ChloroplastsCentral vacuoleCell wallPlasmodesmata
Cell structures support cell functions Cell reproduction, carry out genetic instructions, make new
proteins
– Nucleus, nucleolus, ribosomes, centrioles
Synthesize and distribute new molecules, degrade and remove wastes
– Endomembrane system
– Smooth and rough ER, golgi, lysosomes, vacuoles, transport vesicles
Energy processing
– Mitochondria and chloroplasts
Cell shape/support, movement, communication to outside world
– Plasma membrane, cytoskeleton, extracellular matrix (animals), cell wall (plants)
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Cells Must Make New Cells and Proteins
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Reproduction, control center, protein synthesis
Nucleus - houses DNA
– DNA + packing proteins = chromatin
– nuclear envelope surrounds nucleus
– Double membrane
Ribosomes built from rRNA and protein
– Reads mRNA copy of gene and directs synthesis of protein
– Free ribosomes - in cytoplasm - produce proteins that work in cytoplasm
– Bound ribosomes - associated with rough ER - produce proteins that work within endomembrane system or outside cell
Nucleolus (nucleoli) - site of rRNA and ribosome production
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Two membranesof nuclear envelope
Nucleus
Chromatin
Nucleolus
Pore
Endoplasmicreticulum
Ribosomes
Nucleus - houses DNA
–DNA + packing proteins = chromatin
–nuclear envelope surrounds nucleus
–Double membrane
Nucleolus (nucleoli) - site of ribosome production
Ribosomes ERCytoplasm
Endoplasmicreticulum (ER)
Free ribosomes
Boundribosomes
Diagram ofa ribosome
ProteinmRNA
Colorized TEM showingER and ribosomes
Ribosomes built from rRNA and protein
–Reads mRNA copy of gene and directs synthesis of protein
–Free ribosomes - in cytoplasm - produce proteins that work in cytoplasm
–Bound ribosomes - associated with rough ER - produce proteins that work within endomembrane system or outside cell
Cells Must Distribute Materials and Dispose of Wastes
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Endomembrane system Synthesis, storage, export and destruction of molecules and wastes
Rough ER
– ‘studded’ with ribosomes
– Proteins made here enter into ER to be transported or exported
– Site of phospholipid production
Smooth ER
– Synthesis of lipids, cholesterol
– Detoxify drugs and wastes
– Storage of calcium
Golgi apparatus
– Shipping and receiving center for cell
– Receives products from ER and routes them to appropriate location
Lysosomes
– Hydrolytic enzymes; degrades macromolecules or old organelles
Vacuoles
– Site of waste/nutrient storage
– Plants - central vacuole
– Protists - contractile vacuoles and food vacuoles
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Smooth ER
Rough ER
Ribosomes
Nuclearenvelope
Rough ER
–‘studded’ with ribosomes
–Proteins made here enter into ER to be transported around or exported out of cell
–Site of phospholipid production
Smooth ER
–Synthesis of lipids, cholesterol
–Detoxify drugs and wastes
–Storage of calcium
Figure 4.8B
Transport vesiclebuds off
mRNA
Ribosome
Polypeptide
Glycoprotein
Rough ER
Sugarchain
Secretoryproteininside trans-port vesicle
4
3
2
1
Golgi apparatusGolgi apparatus
Transportvesicle fromthe Golgi
“Shipping” side of Golgiapparatus
Transportvesiclefrom ER
“Receiving” sideof Golgiapparatus
1
2
3
4
4
Golgi apparatus
–Shipping and receiving center for cell
–Receives products from ER and routes them to appropriate location
Lysosomes are digestive compartments A lysosome contains digestive enzymes (produced by ER and transferred to lysosomes via
Golgi and transport vesicles)
Lysosomes help digest food particles engulfed by a cell.
Lysosomes also help remove or recycle damaged parts of a cell.
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Animation: Lysosome Formation
Digestiveenzymes
Lysosome
Food vacuole
Plasma membrane
Digestion
Vacuoles Vacuoles are large vesicles that
have a variety of functions.
– Some protists have contractile vacuoles that help to eliminate water from the protist.
– In plants, vacuoles may
– have digestive functions,
– contain pigments, or
– contain poisons that protect the plant.
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Video: Paramecium Vacuole
Contractilevacuoles
Nucleus
Central vacuole
Chloroplast
Nucleus
ENERGY-CONVERTING ORGANELLES
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Cells require energy!!
Mitochondria - site of cellular respiration
– Cellular respiration converts the chemical energy in foods to chemical energy in ATP (adenosine triphosphate).
Chloroplasts - site of photosynthesis
Mitochondria and chloroplasts have
– DNA and
– ribosomes.
The structure of this DNA and these ribosomes is very similar to that found in prokaryotic cells.
– Endosymbiosis theory
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Figure 4.13
Matrix
Cristae
Innermembrane
Outermembrane
Mitochondrion
Intermembranespace
Figure 4.14
Inner andoutermembranes
Granum Stroma Chloroplast
Thylakoid
Honors Biology
The Great ENERGY Circle of Life
sun
ATP
Photosynthesis
Respiration
O2glucosesugarCO2 H2O+ +
plants
animals & plants
ATP
THE CYTOSKELETON AND CELL SURFACES
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Cytoskeleton gives cell shape and allows for movement
Cytoskeleton = network of protein fibers,
– Functions: Structural support and motility.
The cytoskeleton is composed of three kinds of proteins:
1. Microfilaments (actin filaments)
support the cell’s shape and are
involved in function of muscle cells
2. Intermediate filaments
3. Microtubules (made of tubulin)
composes flagella and cilia; allows for movement by pseudopodia
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Video: Cytoplasmic Streaming
Figure 4.16
Actin subunit
Nucleus
Nucleus
Microfilament Intermediate filament
Fibrous subunits
7 nm 10 nm
Tubulin subunits
Microtubule
25 nm
Cilia and flagella
Functions of cilia and flagella:
– Movement
– Animal sperm cells
– protists
– Trap food particles/debris
– Cells that sweep mucus out of our lungs have cilia
– Oviducts of females
– Sensory
– Lining of nostrils; hair cells in ears
Composed of microtubules
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Video: Chlamydomonas
Video: Paramecium Cilia
Cilia
Flagellum
Figure 4.17C
Outer microtubule doublet
Centralmicrotubules
Radial spoke
Dynein proteins
Plasma membrane
Extracellular Matrix in Animals
Animal cells synthesize and secrete an elaborate ECM
– Composed of sugar-protein polymers
– helps hold cells together in tissues and
– protects and supports the plasma membrane.
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EXTRACELLULAR FLUID
CYTOPLASMMicrofilamentsof cytoskelton
Plasmamembrane
Integrin
Connectingglycoprotein
Glycoproteincomplexwith longpolysaccharide
Collagen fiber
ECM is glue that holds animal cells together!!