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Mader: Biology 8th Ed.
Cell Structure and Function
Chapter 4
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Mader: Biology 8th Ed.
Outline
• Cell Theory
• Cell Size
• Prokaryotic Cells
• Eukaryotic Cells
– Organelles
!Nucleus
!Endomembrane System
!Cytoskeleton
!Centrioles, Cilia, and Flagella
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Mader: Biology 8th Ed.
Cell Theory
• Cell theory states all organisms are composed of cells and that cells come only from preexisting cells.
– One of unifying concepts of biology.
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Cell Size
• Most cells are much smaller than one millimeter.
– Some as small as one micrometer.
• Small cells are likely to have an adequate surface area for exchanging wastes for nutrients.
– Cells that specialize in absorption have modifications that greatly increase the surface area per volume of the cell.
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Organism Sizes
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Prokaryotic Cells
• Lack a membrane-bounded nucleus.• Structurally simple.• Can be divided into two domains:
– Bacteria !Three Shapes
"Bacillus (rod)"Coccus (spherical)"Spirilla (spiral)
– Archaea!Live in extreme habitats.
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Prokaryotic Cells
• Cell Envelopes
– Includes plasma membrane, cell wall, and glycocalyx (layer of polysaccharides outside cell wall).
!Capsule – Well-organized layer.
– Form internal pouches (mesosomes).
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Prokaryotic Cells
• Cytoplasm
– Cytoplasm is a semifluid solution encapsulated by plasma membrane.
!Inclusion Bodies - Stored granules of various substances.
• Appendages
– Flagella
– Fimbriae
– Sex Pili
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Prokaryotic Cells
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Eukaryotic Cells
• Members of domain Eukarya.
• Contain membrane-bounded nucleus.
• Contain specialized organelles.
• Contain plasma membrane.
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Organelles
• Organelles of endomembrane system communicate with one another.
– Basically self-sufficient
• Compartmentalization allows eukaryotic cells to be larger than prokaryotic cells.
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Animal Cell Anatomy
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Plant Cell Anatomy
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Nucleus
• Contains chromatin in semifluid nucleoplasm.
– Condense to form chromosomes.
• Separated from cytoplasm by double-membrane nuclear envelope.
– Nuclear pores permit passage in and out of the nucleus.
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Anatomy of Nucleus
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Ribosomes
• Composed of large and small subunits that serve in protein synthesis.
– Subunits made in nucleolus.
• Occur singly and in groups, and may become attached to endoplasmic reticulum.
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Endomembrane System
• Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and several types of vesicles.
– Restrict enzymatic reactions to specific compartments within cell.
• Endoplasmic Reticulum
– Rough - Studded with ribosomes.
– Smooth - No ribosomes.
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Endoplasmic Reticulum
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Endomembrane System
• Golgi Apparatus
– Consists of flattened, curved saccules.
– Modifies proteins and lipids and packages them in vesicles.
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Endomembrane System
• Lysosomes
– Membrane-bounded vesicles produced by the Golgi apparatus.
!Engage in digestion of molecules and apoptosis (programmed cell death).
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Peroxisomes and Vacuoles
• Peroxisomes are membrane-bounded vesicles that enclose enzymes.
– Enzymes are cell-specific
• Vacuoles are membranous sacs that are larger than vesicles.
– Store substances
– Plants cells typically have a central vacuole that functions in storage of nutrients and waste products.
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Energy-Related Organelles
• Chloroplasts use solar energy to synthesize carbohydrates.– Photosynthesis
!Cellular Respiration– Adenosine triphosphate (ATP) is used for
all energy-requiring processes in cells.• Chloroplasts are green due to the green
pigment chlorophyll.– Stroma– Granum
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Chloroplast Structure
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Energy-Related Organelles
• Mitochondria are involved in cellular respiration.
• Produce most of ATP utilized by the cell.
– Cristae - Inner membrane that encloses matrix.
– Matrix - Enzymes that break down nutrient molecules.
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Mitochondrion Structure
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Cytoskeleton
• Cytoskeleton serves as internal skeleton that maintains cell shape and assists in movement of its parts.
– Actin Filaments
!Pseudopods
– Intermediate Filaments
– Microtubules
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Fig. 4.18
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Centrioles, Cilia, and Flagella
• Centrioles are short cylinders with a 9 + 0 pattern of microtubule triplets that may give rise to basal bodies of cilia and flagella.
• Cilia and flagella are hairlike projections with a 9 + 2 pattern of microtubules that aid in cell movement.
– In eukaryotes, cilia are much shorter than flagella.
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Review
• Cell Theory
• Cell Size
• Prokaryotic Cells
• Eukaryotic Cells
– Organelles
!Nucleus
!Endomembrane System
!Cytoskeleton
!Centrioles, Cilia, and Flagella
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