Cell Structure and Function Chapter 4 Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles! Nucleus Outline! Endomembrane System! Cytoskeleton! Centrioles, Cilia, and Flagella 1 2 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. 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. 3 4
Organism Sizes 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. 5 6 Cell Envelopes Prokaryotic Cells Includes plasma membrane, cell wall, and glycocalyx (layer of polysaccharides outside cell wall).! Capsule Well-organized layer. Form internal pouches (mesosomes). Cytoplasm Prokaryotic Cells Cytoplasm is a semifluid solution encapsulated by plasma membrane.! Inclusion Bodies - Stored granules of various substances. Appendages Flagella Fimbriae Sex Pili 7 8
Prokaryotic Cells 9 10 Eukaryotic Cells Members of domain Eukarya. Contain membrane-bounded nucleus. Contain specialized organelles. Contain plasma membrane. Organelles Organelles of endomembrane system communicate with one another. Basically self-sufficient Compartmentalization allows eukaryotic cells to be larger than prokaryotic cells. 11 12
Animal Cell Anatomy Plant Cell Anatomy Mader: Biology 8th Ed. Mader: Biology 8th Ed. 13 Nucleus 14 Anatomy of Nucleus Contains chromatin in semifluid nucleoplasm. Condense to form chromosomes. Separated from cytoplasm by doublemembrane nuclear envelope. Nuclear pores permit passage in and out of the nucleus. Mader: Biology 8th Ed. Mader: Biology 8th Ed. 15 16
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. 17 18 Endomembrane System Endoplasmic Reticulum 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. 19 20
Golgi Apparatus Endomembrane System Consists of flattened, curved saccules. Modifies proteins and lipids and packages them in vesicles. Lysosomes Endomembrane System Membrane-bounded vesicles produced by the Golgi apparatus.! Engage in digestion of molecules and apoptosis (programmed cell death). 21 22 24 23 24
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. 25 26 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 27 28
Chloroplast Structure 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. 29 30 Mitochondrion Structure Cytoskeleton Cytoskeleton serves as internal skeleton that maintains cell shape and assists in movement of its parts. Actin Filaments! Pseudopods Intermediate Filaments Microtubules 31 32
Fig. 4.18 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. 33 34 Cell Theory Cell Size Prokaryotic Cells Eukaryotic Cells Organelles! Nucleus Review! Endomembrane System! Cytoskeleton! Centrioles, Cilia, and Flagella 35 36
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