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Cell Structure and Function

Cell Structure and Function. Cell Theory. A unifying concept in biology States that: All organisms are composed of cells All cells come only from preexisting cells Smallest unit of life. Unicellular Organisms. Single-celled organisms Must be able to perform all life functions

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Cell Structure and Function

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  1. Cell Structure and Function

  2. Cell Theory • A unifying concept in biology • States that: • All organisms are composed of cells • All cells come only from preexisting cells • Smallest unit of life

  3. Unicellular Organisms • Single-celled organisms • Must be able to perform all life functions • Obtain gases & food • Remove wastes • Produce energy • Perform cellular respiration • Grow • Reproduce

  4. Multicellular Organisms • Cells within organism are specialized to perform particular functions: • Cells – smallest level of organization • Tissues – groups of cells (muscle, nerve) • Organ – groups of tissues (stomach, leaf) • System – groups of organs (respiratory, nervous) • Organism – groups of systems

  5. Cell Size • Most cells much smaller than one millimeter (mm) • Some as small as one micrometer (mm) • Size restricted by Surface/Volume (S/V) ratio • Surface is membrane, across which cell acquires nutrients and expels wastes • Volume is living cytoplasm, which demands nutrients and produces wastes • As cell grows, volume increases faster than surface • Cells specialized in absorption modified to greatly increase surface area per unit volume

  6. Surface to Volume Ratio TotalSurfaceArea (HeightWidthNumberOfSidesNumberOfCubes) 96 cm2 192 cm2 384 cm2 TotalVolume (HeightWidthLengthXNumberOfCubes) 64 cm3 64 cm3 64 cm3 SurfaceAreaPerCube/VolumePerCube (SurfaceArea/Volume) 1.5/1 3/1 6/1

  7. Prokaryotic Cells:Domains • Lack a membrane-bound nucleus • Structurally simple • Two domains: • Bacteria • Three Shapes • Bacillus (rod) • Coccus (spherical) • Spirilla (spiral) • Archaea • Live in extreme habitats

  8. Eukaryotic Cells • Domain Eukarya • Protists • Fungi • Plants • Animals • Cells contain: • Membrane-bound nucleus • Specialized organelles • Plasma membrane

  9. Eukaryotic Cells :Organelles • Within a cell there is a division of labor. • The specialized parts of the cell that carry out specific functions are known as organelles.

  10. Plasma Membrane • Thin, flexible membrane surrounding the cell • Selectively permeable • Life Functions – excretion, regulation

  11. Plasma Membrane

  12. Cytoplasm • Jelly-like material inside cell. • Contains the important structures • 70% water • Life Functions - transport

  13. Cell Wall • Found in plants, fungi, algae and most prokaryotes • Outside cell membrane • Provides support and protection

  14. Animal Cell Anatomy

  15. Plant Cell Anatomy

  16. Nucleus • Command center of cell, usually near center • Separated from cytoplasm by nuclear envelope • Contains chromatin • Chromatin contains DNA of genes • Condenses to form chromosomes • Dark nucleolus • Life functions – regulation, reproduction

  17. Ribosomes • Serve in protein synthesis • May be located: • On the endoplasmic reticulum (thereby making it “rough”), or • Free in the cytoplasm, either singly or in groups called polyribosomes • Life functions - Synthesis

  18. Vacuoles • Membranous sacs that • Store materials that occur in excess • Others very specialized (contractile vacuole) • Plants cells typically have a central vacuole • Up to 90% volume of some cells • Functions in: • Storage of water, nutrients, pigments, and waste products • Development of turgor pressure • Some functions performed by lysosomes in other eukaryotes

  19. Vacuoles

  20. Energy-Related Organelles:Chloroplast Structure • Bounded by double membrane • Green due to chlorophyll • Green photosynthetic pigment • Found ONLY in inner membranes of chloroplast

  21. Energy-Related Organelles:Chloroplasts • Captures light energy to drive cellular machinery • Photosynthesis • Synthesizes carbohydrates from CO2 & H2O • Makes own food using CO2 as only carbon source • Energy-poor compounds converted to energy rich compounds • Life function - Synthesis

  22. Energy-Related Organelles:Chloroplast Structure

  23. Energy-Related Organelles:Mitochondria • Bounded by double membrane • Involved in cellular respiration • Produce most of ATP utilized by the cell • Life functions - Respiration

  24. Energy-Related Organelles:Mitochondrial Structure

  25. Microtubular Arrays:Centrioles • Short, hollow cylinders • One pair per animal cell • Located in centrosome of animal cells • Oriented at right angles to each other • Separate during mitosis to determine plane of division

  26. Cytoskeleton:Centrioles

  27. Endoplasmic reticulum (smooth) vacuole E.R. (rough) mitochondria ribosomes pores nucleolus Cell membrane ribosome nucleus lysosome Golgi body (apparatus) centrioles nuclear envelope

  28. ribosomes E. R. nucleolus large vacuole leucoplast Golgi body nucleus cell wall nuclear envelope cell membrane mitochondrion chloroplasts

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