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Cell Structure and Function

Cell Structure and Function. Attributes of cells. A. Plasma membrane B. DNA C. Cytoplasm D. Obtain energy and nutrients from their environment . Cell Size. 1. 1–100µm 2. Why is there a limit to cell size? a. Surface-to-volume ratio b. Distance from surface to center .

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Cell Structure and Function

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  1. Cell Structure and Function

  2. Attributes of cells A. Plasma membrane B. DNA C. Cytoplasm D. Obtain energy and nutrients from their environment

  3. Cell Size 1. 1–100µm 2. Why is there a limit to cell size? a. Surface-to-volume ratio b. Distance from surface to center

  4. tallest trees adult human chicken egg frog embryo most eukaryotic cells mitochondrion most bacteria virus proteins diameter of DNA double helix atoms

  5. Cell types Prokaryotic—no nucleus, circular DNA, ribosomes Eukaryotic—larger, nucleus, linear chromosomes, membranous organelles

  6. Prokaryotic Cells • Have no membrane-bound organelles • Include true bacteria • On earth 3.8 million years • Found nearly everywhere • Spores in each breath; intestines • Naturally in soil, air, hot springs

  7. nucleoid (DNA) ribosomes food granule prokaryotic flagellum plasma membrane cell wall cytoplasm

  8. Eukaryotic Cells • Have numerous internal structures • Various types & forms • Plants, animals, fungi, protists • Multicellular organisms

  9. nuclear pore chromatin (DNA) nucleus nucleolus nuclear envelope flagellum intermediate filaments cytoplasm plasma membrane rough endoplasmic reticulum ribosome lysosome microtubules smooth endoplasmic reticulum Golgi complex free ribosome vesicle mitochondrion vesicle

  10. microtubules (part of cytoskeleton) mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle cell wall rough endoplasmic reticulum plasma membrane nucleolus nuclear pore nucleus chromatin nuclear envelope intermediate filaments free ribosome ribosomes

  11. Eukaryotic cell structure • Nucleus is control center of the cell • 1. Membrane bound (nuclear envelope) • 2. Contains nucleoli; synthesizes ribosomal RNA • 3. DNA in chromosomes (DNA and proteins)

  12. nuclear envelope nucleolus nuclear pores chromatin

  13. nucleus nuclear pores

  14. chromatin chromosome

  15. 0.05 micrometers

  16. Eukaryotic cell structure Organelles Endoplasmic reticulumconsists of folded membranes attached to the nucleus Rough ERis site of protein synthesis and protein secretion

  17. rough endoplasmic reticulum ribosomes 0.5 micrometers smooth endoplasmic reticulum 0.5 micrometers vesicles

  18. Eukaryotic Cell Structure Organelles (cont.) Ribosomesassemble amino acid into polypeptide chains • a. Associated with the ER • b. Composed of RNA and proteins

  19. ribosomes rough endoplasmic reticulum 0.5 micrometers

  20. vesicles smooth endoplasmic reticulum 0.5 micrometers

  21. Eukaryotic Cell Structure • Organelles (cont.) • Golgi apparatus are membranous sacs associated with ER • a. Processing and transport of proteins, lipids • b. Synthesis and transport of polysaccharides

  22. vesicles from ER vesicles leaving Golgi complex Golgi complex

  23. Eukaryotic cell structure • Organelles (cont.) • Lysosomes are Golgi-derived vesicles containing digestive enzymes

  24. vesicles from ER vesicles leaving Golgi complex Golgi complex

  25. Eukaryotic Cells: OrganellesEnergy sources for cell activities • Mitochondria provide energy for cellular functions (respiration) • a. Membrane bound, numerous • b. Matrix/cristae • c. Have their own DNA and ribosomes; self-replicate

  26. 5 micrometers

  27. Eukaryotic Cells: OrganellesEnergy sources for cell activities • Chloroplasts—function in photosynthesis • 1) Green—contain chlorophyll pigment • 2) Stroma/grana (thylakoid stacks) • 3) Have their own DNA and ribosomes; self-replicate • 4) Up to 100 per cell

  28. Eukaryotic Cells: Organelles • Cytoskeleton • Internal infrastructure • Surface structures • extensions of the plasma membrane • aid in movement of simple organisms

  29. actin subunits subunit tubulin subunit

  30. Prokaryotes & Eukaryotes • Similarities & differences • Both surrounded by plasma membrane, but very different • Prokaryotes – Archaebacteria and Eubacteria • Eukaryotes – everything else

  31. Evolution of Eukaryotic cell Endosymbiotic Hypothesis • Similarities between bacteria, mitochondria and chloroplasts • Self-reproducing by binary fission • Size of organism and genome • Single circular naked DNA • Proportion of (G & C) to (A & T) • Same sized ribosome • Protein synthesis inhibited by antibiotics • Enzymes for synthesis of DNA, RNA and protein • Electron transport system

  32. Plant & Animal Cells • Similarities • Both constructed from eukaryotic cells • Both contain similar organelles • Both surrounded by cell membrane

  33. Plant & Animal Cells • Differences • Plants have • Cell wall – provides strength & rigidity • Have chloroplasts, photosynthetic • Animals have • Other organelle not found in plants (lysosomes formed from Golgi) • Centrioles, important in cell division

  34. Brief Look at Viruses • Viruses are acellular • Not considered to be living • Cause serious diseases in most organisms

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