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Exploring Cellular Structures: From Cytology to Organelles

Delve into the world of cytology, examining cell types like Procaryotic and Eucaryotic cells. Explore cellular boundaries, cytoplasmic organelles like ribosomes, mitochondria, and nuclei, along with their functions and significance. Understand the internal structures of flagella, cilia, and the intricate processes within cells. This comprehensive guide provides an in-depth look at the fascinating realm of cell biology and its components.

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Exploring Cellular Structures: From Cytology to Organelles

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  1. Cytology The study of cells

  2. Cell Types 1) Procaryotic 2) Eucaryotic

  3. Procaryotic Cells Cells lack a true nucleus Cells have only non-membrane bound organelles Bacteria and some algae

  4. Eucaryotic Cells Cells have a true nuclues Cells have membrane bound organelles Most protists All fungi, plants, animals, and humans

  5. Cellular Structures 1) Boundary 2) Cytoplasm 3) Nucleus

  6. Cellular Boundaries • Plasma membrane • Cell wall • Middle lamella • Capsule / sheath / slime coat

  7. Plasma membrane • The outermost boundary of all cells • Semi-permeable • Phospholipid bilayer • Proteins are embedded within • transportation • cell recognition • cell adhesion

  8. Plasma membrane

  9. Laminin video clip by louiegiglio

  10. Cell wall • Rigid structure surrounding some cells • all procaryotes • plants, algae, fungi, and protozoans • Porous • Composed of cellulose or chitin

  11. Middle lamella • Layer between two adjacent cell walls • Acts as a lubricant

  12. Capsule / Sheath / Slime coat • A cellular secretion of polysaccharides • Surrounds unicellular or colonial organisms • Protective • Attackers must first dissolve the capsule or penetrate it

  13. Cytoplasmic matrix Ribosomes Endoplasmic reticulum Mitochondria Plastids Golgi body Lysosomes Vacuoles Centrioles Flagellum Cilia Cytoplasmic Organelles

  14. Cytoplasmic Matrix(aka: the cytoplasm) • Located in all types of cells • A semi-solid watery substance in which all other organelles are suspended • Think “jello salad” • Provides structure to the cell thanks to its cytoskeleton • Cytoplasmic streaming – contents are always moving

  15. Ribosome • Located in all types of cells • Mass of proteins and RNA • Function: protein synthesis

  16. Endoplasmic Reticulum • Seen only in eukaryotic cells • Folds of cellular membranes • Continuous with both the plasma membrane and the nuclear membrane • Functions: • Provide flexible but structural shape • Synthesis of proteins, lipids, & polysaccharides • Movement of substances throughout the cell

  17. Types of ER’s

  18. Mitochondria • Seen only in eukaryotic cells • A double-membrane bound bean shape structure • Inner membrane is folded to form cristae • Function: cellular respiration • Quantity is dependent on the activity level of the cell

  19. Mitochondria

  20. Plastids • Seen only in plants and algae • A double-membrane bound structure • Function: synthesis and storage of polysaccharides

  21. Types of Plastids • Chromoplasts • Contains the pigments used in synthesizing polysaccharides • Given specific names based on the type of pigment in the chromoplast • Most important chromoplast: the chloroplast (green pigment)

  22. Chloroplast • Inner membrane is folded to form the thylakoid • Stack of thylakoids is called a grana • Fluid within the chloroplast is called stroma

  23. Types of Plastids • Leucoplasts • Colorless structure • Function: a storehouse of starch • Most numerous in the fleshy, storage areas of plants

  24. Golgi body • Seen only in eukaryotic cells • A flat, curved, membrane structure • Function: • Synthesizing polysaccharides • Final modifications of proteins & lipids for their final destination

  25. Lysosome • Seen only in eukaryotic cells • Small, membrane bound spherical structure • Contains digestive enzymes • Function: • digestion of old, used organelles • digestion of invading cells

  26. Vacuoles • Seen only in eukaryotic cells • Function: storage • 4 types of vacuoles • Phagocytic • Pinocytic • Waste • Contractile

  27. Types of Vacuoles • Phagocytic • Storage of food • Formed by phagocytosis • Pinocytic • Storage of water • Formed by pinocytosis • Waste • Storage of nondigestible material • Fuses with the plasma membrane to release material

  28. Types of Vacuoles • Contractile vacuole • Found in unicellular organisms that live in a freshwater environment • Collects excess water and pushes the water back out of the cell

  29. Centriole • Seen only in eukaryotic cells, except plants • 2 cylinders occurring at right angles to each other • Always located near the nucleus • Function: cell division

  30. Flagellum • Located in all types of cells • Long, tubular extension of the cytoskeleton within the cytoplasm • Small quantity: usually have 1 – 4 flagella on a cell • Function: locomotion of the cell

  31. Cilia • Located in all types of cells • Short extensions of the cytoskeleton • Usually covers the entire cell or a large section of a cell • Function: locomotion of the cell or movement of substances within an organism

  32. Internal Structure of Cilia & Flagella • Both have the same internal structures • Both structures have been used to disprove evolution • Irreducibly complex

  33. Nucleus(the control center of the cell) • Nuclear envelope • Chromatin material • Nucleolus

  34. Nuclear Envelope • Seen only in eukaryotic cells • Porous • Phospholipid bilayer • Continuous with the endoplasmic reticulum

  35. Chromatin Material • Seen in all types of cells • Long, thin strands consisting of DNA and proteins • Function: codes for the information needed for protein synthesis • DNA permits activity of a cell, but it does not decide what the cell is capable of doing • DNA was programmed by God at creation

  36. Nucleolus • An area with a large concentration of RNA (a substance similar to DNA)

  37. Review of Cellular Structures

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