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Cell Structure

Cell Structure. Chapter 4. Cells are Us. Muscle Cell. Muscle Fibers: elongated cylindrical cells that run parallel to each other. Sarcolemma : a plasma membrane that covers each membrane. Cell Theory. There are 100 Trillion Cells in the human body. 20 Trillion Red Blood Cells .

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Cell Structure

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  1. Cell Structure Chapter 4

  2. Cells are Us

  3. Muscle Cell

  4. Muscle Fibers: elongated cylindrical cells that run parallel to each other. • Sarcolemma: a plasma membrane that covers each membrane.

  5. Cell Theory • There are 100 Trillion Cells in the human body. • 20 Trillion Red Blood Cells. • Do not have nuclei when mature. But newly formed cells do have a nucleus. • 300 Million Brain Cells. Neurons.

  6. Red and white blood cells above vessel-forming cells. nerve cell Cells are Us A person contains about 100 trillion cells. That’s 100,000,000,000,000 or 1 x 1014 cells. There are about 200 different cell types in mammals (one of us). Cells are tiny, measuring on average about 0.002 cm (20 um) across. That’s about 1250 cells, “shoulder-to-shoulder” per inch.

  7. Cell Theory • The Cell is the basic unit of structure and function of living things.  • The first major use of the microscope was by Anton von Leeuwenhoek. • Dutch Biologist who observed the first microbes while looking at a sample of pond water. • He called them “Wee Beasties”.

  8. Cell Theory Cells were discovered in 1665 by Robert Hooke. He was inspired by Leeuwenhoek and began looking at multicellular organisms. Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) - Rudolf Virchow (1840) .

  9. Cell Theory • C. Robert Brown: Discovered the nucleus of the cell. (1831)

  10. Schleiden Schwann The Cell Theory The cell theory (proposed independently in 1838 and 1839) is a cornerstone of biology. All organisms are composed of one or more cells. Cells are the smallest living things. Cells arise only by division of previously existing cells. All organisms living today are descendents of an ancestral cell. Virchow

  11. Cell Theory Cell Theory 1. All organisms are composed of cells. 2. Cells are the smallest living things. 3. Cells arise only from pre-existing cells. All cells today represent a continuous line of descent from the first living cells.

  12. It’s Crowded In There A micrograph showing cytoskeleton (red), ribosomes (green), and membrane (blue)

  13. Cell Theory Cell size is limited. -As cell size increases, it takes longer for material to diffuse from the cell membrane to the interior of the cell. Surface area-to-volume ratio: as a cell increases in size, the volume increases 10x faster than the surface area

  14. Cell Theory

  15. Cell Theory All cells have certain structures in common. 1. genetic material – in a nucleoid or nucleus 2. cytoplasm – a semifluid matrix 3. plasma membrane – a phospholipid bilayer

  16. Prokaryotic Cells Prokaryotic cells lack a membrane-bound nucleus. -genetic material is present in the nucleoid Two types of prokaryotes: -archaea -bacteria

  17. A Sense of Scale and Abundance – Bacteria on the Head of a Pin

  18. Prokaryotic Cells Prokaryotic cells possess -genetic material in the nucleoid -cytoplasm -plasma membrane -cell wall -ribosomes -no membrane-bound organelles

  19. Prokaryotic Cells

  20. Prokaryotic Cells Prokaryotic cell walls -protect the cell and maintain cell shape Bacterial cell walls -may be composed of peptidoglycan -may be Gram positive or Gram negative Gram Positive react to antibiotics Gram Negative Bacteria do not. Archaean cell walls lack peptidoglycan.

  21. Prokaryotic Cells Flagella -present in some prokaryotic cells -used for locomotion -rotary motion propels the cell

  22. Prokaryotic Cells

  23. Eukaryotic Cells Eukaryotic cells -possess a membrane-bound nucleus -are more complex than prokaryotic cells -compartmentalize many cellular functions within organelles and the endomembrane system -possess a cytoskeleton for support and to maintain cellular structure

  24. Eukaryotic Cells

  25. Eukaryotic Cells

  26. Eukaryotic Cells Nucleus -stores the genetic material of the cell in the form of multiple, linear chromosomes -surrounded by a nuclear envelope composed of 2 phospholipid bilayers -in chromosomes – DNA is organized with proteins to form chromatin

  27. Eukaryotic Cells

  28. A prokaryotic cell A eukaryotic cell Two Fundamentally Different Types of Cells

  29. Us vs. Them -Eukaryotes and Prokaryotes

  30. Eukaryotic Cells Ribosomes -the site of protein synthesis in the cell -composed of ribosomal RNA and proteins -found within the cytosol of the cytoplasm and attached to internal membranes

  31. Ribosome • Site of protein synthesis • Found attached to rough ER or floating free in cytosol • Produced in a part of the nucleus called the nucleolus

  32. Endomembrane System Endomembrane system -a series of membranes throughout the cytoplasm -divides cell into compartments where different cellular functions occur 1. endoplasmic reticulum 2. Golgi apparatus 3. lysosomes

  33. Endomembrane System Rough endoplasmic reticulum (RER) -membranes that create a network of channels throughout the cytoplasm -attachment of ribosomes to the membrane gives a rough appearance -synthesis of proteins to be secreted, sent to lysosomes or plasma membrane

  34. Endomembrane System Smooth endoplasmic reticulum (SER) -relatively few ribosomes attached -functions: -synthesis of membrane lipids -calcium storage -detoxification of foreign substances

  35. Endomembrane System

  36. Endomembrane System Golgi apparatus -flattened stacks of interconnected membranes -packaging and distribution of materials to different parts of the cell -synthesis of cell wall components

  37. Endomembrane System Lysosomes -membrane bound vesicles containing digestive enzymes to break down macromolecules -destroy cells or foreign matter that the cell has engulfed by phagocytosis

  38. Endomembrane System Microbodies -membrane bound vesicles -contain enzymes -not part of the endomembrane system -glyoxysomes in plants contain enzymes for converting fats to carbohydrates -peroxisomes contain oxidative enzymes and catalase

  39. Endomembrane System Vacuoles -membrane-bound structures with various functions depending on the cell type There are different types of vacuoles: -central vacuole in plant cells -contractile vacuole of some protists -vacuoles for storage

  40. Vacuoles • Large central vacuole usually in plant cells • Many smaller vacuoles in animal cells • Storage container for water, food, enzymes, wastes, pigments, etc. What type of microscope may have been used to take this picture?

  41. Mitochondria Mitochondria -organelles present in all types of eukaryotic cells -contain oxidative metabolism enzymes to breakdown and transform Glucose to Energy (ATP).

  42. The Mitochondrion Think of the mitochondrion as the powerhouse of the cell. Both plant and animal cells contain many mitochondria. (Mitochondria is the plural of mitochondrion)

  43. Mitochondria -surrounded by 2 membranes -smooth outer membrane -folded inner membrane with layers called cristae -intermembrane space is located between the two membranes -contain their own DNA

  44. Mitochondria

  45. The Mitochondrion A class of diseases that causes muscle weakness and neurological disorders are due to malfunctioning mitochondria. Worn out mitochondria may be an important factor in aging.

  46. Mitochondrial Diseases

  47. Mitochondria and Health

  48. Chloroplasts Chloroplasts -organelles present in cells of plants and some other eukaryotes -contain chlorophyll for photosynthesis -surrounded by 2 membranes -thylakoids are membranous sacs within the inner membrane -grana are stacks of thylakoids

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