1 / 90

Honors Biology: Chapter 4

Honors Biology: Chapter 4. A Tour of the Cell. The Art of Looking at Cells Artists have long found inspiration in the visual richness of the living world Conversely, scientists use art to illustrate their findings Micrographs show structures as scientists see them

nami
Download Presentation

Honors Biology: Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Honors Biology: Chapter 4 A Tour of the Cell

  2. The Art of Looking at Cells • Artists have long found inspiration in the visual richness of the living world • Conversely, scientists use art to illustrate their findings • Micrographs show structures as scientists see them • Drawings can emphasize details

  3. Biology is a visual science Wasily Kandinsky (1866-1944) – is it based on a cell? Santiago Ramon y Cajal (1852-1934) anatomist - Nerve cells in the retina

  4. Contributions to The Cell Theory • Zaccharias Jansen – first compound scope • Robert Hooke 1660s – term for “cells” • Saw cork cell walls • Tiny compartments • Called them “cells”

  5. Anton von Leeuwenhoek • Anton von Leeuwenhoek 1660s • first high-mag microscope • living cells, bacteria • Pond water, blood, saliva

  6. Other cell discoveries • Robert Brown – 1830s • nucleus in all cells • Matthias Schleiden 1830s • all plants made of cells • Theodore Schwann 1830s • all animals made of cells • Rudolf Virchow 1850s • new cells come from cell division

  7. The Cell Theory • All organisms are made of one or more cells • The cell is the basic unit of life. Cells that form part of a larger organism still do their own life processes. • All cells come from pre-existing cells

  8. 4.2 Why are all cells small? Cells vary in size and shape • Must be big enough to contain raw materials and molecules needed by cell • Must be small enough to have fast exchange with environment Surface area must be large compared to volume 5

  9. Cells have a large Surface-to-Volume Ratio size increases 2Xarea increases 4X volume increases 8X 6

  10. Most cells are microscopic

  11. Two basic kinds of cells ProkaryoticEukaryotic small and simple larger and more complex no nucleus nucleus bacteria all other organisms Both have: DNA & complex chemicals cell membrane cytoplasmribosomes

  12. Two kinds of cells – small and large Bacteria (purple) in animal cell (pink)

  13. LE 4-3a Prokaryotic cell Two kinds of cells Simple and complex Nucleoid region Colorized TEM 15,000 Nucleus Organelles Eukaryotic cell

  14. Prokaryotic cells“before nucleus” • Very small (1-10mm) • No nucleus or other membrane-bound organelles • DNA in nucleoid region in cytoplasm

  15. ALL prokaryotes have 1. Cell (plasma) membrane • Encloses cytoplasm, selectively permeable • Controls what enters and leaves cell 2. Nucleoid • Region containing DNA in a chromosome 3. Cell wall – various kinds of polysaccharides • Outside cell membrane • Cell shape and protection

  16. SOME prokaryotes have 4. Capsule – protective layer • Slimy or sticky coating, outside cell wall 5. Pili – extensions of cytoplasm and membrane • to attach to other cells, pass signals 6. Prokaryotic flagella – for movement 7. Plasmids – small rings of DNA • For sexual reproduction • have their own genes

  17. Some prokaryotic (bacterial) cells Common shapes of bacteria

  18. Eukaryotes “true nucleus” • 4.4 Eukaryotic cells are partitioned into compartments • Larger than prokaryotic (10-100 m) • Many organelles – tiny “organs”, specific functions • Most organelles are enclosed by membrane • Compartments - different metabolic processes • Keeps chemistry inside organelle separate from rest of cell • Enzymes often are parts of the membranes, greatly increase surface for reactions

  19. Eukaryotic Cells The cell is like a city – every part has a job to do. Together these parts keep the cell alive.

  20. LE 4-4a Smooth endoplasmic reticulum Rough endoplasmic reticulum Nucleus Flagellum Not in most plant cells Lycosome Centriole Ribosomes Peroxisome Golgi apparatus Microtubule Intermediate filament Plasma membrane Cytoskeleton Microfilament Mitochondrion

  21. LE 4-4b Rough endoplasmic reticulum Nucleus Ribosomes Smooth endoplasmic reticulum Golgi apparatus Microtubule Intermediate filament Central vacuole Cytoskeleton Not in animal cells Microfilament Chloroplast Cell wall Mitochondrion Peroxisome Plasma membrane

  22. Cytoplasm • Cytoplasm: Watery solution outside nucleus • Contains organelles, each has a function • Many dissolved substances for metabolism • Site for chemical reactions Cytoplasm and nucleus work together

  23. 4.5 Nucleus: the cell's genetic control center • Has MOST of a cell’s DNA • DNA in chromosomes • Chromatin - loose, thread-like form of chromosome in • non-dividing cell • Controls cell by directing synthesis of proteins Also contains nucleolus – makes ribosomes

  24. Structures in a nucleus • Nucleolus – makes ribosomes chromatin Nuclear pores Nuclear membrane nucleolus

  25. Nuclear Envelope • Double-layered membrane surrounding nucleus • Many pores for molecules to pass through • Selectively permeable – controls what moves in and out of nucleus

  26. Nuclear pores Control flow of materials in and out of nucleus

  27. 4.6 Endomembrane System • A collection of membranous organelles • - divide the cell into compartments • - work together to synthesize, store, and export molecules • Example: Endoplasmic reticulum (ER) • Continuous network of flattened sacs and tubes throughout cell

  28. LE 4-5 Nucleus Chromatin Two membranes of nuclear envelope Nucleolus Pore Rough endoplasmic reticulum Ribosomes

  29. 4.8 Rough Endoplasmic Reticulum • Rough ER makes membrane and proteins • Ribosomes on membrane make proteins • RER modifies proteins made by ribosomes and transports to other parts of cell • Some sent to Golgi body for further processing

  30. Organelles that Build Proteins Ribosomes Make proteins, use instructions in DNA Made of RNA and protein Made in nucleolus, move to cytoplasm and rough ER

  31. LE 4-7 Smooth ER Rough ER Nuclear envelope Ribosomes Smooth ER Rough ER TEM 45,000

  32. LE 4-8 Transport vesicle buds off Secretary (glyco-) protein inside trans- port vesicle Ribosome Sugar chain Glycoprotein Polypeptide Rough ER

  33. 4.7 Smooth Endoplasmic Reticulum No ribosomes on membrane • Smooth ER has a variety of functions • Synthesizes lipids • In liver cells, processes materials such as toxins and drugs • In muscle cells, stores and releases calcium ions needed for muscle contraction

  34. 4.9 Golgi Body • The Golgi apparatus finishes, sorts, and ships cell products • Stacks of flattened membrane sacs • Receives and modifies proteins from ER • Sorts, packages into tiny vesicles • Final products may be used inside cell – ex. Lysosomes • Some exported – ex. Hormones, neurotransmitters

  35. LE 4-9 Golgi apparatus Golgi apparatus “Receiving” side of Golgi apparatus Transport vesicle from ER New vesicle forming “Shipping” side of Golgi apparatus TEM 130,000  Transport vesicle from the Golgi

  36. 4.10 Lysosomes –digestive compartments Lysosomes are sacs of enzymes that form from the Golgi apparatus • Break down wastes and worn-out cell parts • Recycle molecules the cell can use • In protozoans, bind to food vacuole to digest food • In white blood cells, destroy bacteria that have been ingested • In development, removes tissues no longer needed • Cell death, when cell is damaged beyond repair Animation: Lysosome Formation

  37. LE 4-10a Rough ER Transport vesicle (containing inactive hydrolytic enzymes) Plasma membrane Golgi apparatus Engulfment of particle Lysosome engulfing damaged organelle “Food” Lysosomes Food vacuole Digestion

  38. LE 4-10b Lysosome Nucleus Lysosomes are stained in this slide TEM 8,500 

  39. Lysosome containing two damaged organelles Mitochondrion fragment TEM 42,500  Peroxisome fragment

  40. 4.11 Abnormal lysosomes • Lysosomal storage diseases can be fatal • Result from an inherited lack of one or more lysosomal enzymes • Interfere with various cell functions • Ex. Tay-Sachs Disease, Pompe’s disease

  41. Peroxisomes – break down peroxide Peroxisomes (microbodies) – break down hydrogen peroxide, made in cell reactions - other chemical functions in certain cells - peroxisome disorders include ALD

  42. 4.12 Vacuoles store substances Food vacuoles in paramecium

  43. Plant Cell Vacuole • Large, central vacuole • Stores water and substances needed for photosynthesis • Enzymes to recycle molecules (no lysosomes in plant cells)

  44. LE 4-12a Nucleus Chloroplast Central vacuole Colorized TEM 8,700 

  45. Contractile Vacuole • In some one-celled organisms that live in fresh water • Water enters cell from environment • Vacuole pumps out excess water • Keeps homeostasis

  46. LE 4-12b Nucleus LM 650 Contractile vacuoles

  47. Review Membrane Organelles • 4.13 A review of the endomembrane system • The various organelles of the endomembrane system are interconnected structurally and functionally • ER is in direct contact with nuclear membrane • Membrane vesicles transport products from ER to Golgi body, and from Golgi to cell surface Animation: Endomembrane System

  48. LE 4-13 Transport vesicle from Golgi to plasma membrane Transport vesicle from ER to Golgi Rough ER Plasma membrane Nucleus Vacuole Lysosome Nuclear envelope Golgi apparatus Smooth ER

  49. Organelles that capture and release energy 4.14 Chloroplasts –site for photosynthesis Chlorophyll pigment in membrane absorbs sunlight Convert solar energy into chemical energy of food Plants Algae

More Related