1 / 35

A Tour of the Cell

A Tour of the Cell. Chapter 6. Overview: The Importance of Cells. All organisms are made of cells Cells are the basic unit of structure and function in a cell Cells come from the reproduction of preexisting cells. Microscopy. Scientists use microscopes to

mahala
Download Presentation

A Tour of the Cell

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. A Tour of the Cell Chapter 6

  2. Overview: The Importance of Cells • All organisms are made of cells • Cells are the basic unit of structure and function in a cell • Cells come from the reproduction of preexisting cells

  3. Microscopy • Scientists use microscopes to visualize cells that are to small to see with the naked eye. • Light Microscopes (LMs) - pass visible light through a specimen - magnify cellular structures with lenses

  4. Electron Microscopes • Focus a beam of electrons through a specimen or onto its surface. • Two types: 1. scanning electron microscope (SEM) 2. transmission electron microscope (TEM)

  5. Scanning Electron Microscope (SEM) • Provides for detailed study of the surface of a specimen.

  6. Transmission Electron Microscope (TEM) • Provides for detailed study of the internal ultrastructure of cells.

  7. Cell Fractionation • Takes cells apart and separates the major organelles from one another. • Done with the use of a centrifuge

  8. Two Types of Cells: • Two types of cells make up every organism 1. prokaryotic 2. eukaryotic • What do they have in common: - bounded by a plasma membrane - contain a semifluid substance called the cytosol - contain chromosomes - contain ribosomes

  9. Prokaryotic Cells: - do not contain a nucleus - have their DNA located in a region called the nucleoid • Eukaryotic Cells: - contain a true nucleus - contain membrane-bound organelles - generally quite a bit larger than prokaryotic cells

  10. Prokaryotic Cells

  11. Cell Size • The logistics of carrying out cellular metabolism sets limits on the size of cells • A smaller cell has a higher surface to volume ratio, which facilitates the exchange of materials into and out of the cell.

  12. The Plasma Membrane • Functions as a selective barrier • Allows sufficient passage of nutrients and waste

  13. Panoramic View of the Eukaryotic Cell • Eukaryotic cells have extensive and elaborately arranged internal membranes, which form organelles. • Plant and animal cells have most of the same organelles.

  14. The Nucleus • Contains most of the genes in the eukaryotic cell • The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm. • The nucleolus synthesizes ribosomal RNA and small ribosomal subunits

  15. Ribosomes • Particles made of ribosomal RNA and protein • The site of protein synthesiswhere the translation of the genetic instructions yields specific polypeptides. • Free ribosomes (cytosol) and bound ribosomes (rough ER)

  16. Endoplasmic Reticulum (ER) • Accounts for more than half the total membrane in many eukaryotic cells. • The ER membrane is continuous with the nuclear envelope • There are two distinct regions of ER: - Smooth ER (lacks ribosomes) - Rough ER (contains ribosomes)

  17. Functions of Smooth ER • Synthesizes lipids • Metabolizes carbohydrates • Stores calcium • Detoxifies poison

  18. Functions of Rough ER • Compartmentalize the cell • Produces proteins and membranes, which are distributed by transport vesicles. • Plays a role in intracellular transport

  19. The Golgi Apparatus • Receives many of the transport vesicles produced in the rough ER • Consists of flattened membranous sacs called cisternae • Functions: - synthesis and packaging of materials - production of lysososmes

  20. Golgi Apparatus

  21. Lysosomes • Membrane-enclosed sacs that contain hydrolytic enzymes • Hydrolytic enzymes are important in: - intracellular digestion - recycling of the cell’s organic materials - programmed cell death (apoptosis)

  22. Vacuoles • Membrane-bound sac that plays a role in: - intracellular digestion - release of cellular waste products • In plants, a large vacuole serves many functions: - storage of pigments/poisonous substances - role in cell growth - allows for a large surface area to volume ratio

  23. Mitochondria • Sites of cellular respiration • Structure: - double membrane that allows compartmentalization - outer membrane is smooth - inner membrane folded into cristae - cristae increase surface area for ATP production

  24. Mitochondria

  25. Chloroplasts • Found only in algae and higher plants • Site of photosynthesis • Contain chlorophylls: - responsible for green color - key light trapping molecules - predominantly chlorophyll a

  26. Chloroplasts • Structure: - thylakoids (membranous sacs) - stroma (internal fluid)

  27. Cytoskeleton • A network of fibers extending throughout the cytoplasm. • Function: - gives mechanical support to the cell and maintains its shape - provides anchorage for many organelles - involved in cell motility, which utilize motor proteins

  28. Cell Wall of Plants • An extracellular structure of plant cells that distinguishes them from animal cells • Made of cellulose fibers embedded in other polysaccharides and protein • Function: - protection - maintains its shape - prevents excess water uptake

  29. The Cell – A living unit greater than the sum of its parts • Cells rely on the integration of structures and organelles in order to function.

More Related