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Bellwork

Bellwork. Looking at the pictures below, describe why you think cell’s got their name. History of Cells. Robert Hooke observed cork cells in the 1600s Compared them to monk’s rooms at a monastery. Chapter 3. Cells and Tissues. Introduction to Cells.

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Bellwork

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  1. Bellwork • Looking at the pictures below, describe why you think cell’s got their name.

  2. History of Cells • Robert Hooke observed cork cells in the 1600s • Compared them to monk’s rooms at a monastery

  3. Chapter 3 Cells and Tissues

  4. Introduction to Cells • Cells are the building blocks of all living things • Carry out all chemical activities needed to sustain life • Adult human body has about 75 trillion cells! Only 300 billion stars in the Milky Way!

  5. Introduction to Cells • At least 260 different kinds of cells in the body • Differentiation process by which a general cell becomes a specialized cell

  6. Generalized Cell • 3 major parts: • Cell membrane (plasma membrane) • Nucleus • Cytoplasm

  7. Cell Membrane • Actively functioning outer boundary • Thin, flexible, elastic • Controls what enters and exits the cell • Made of a phospholipid bilayer: • Hydrophilic heads form surfaces • Hydrophobic tails form interior • Other materials: • Proteins • Cholesterol

  8. Cell Membrane

  9. Cell Membrane • Specializations • Microvilli – increase surface area for absorption • Membrane junctions • Tight junctions • Desmosomes • Gap junctions

  10. Nucleus • Directs activities of the cell • Contains genetic material (DNA) • 3 structures: • Nuclear membrane • Nucleolus • Chromatin

  11. Nucleus • Nuclear membrane • Barrier from cytoplasm • Contains pores to exchange materials • Nucleolus • Site where ribosomes are formed • Chromatin • DNA & protein • Condenses to chromosomes for cell division

  12. Cytoplasm • Outside the nucleus but inside the cell membrane • Cytosol – fluid portion • Organelles – structures where specific reactions or functions take place • Inclusions – non-functioning unit (Ex. Stored nutrients)

  13. Cytoplasm

  14. Discussion • Think about what you know and what we talked about regarding the cell so far… • Erythrocytes (red blood cells) have no nucleus, mitochondria or other organelles at maturity. These organelles are ejected when the RBC enters the bloodstream or shortly thereafter. Should this still be considered a cell? What will be the effect of having no nucleus? In these cells, the lack of mitochondria is an advantage. Why?

  15. Organelles • Ribosomes • Endoplasmic reticulum • Vesicles • Golgi apparatus • Mitochondria • Lysosomes • Peroxisomes • Centrosome • Cilia • Microfilaments/microtubules

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