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Cell Theory. All living things are made of cells Cells are the basic unit of life Cells today come only from other living cells. Robert Hooke first saw cells in 1665. The Structure of a Cell. All cells have Plasma membrane Cytosol DNA Ribosomes. Two Major Types of Cells. Prokaryotic
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Cell Theory • All living things are made of cells • Cells are the basic unit of life • Cells today come only from other living cells Robert Hooke first saw cells in 1665
The Structure of a Cell • All cells have • Plasma membrane • Cytosol • DNA • Ribosomes
Two Major Types of Cells • Prokaryotic • No membrane bound organelles • Make up Domains Archaea and Eubacteria • Eukaryotic • Membrane-bound organelles • Make up Kingdoms Plantae, Animalia, Protista, and Fungi
Overview of an animal cell Cytoplasm: everything inside the cell but the nucleus
Cell size The human body has over 5 billion cells. The largest animal is the blue whale, Balaenoptera musculus. It is known to reach lengths over 100 feet (30+ meters) and weigh 120 tons.
Cell size So, why aren’t there organisms composed of one really big cell?
Surface Area and Volume • Surface area of a sphere = 4r2 • Volume of a sphere = (4/3) r3 • So as a sphere gets bigger, • its volume increases faster than its surface area
Figure 7.5 Geometric relationships explain why most cells are microscopic
Let’s look at the interior of Eukaryotic cells… • Nucleus • Ribosomes • Endomembrane System • Nuclear envelope • Endoplasmic Reticulum • Golgi Apparatus • Vesicles • Lysosomes • Vacuoles • Other organelles: mitochondria, chloroplasts, peroxisomes • Cytoskeleton
DNA RNA protein: a diagrammatic overview of information flow in a cell
In the rough ER, proteins are modified by the addition of a carbohydrate group H2N COOH Protein Now = GLYCOPROTEIN Carbohydrate group
THE SECRETORY PATHWAY: A MODEL RNA 1. Proteins are synthesized in the RER Rough ER 2. Protein exits RER in a vesicle. cis face of Golgi apparatus 3. Protein travels through the cisternae of the Golgi apparatus. 4. Protein enters a secretory vesicle that fuses with cell membrane. trans face of Golgi apparatus Plasma membrane 5. Protein is secreted from cell.
Figure 7.14 The formation and functions of lysosomes (Layer 1)
Figure 7.14 The formation and functions of lysosomes (Layer 2)
Figure 7.14 The formation and functions of lysosomes (Layer 3)
Figure 7.16 Review: relationships among organelles of the endomembrane system