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Explore the diversity of cells and their functions at the cellular level through the plasma membrane, cytoplasm, and nucleus. Learn about cell structures, transport processes, organelles, and more. Discover the intricate world of cell biology!
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Cell Diversity • Lots of shapes and sizes; we have about 200 different types of specialized cells
Typical Cell Fig. 3.1
What discipline studies cells? Cell biology (Cytology) http://www.youtube.com/watch?v=tkx14B7WFcM
What is around our cells? Our cells are surrounded by extracellular fluid frequently called interstitial fluid
Cell Organization The cell includes three basic parts: • Plasma membrane (outer covering of cell) • Cytoplasm (cytosol & organelles) • Nucleus
Plasma Membrane Functions Outer boundary; functions in: • Physical isolation • Regulates what comes in and out • Anchors cytoskeleton (think of this as scaffolding)
Cell Membrane Structures The cell membrane contains: • Two layers of phospholipids(isolate the cell from extracellular fluid) • Proteins(may attach cell membrane to other structures, recognize invaders, speed up chemical reactions, bind & transport certain substances) • Cholesterol(↑ stability of cell membrane)
Selective Permeability = not all material can enter the cell Transport processes found in cells: • PASSIVE: simple diffusion & facilitated diffusion • ACTIVE: active transport & transport in vesicles Active = requires E; from low to high concentration Passive = does not require E; from high to low concentration
Osmosis – simple diffusion of water Fig. 3.8
Facilitated diffusion or Active transport - Fig. 3.10 – 3.11 Vesicular Transport (endocytosis & exocytosis) Fig. 3.12 – 3.14
Cytoplasm 2 parts: • Cytosol= fluid portion, also called intracellular fluid; contains dissolved nutrients, ions, proteins, and waste products • Organelles = cell “organs” or functional parts
Cytoskeleton • Gives the cytoplasm strength & flexibility Microfilaments
Microvilli • ↑ the surface area for absorption of material
Centrioles • Direct the movement of chromosomes during cell division
Cilia & Flagella • Cilia beat rhythmically to move fluids across cell surface • Flagella move cells
Ribosomes • Sites of protein synthesis • Attached to ER or free in the cytosol
Endoplasmic Reticulum (ER) • Rough – contains ribosomes; chemically modifies newly made proteins and ships them to the Golgi apparatus • Smooth – no ribosomes; synthesis of lipids, detoxifies certain drugs
Golgi Apparatus • Involved in packaging of proteins and production of lysosomes
Lysosomes, Peroxisomes & Proteasomes • Vesicles filled with digestive enzymes • Lysosomes recycle worn out cell structures • Peroxisomesneutralize toxins such as alcohol and hydrogen peroxide (abundant in liver) • Proteasomesdestroy unneeded and damaged proteins
Lysosomes & Peroxisomes Blue arrows = peroxisomes Red arrow = lysosome
Mitochondria • Produce adenosine triphosphate (ATP) = our energy currency
Nucleus • Control center of cell • Contains DNA needed for synthesis of 100,000 different proteins Red blood cells of humans do not have a nucleus; Skeletal muscle cells have multiple nuclei