Chapter 3. Cell Structure and Function The cell theory...
Transcript of Chapter 3. Cell Structure and Function The cell theory...
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Chapter 3. Cell Structure and Function Cells – the basic units of life.
The cell theory – How do we know about cells? Light microscopes –
Transmission electron microscopes –
Why are cells so small? Surface area to volume ratio.
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Most of what is known about cell structure has been learned using electron microscopes and chemical analysis. The typical animal (human) cell. [Figure 3.4]
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Basic cell types: Prokaryotic –
Eukaryotic – The evolution of the eukaryotic cell. [Figure 3.4]
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Getting into and out of the cell. The plasma (cell) membrane – a dynamic structure. [Figure 3.6]
Major membrane components. Protein + phospholipids. Mechanisms of movement into and out of cells. Diffusion. [Figure 3.8]
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Osmosis. A diffusion of water across a semipermeable membrane.
Isotonic, hypotonic, and hypertonic solutions. [Figure 3.9]
Facilitated transport (diffusion). [Figure 3.10]
Particles diffuse through protein carriers in a membrane.
All forms of diffusion are passive.
Active transport. [Figure 3.11]
Energy (supplied by ATP is required to move particles against a concentration gradient.
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Endocytosis and exocytosis. [Figure 3.12] An active (energy requiring) movement of “large” materials into or out of a cell.
Cellular metabolism.
Metabolism = the sum of all chemical processes occurring in a cell or an organism.
Metabolic processes are controlled and regulated by enzymes.
Most metabolic processes involve groups of enzymes – enzyme systems.
Model of how enzymes work. [Figure 3.17]
Characteristics of enzymes:
Enzymes are proteins. Enzymes are very specific.
Enzymes make it easier (less energy is required) for reactions to occur. Enzymes can be denatured. Most enzyme names end in -ase.
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Cellular respiration. The function of cellular
respiration is to produce ATP.
Aerobic respiration – Oxygen is required.
Most of the reactions associated with aerobic respiration take place in the mitochondria.
C6H12O6 + O2 + ADP + Pi* CO2 + H2O + ATP
Anaerobic respiration (fermentation) in muscle cells. Glucose + ADP + Pi Lactic acid + ATP * Pi. This symbol represents an inorganic phosphate group ultimately derived from phosphoric acid
(H3PO4 ).