Lecture%209

Lecture%209 - BILD1 The Cell Prof. Lisa M. Boulanger...

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1 02/08/07 BILD1 - Lecture 9 1 BILD1 The Cell Prof. Lisa M. Boulanger 02/08/07 BILD1 - Lecture 9 2 Problem Set 4 posted tomorrow, discussed next week Regrade requests must be submitted in writing, on paper by Feb. 15 th Whole exam will be regraded! Simple addition errors will NOT be fully regraded—just corrected 02/08/07 BILD1 - Lecture 9 3 Plants: cell walls, plasmodesmata Animals: extracellular matrix (ECM), tight junctions, gap junctions, desmosomes Plasma membrane is fluid phospholipid bilayer (saturation affects fluidity) Membrane proteins function in transport, enzymatic activity, signal transduction, cell recognition, intercellular joining, cytoskeleton/ECM link Highlights from previous lecture: 02/08/07 BILD1 - Lecture 9 4 Highlights from previous lecture: Membranes are selectively permeable small, polar can diffuse down concentration gradient unaided Osmosis causes water to enter or leave cell depending on extracellular tonicity Hypertonic = more solutes than inside cell, water exits cell Hypotonic = less solutes, water enters cell Isotonic = same, no movement Passive transport down gradient via channels, carriers Active transport against gradient via pumps, cotransport Exocytosis and endocytosis 02/08/07 BILD1 - Lecture 9 5 THIS LECTURE: Cell signaling and cellular communication! 02/08/07 BILD1 - Lecture 9 6 Cell-to-cell communication Is absolutely essential for multicellular organisms External signals are converted into responses within the cell
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2 02/08/07 BILD1 - Lecture 9 7 The amazing DICTYOSTELIUM! 02/08/07 BILD1 - Lecture 9 8 Signal transduction pathways Convert signals on a cell’s surface into cellular responses Are similar in microbes and mammals, suggesting an early origin Common mechanisms are used by many types of signals 02/08/07 BILD1 - Lecture 9 9 Local and Long-Distance Signaling Cells in a multicellular organism Communicate via chemical messengers 02/08/07 BILD1 - Lecture 9 10 Animal and plant cells Have cell junctions that directly connect the cytoplasm of adjacent cells Plasma membranes Plasmodesmata between plant cel s Gap junctions between animal cel s 02/08/07 BILD1 - Lecture 9 11 Cell-cell recognition In local signaling, animal cells May communicate via direct contact 02/08/07 BILD1 - Lecture 9 12 In other cases, animal cells Communicate using local regulators General paracrine signaling Specific: Synaptic signaling Local regulator dif uses through extracel ular fluid Target cel Secretory vesicle Electrical signal along nerve cel triggers release of neurotransmit er Neurotransmit er dif uses across synapse Target cel is stimulated Local paracrine signaling
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3 02/08/07 BILD1 - Lecture 9 13 In long-distance signaling Both plants and animals use hormones Hormone travels in bloodstream to target cel s Hormonal signaling Blood vessel Target cel Endocrine cel 02/08/07 BILD1 - Lecture 9 14 The Three Stages of Cell Signaling EXTRACELLULAR FLUID Receptor
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Lecture%209 - BILD1 The Cell Prof. Lisa M. Boulanger...

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