Lecture 3b - Organelles, mitosis, central dogma

Lecture 3b - Organelles, mitosis, central dogma - 1 Lecture...

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Unformatted text preview: 1 Lecture 3b. Anatomy of the cell organelles, cell division, and the central dogma Anatomy of the Cell Organelles Question z A red blood cell is placed in a solution and a few minutes later, the cell shrinks (crenates). What was the tonicity of the solution? Question z Celery begins to wilt after it has been in the fridge for a while. You can actually restore some of its crispness by submersing it in a solution. What kind of solution would you use? Cellular level z Cytology: structure and function of cells z Cell biology Cell Theory z Cells are smallest unit of life z All cells come from previously existing cells through cell division z Cells perform all physiological functions z Maintains homeostasis at the level of the cell which impacts tissues, organs, and systems 2 Numbers and diversity z Body contains trillions of cells z Also has thousands of different types of cells (there are hundreds of different types of neurons alone) Two general classes of cells 1. Somatic cells (diploid, 2n) two copies of each chromosome 2. Sex cells (haploid, n) one copy of each chromosome Organelles z Internal cell structures that perform specific cellular functions z Cytoplasmic organelles: z Membranous z Mitochondria, peroxisomes, lysosomes, endoplasmic reticulum, and Golgi apparatus z Nonmembranous z Cytoskeleton, centrioles, and ribosomes z Exterior: Plasma membrane Cytoplasm z Cytoplasm material between plasma membrane and the nucleus z Cytosol largely water with dissolved protein, salts, sugars, and other solutes Cytoplasm = cytosol + organelles Anatomy of a Cell 3 Nonmembranous: Cytoskeleton z The skeleton of the cell z Dynamic, elaborate series of protein rods running through the cytosol z Consists of: z Microfilaments z Intermediate filaments z Microtubules z Muscle cells contain thick filaments Microfilaments z The smallest in diameter (7nm), most fragile z Made of the protein actin and located in the periphery of the cell z Attached to the cytoplasmic side of the plasma membrane z Braces and strengthens the cell surface z Involved in cell movement and shape changes Intermediate filaments z Intermediate in size (7-11nm) z Tough, insoluble protein fibers with high tensile strength z The most durable of the cytoskeletal fibers z Several varieties exist (e.g. keratin) z Functions z Provides shape of the cell z Resist pulling forces Thick filaments z Only found in muscle cells z Made of protein myosin z Interact with actin microfilaments to cause contraction Microtubules z Largest of the fibers (25nm) z Dynamic, hollow tubes made of the spherical protein tubulin z Microtubular array of the cell is near the nucleus z Functions: z Determine the overall shape of the cell and distribution of organelles z Help move structures in the cell (like highways) z Form the spindle apparatus z Form centrioles and cilia Microtubules Figure 3.24c 4 Centrioles and Cilia are made of microtubules z Centrioles z Organize mitotic spindle during mitosis z...
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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Lecture 3b - Organelles, mitosis, central dogma - 1 Lecture...

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