BIO 311D 2nd Edition Lecture 22Outline of Last Lecture I. Animal cells tissues, body plansII. Hox genesOutline of Current Lecture I. Animal Development and Hox genesII. A look at the classes of vertebratesIII. What is homeostasis?Current LectureI. Animal Development and Hox genesA. Hox genes: - Helps control the expression/formation of body forms - Multi-gene family - Expressed along the anterior-posterior axis of the embryo in the same order as their arrangement between the 3’ end and the 5’ end - If one of the genes is mutated along the way: you’ll see the lack of the structure of the gene, the spread of influence of the hox gene continues fromthe anterior to posterior end. - IClicker: the absence of gene D + gene B continues [C]- A mutation in the Ubx homeotic gene resulted in a protein that inhibits leg formation in this lineage of arthropods - Influence of hox genes: insect wing, the vertebrate of the chicken, difference between a fin and a paw- IClicker: two groups of animals that are relatively closely related but in different families (such as dogs and cats) would be expected to have:Similar hox genes but differential hox gene expression patterns B. Animal Development- Larger animals have internal surfaces for exchange of substances - Cell blood; blood external surface- Exchange surfaces are finely branched to permit maximum transport across cell membranes - Diffusion: a limiting factor - Four tissue types1) Epithelial (cells in layers on a basilar membrane; for transport, secretion and protection)2) Connective (cells in a non-cellular matrix; blood, bone, cartilage, fibrous connective) 3) Muscle (smooth, striated, cardiac)4) Nerve - Elements of the cytoskeleton holds the cell shape C. Describe some specializations (cell shape, which organelles abundant, cell-cell junctions) found in these cells- Sperm: a lot of mitochondria to produce energy for movement; flagella; haploid nucleus; membrane proteins - Small intestine transport epithelium (specialized for taking up digested foods): a lot of surface area to absorb all the food; layers; membrane proteins(transport proteins) - Pancreatic secretory epithelium (produces and secretes insulin): a lot of rough ER- Macrophage (large white blood cell; engulfs and breaks down particles): a lot of lysosomes; moving cytoskeleton, nothing anchoring; amoeba movement (no cilia or flagella)- Heart muscle (communicates immediately with neighbors, when one pulls, allmove): gap junctions, desmosomes; mitochondria for energy II. Classes of VertebratesA. Arthopods: jointed legs and exoskeleton; three classes 1) Arachnids: two body segments (head and thorax), 8 legs (spiders and scorpions)2) Crustaceans: multiple pairs of appendages, specialized for different functions (crab, shrimps)3) Insects: 6 legsB. Jawless Fishes: no jaw, they suck because they can’t chewJawsC. Cartilaginous Fishes: a cartilaginous skeleton i.e. sharks D. Bony Fishes: bony skeleton Tetrapod body form (better on land)E. Amphibia: smooth, moist skin; gas exchanges Aminiotic EggF. Reptiles: scaly skin, cannot have gas exchange over the surface of their body G. Birds: Reptilian ancestry III. HomeostasisA. The concept of homeostasis: maintaining a parameter in a steady-state condition around a set point B. Hormones,
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