LIFE 103 1st Edition Lecture 13 Outline of Last Lecture I Root Growth II Shoot Growth III Secondary Growth IV Tree Rings V Living Things as Machines Outline of Current Lecture II Living Things as Machines III Arabidopsis thaliana IV Production of the Plant Body V Plant Cell Expansion VI Location and Fate VII Homeotic Genes VIII ABC Model of Flower Development IX Special Features of Water X Solute Transport across Cell Membranes Current Lecture Plant Structure and Development III Resource Acquisition and Transport Living Things as Machines I II III IV Molecular biology I Gene expression i DNA transcription translation proteins II Function of proteins for making cells work Developmental biology I Molecular and cellular process by which cells differentiate and organize to form tissues and organs Physiology I Function physical chemical of tissues and organs Ecology These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute I Interactions of whole organisms with each other and their environment Arabidopis thaliana I II III IV V Model organism a species studied in exceptional detail to understand how it works Arabidopsis is easy to study small weed with short generation time very small genome First plant to have genome sequenced Study of genetic mutants helps understand how plants work I Mutants are often intentionally created II Mutants help link gene to phenotype Fig 35 24 I Quarter of the genes we have no idea what they code for Cell Division and Expansion I II Fig 35 13 meristem diagram again Looking at zone of cell division Production of the Plant Body I II III IV V The plane of cell division determines direction of growth Plane of division is determined by how microtubules associated with cytoskeleton are connected just before mitosis Molecular signals within the cell that determine its polarity and how microtubules are aligned Fig 35 25 Fig 35 26 micrographs of what s going on I Microtubules circle the cell and allow for the separation of the cells Plant Cell Expansion I II III IV V VI Microfibrils in the cell wall ring the cell Step 1 enzymes weaken connections between microfibrils Step 2 vacuoles fill with water and cells expand Direction of expansion is along cell s main axis I Rings move farther apart then new rings are added Plant cells have two boundaries on them cell membrane and cell wall Fig 35 27 Cell Differentiation Location and Fate I II III To differentiate into the correct cell type cells must get information about where they are Gradients of hormones proteins or mRNA provide this information Fig 35 31 root hairs only form from epidermal cells touching 2 cortex cells I IV Control by expression of GLABRA 2 gene when present GLABRA 2 expression prevents root hair formation Fig 35 31 Homeotic Genes I II III Homeotic genes master regulatory genes that determine the differentiation fate of groups of cells like a lightswitch I These genes code for proteins that bind to DNA and affect which genes are transcribed II Homeotic mutations can put tissues or organs in the wrong place Fig 35 33 normal Arabidopsis flower vs abnormal Arabidopis flower Fig 18 18 example of wild type vs mutant flies ABC Model of Flower Development I II III IV V 4 major flower organs outside to inside I Sepals petals stamen carpels 2 gene products A B C I Each gene product can act on two organs A and C gene products are mutually exclusive I A keeps C limited C keeps A limited Fig 35 34 a schematic diagram of the ABC hypothesis as well as theoretical mutants they created A B and C are homeotic genes Resource Acquisition and Transport Special Features of Water I II III Net dipole hydrogen s electrons drawn to large oxygen nucleus Hydrogen bonds created due to charge attractions Negative and positive charge come together and are electrostatically attracted Solute Transport across Cell Membranes I Passive transport diffusive movement of an ion along concentration and charge gradients