LIFE 103 1st Edition Lecture 13Outline 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 ExpansionVI. 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 MachinesI. Molecular biology I. Gene expressioni. DNA transcription, translation  proteinsII. Function of proteins for making cells work II. Developmental biologyI. Molecular and cellular process by which cells differentiate, and organize to form tissues and organs III. PhysiologyI. Function (physical, chemical) of tissues and organs IV. EcologyThese 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. Model organism: a species studied in exceptional detail to understand how it works II. Arabidopsis is easy to study: small weed with short generation time, very small genome III. First plant to have genome sequencedIV. Study of genetic mutants helps understand how plants work I. Mutants are often intentionally createdII. Mutants help link gene to phenotype V. Fig. 35.24 I. Quarter of the genes we have no idea what they code for Cell Division and ExpansionI. Fig. 35.13 (meristem diagram again) II. Looking at zone of cell division Production of the Plant Body I. The plane of cell division determines direction of growth II. Plane of division is determined by how microtubules (associated with cytoskeleton) are connected just before mitosis III. Molecular signals within the cell that determine its polarity, and how microtubules are aligned IV. Fig. 35.25 V. Fig. 35.26 (micrographs of what’s going on) I. Microtubules circle the cell and allow for the separation of the cells Plant Cell ExpansionI. Microfibrils in the cell wall ring the cell II. Step 1: enzymes weaken connections between microfibrils III. Step 2: vacuoles fill with water, and cells expand IV. Direction of expansion is along cell’s main axis I. Rings move farther apart, then new rings are added V. Plant cells have two boundaries on them: cell membrane and cell wall VI. Fig. 35.27 Cell Differentiation: Location and Fate I. To differentiate into the correct cell type, cells must get information about where they are II. Gradients of hormones, proteins or mRNA provide this informationIII. Fig. 35.31: root hairs only form from epidermal cells touching 2 cortex cellsI. Control by expression of GLABRA-2 gene (when present, GLABRA-2 expression prevents root hair formation) IV. Fig. 35.31 Homeotic GenesI. 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 II. Fig. 35.33: normal Arabidopsis flower vs. abnormal Arabidopis flower III. Fig. 18.18: example of wild-type vs. mutant flies ABC Model of Flower Development I. 4 major flower organs (outside to inside) I. Sepals, petals, stamen, carpelsII. 2 gene products (A, B, C)I. Each gene product can act on two organsIII. A and C gene products are mutually exclusiveI. A keeps C limited; C keeps A limited IV. Fig. 35.34: a schematic diagram of the ABC hypothesis as well as theoretical mutants they created V. A, B, and C are homeotic genes Resource Acquisition and Transport Special Features of WaterI. Net dipole: hydrogen’s electrons drawn to large oxygen nucleus II. Hydrogen bonds: created due to charge attractions III. 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