Biol 118 1st Edition Lecture 20 Outline of Last Lecture I Chapter 20 a Introduction to Genetic Engineering b Engineering a Safe Supply of Growth Hormone c Using Reverse Transcriptase to Produce cDNAs d Using Plasmids in Cloning e Cutting Pasting DNA f The Importance of the Creation of Sticky Ends g Transformation h Producing a cDNA Library i Screening a DNA Library j Mass Producing Growth Hormone k Ethical Concerns Over Recombinant Growth Hormone l The Polymerase Chain Reaction m Requirements of PCR n The Steps of Polymerase Chain Reaction o Dideoxy DNA Sequencing p The Potential of Gene Therapy q Introducing Novel Alleles Into Human Cells r Ethical Concerns Over Gene Therapy II Chapter 21 a Genome b Whole Genome Sequencing c How Are Complete Genomes Sequenced d Shotgun Sequencing Process e The Role of Next Generation Sequencing Strategies f The Natural History of Prokaryotic Genomes g Lateral Gene Transfer h Evidence for Lateral Gene Transfer i How Does Lateral Gene Transfer Occur j Eukaryotic Genomes k How Do Transposable Elements Work l Repeated Sequences m DNA Fingerprinting Outline of Current Lecture 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 Shared Developmental Processes II Genetic Equivalence Differential Gene Expression III Regulatory Genes IV Segmentation Genes V Regulatory Cascade VI Conservation of Hox Gene Function Current Lecture Shared Developmental Processes Cell Division proliferation o Cells divide by mitosis cytokinesis timing location amount of cell division are regulated o Most cells stop proliferating at maturity o Some specialized undifferentiated cells continue to proliferate throughout organism s life Plants meristems Can give rise to various structures that develop throughout life Animals stem cells Retain the ability to divide and give rise to an array of specialized cell Cell cell interactions o Signals produced by cells influence neighbors to divide die move or differentiate o Change patterns of gene expression Cell differentiation o Undifferentiated cells specialize at specific times places in a stepwise fashion o Cells are initially committed to a specific developmental pathway later become differentiated o Many plant cells are capable of de differentiating even after they have specialized Animal cells can de differentiate in cloning experiments Cell movement expansion o Cells can move past one another within a block of animal cells causing drastic shape change in embryo o Cells can break away from a block of animal cells migrate to new location o Plant cells can regulate the plane of cell division expand in specific directions causing dramatic changes in shape types Do not move but can change orientation of cell division o Gastrulation animal cells in different parts of an early embryo rearrange themselves into 3 distinctive types of embryonic tissue that later form specific organs Programmed cell death apoptosis o Timing location amount of cell death are regulated Too much or too little can lead to disease or deformation Genetic Equivalence Differential Gene Expression Differential gene expression Expression of different genes in different cell types o Key to cell differentiation during development Plant cells can de differentiate to form other plant parts o Each cell must contain the genes required by all different types of plant cells Research on cloning shows that cellular differentiation does not involve changes in the genetic makeup of cells but rather results from differential gene expression Genes can be regulated at multiple levels transcription RNA processing translation post translation o Transcription is the fundamental level of control in differential gene expression during development controlled by regulatory transcription factors Fate of a cell depends on o Timing current stage of development in the organism Determined by chemical signals o Spatial location where it is in the body of the organism Determined by 3 major body axes Anterior head posterior tail Ventral belly dorsal back Left right Pattern formation series of event that determine the spatial organization of an embryo Morphogens Certain early signal that activate a network of genes that sends signals with more specific information about the spatial location of cells Regulatory Genes Bicoid Most dramatic mutation in drosophila structures on anterior replaced with posterior structures two tailed o Tells cells where they are located along the anterior posterior body axis o In situ hybridization process to determine the location of bicoid mRNA in the egg High localized in the anterior of the egg steep concentration gradient from anterior to posterior end o Regulatory transcription factor and turns on genes responsible for forming anterior structures Auxin Enters cells and triggers the production of transcription factors that affect differentiation o Works by forming concentration gradients Segmentation Genes Segment Distinct region of an animal body that contains a distinct set of structures and is repeated along its length Segmentation genes organize cell tissues into distinct segments 3 classes o Gap Genes define the general position of segments in the anterior middle or posterior of the body o Pair rule genes demarcate the boundaries of individual segments o Segment polarity genes Delineate boundaries within individual segments Hox genes identify each segment s structural role o Trigger the development of structures that are appropriate to each type of segment by regulatory transcription factors o Expressed in a distinctive pattern along anterior posterior axis after segments are established o Homeosis occurs when cells get incorrect information about where they are in the body Regulatory Cascade Interactions among bicoid segmentation genes form regulatory cascade o Morphogens o Gap Genes o Pair rule genes o Segment polarity genes o Hox genes o Effector Genes Each level provides a more specific level of information about where a cell is Conservation of Hox Gene Function Hox genes occurs in every animal o Varies in number but chromosomal organization is similar Mutations in Hox genes of many different animals result in defects in pattern fprmation o Hoxb6 from mice inserted into fruit flies had similar defects
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