Biol 118 1st Edition Lecture 20 Outline of Last Lecture I. Chapter 20a. Introduction to Genetic Engineeringb. Engineering a Safe Supply of Growth Hormonec. Using Reverse Transcriptase to Produce cDNAsd. Using Plasmids in Cloninge. Cutting & Pasting DNAf. The Importance of the Creation of Sticky Endsg. Transformationh. Producing a cDNA Library i. Screening a DNA Libraryj. Mass-Producing Growth Hormonek. Ethical Concerns Over Recombinant Growth Hormonel. The Polymerase Chain Reactionm. Requirements of PCRn. The Steps of Polymerase Chain Reactiono. Dideoxy DNA Sequencingp. The Potential of Gene Therapyq. Introducing Novel Alleles Into Human Cells r. Ethical Concerns Over Gene TherapyII. Chapter 21a. Genomeb. Whole-Genome Sequencingc. How Are Complete Genomes Sequenced?d. Shotgun Sequencing Processe. The Role of ‘Next-Generation Sequencing’ Strategiesf. The Natural History of Prokaryotic Genomesg. Lateral Gene Transferh. Evidence for Lateral Gene Transferi. How Does Lateral Gene Transfer Occur?j. Eukaryotic Genomesk. How Do Transposable Elements Work?l. Repeated Sequencesm. DNA FingerprintingOutline 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 ProcessesII. Genetic Equivalence & Differential Gene Expression III. Regulatory GenesIV. Segmentation GenesV. Regulatory CascadeVI. Conservation of Hox Gene FunctionCurrent LectureShared Developmental Processes- Cell Division (proliferation)o Cells divide by mitosis & cytokinesis; timing, location & amount of cell division are regulatedo Most cells stop proliferating at maturityo 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 types- Cell-cell interactionso Signals produced by cells influence neighbors to divide, die, move or differentiateo Change patterns of gene expression- Cell differentiationo Undifferentiated cells specialize at specific times & places in a stepwise fashiono Cells are initially committed to a specific developmental pathway & later become differentiatedo Many plant cells are capable of de-differentiating even after they have specialized Animal cells can de-differentiate in cloning experiments- Cell movement & expansiono Cells can move past one another within a block of animal cells, causing drastic shape change in embryoo Cells can break away from a block of animal cells & migrate to new locationo Plant cells can regulate the plane of cell division & expand in specific directions, causing dramatic changes in shape Do not move, but can change orientation of cell divisiono 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 deformationGenetic Equivalence & Differential Gene Expression- Differential gene expression: Expression of different genes in different cell typeso Key to cell differentiation during development- Plant cells can de-differentiate to form other plant partso 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-translationo Transcription is the fundamental level of control in differential gene expression during development controlled by regulatory transcription factors- Fate of a cell depends ono Timing (current stage of development in the organism) Determined by chemical signalso 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 cellsRegulatory 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 axiso 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 endo Regulatory transcription factor and turns on genes responsible for forming anterior structures- Auxin: Enters cells and triggers the production of transcription factors that affect differentiationo Works by forming concentration gradientsSegmentation 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 bodyo Pair-rule genes: demarcate the boundaries of individual segmentso Segment polarity genes: Delineate boundaries within individual segments- Hox genes: identify each segment’s structural roleo Trigger the development of structures that are appropriate to each type of segment by regulatory transcription factorso Expressed in a distinctive pattern along anterior-posterior axis, after segments are establishedo Homeosis: occurs when cells get incorrect information about where they are in the bodyRegulatory Cascade- Interactions among bicoid & segmentation genes form regulatory cascadeo Morphogenso Gap Geneso Pair-rule geneso Segment polarity geneso 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 animalo Varies in number, but chromosomal organization is similar- Mutations in Hox genes of many different animals result in defects in pattern fprmationo Hoxb6 from mice inserted into fruit flies had similar
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