Gene Expression. Chapters 11 & 12: Gene Conrtrol and DNA Technology. Cloning. Honors Biology Fig

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1 Chapters & : Conrtrol and Technology Honors Biology 0 Cloning Produced by asexual reproduction and so it is genetically identical to the parent st large cloned mammal: Dolly the sheep Animals that are endangered could be cloned to aviod extinction Disadvantages: does not increase genetic diversity, cloned animals often have health problems because of abnormal gene regulation Donor Nucleus from donor Reproductive cloning Implant blastocyst in surrogate mother Clone of donor is born Remove nucleus from egg Add somatic from adult donor Grow in culture to produce an Therapeutic early embryo cloning (blastocyst) Remove embryonic stem s from blastocyst and grow in culture Induce stem s to form specialized s. Expression expression - the process of information as it flows from genes to s Mainly control the process of transcription Organisms respond to environmental changes by controlling gene expression

2 How Expression Works Operon - group of genes controlled in bacteria Example: Lactose (lac) operon Three adjacent genes for lactose-utilization enzymes Promoters where binds Operator sequence where a can bind to block Regulatory gene - codes for a Without lactose present, the binds to the operator Lactose inactivate the (operator unblocked) OPERON Regulatory gene Promoter Operator Lactose-utilization genes Protein Active cannot attach to promoter Operon turned off (lactose absent) bound to promoter Protein Lactose Inactive Operon turned on (lactose inactivates ) Enzymes for lactose utilization. Operon Control Inducible operon (ex. lac operon) Active binds to the operator Inducer (lactose) binds to and inactivates the Repressible operon (ex. trp operon) Repressor is intially inactive Co (tryptophan) binds to and makes it active Promoter Operator Active Active Tryptophan. Inactive lac operon Lactose Inactive trp operon 6

3 X-Chromosome Inactivation Female mammals have one of their two X chromosomes inactivated randomly during embryonic development. Early embryo Two populations in adult X chromosomes Cell division and random X chromosome inactivation Active X Inactive X Orange fur Allele for orange fur Allele for black fur Inactive X Active X Black fur 7 Eukaryotic Regulation factors - promote RNA polymerase binding to the promoter Enhancers - activator s that bind to and interact with transcription factors Silencers - s that inhibit transcription Enhancers factors Bending of Activator s Other s Promoter. 8 Alternative Splicing Production of different s from the same transcript Results in production of more than one polypeptide from the same gene Exons RNA transcript RNA splicing or.6 9

4 Regulation and Development Fruit flies Orientation from head to tail Segmentation of the body Production of adult features Homeotic genes - control the anatomy and structural development Eye Antenna Head of a normal fruit fly Egg within ovarian follicle Follicle s Head Embryo Adult fly Leg Head of a developmental mutant Egg Protein signal expression Cascades of gene expression Body segments expression.0 0 Signal Transduction Signaling Signaling molecule Receptor Plasma membrane Target Relay s Converts a signal on the s surface to a signal inside the factor (activated) Nucleus New 6. Translation tic Basis of Cancer Mutations in two types of genes cause cancer Oncogenes Proto-oncogenes - promote division; will increase this activity Tumor-suppressor genes - inhibit divison; inactivate these genes and allow for uncontrolled division Hyperactive growthstimulating in normal amount Mutation within the gene Oncogene Tumor-suppressor gene Normal growthinhibiting Cell division under control Normal growthstimulating in excess Multiple copies of the gene Proto-oncogene New promoter moved to new locus, under new controls Normal growthstimulating in excess Mutated tumor-suppressor gene Defective, nonfunctioning Cell division not under control

5 tic Basis of Cancer Production of a cancer usually requires four or more somatic Activation of an oncogene increases division Inactivation of a tumorsuppressor gene causes the formation of a benign tumor Additional lead to a malignant tumor Cellular Increased changes: division Oncogene changes: activated Chromosomes mutation Normal Colon wall Growth of polyp Tumor-suppressor gene inactivated Growth of malignant tumor (carcinoma) Second tumorsuppressor gene inactivated Malignant.9 Cloning a tic engineering - manipulating genes for practical purposes cloning - leads to the production of multiple identical copies of gene-carrying piece of - formed by joining sequences from two different sources Source : gene being cloned Source : gene carrier called a vector Plasmids - small circular molecule independent of a bacterial chromosome Steps in Cloning a. Plasmid is isolated. containing the gene of interest is isolated.plasmid is treated with a restriction enzyme that cuts in one place (opens the circle). with the target gene is treated with the same enzyme and many fragments are produced.plasmid and target are mixed and associate with each other 6. molecules are produced when ligase joins the plasmid and target segments together 7. is taken up by the bacterial 8.Bacterial reproduces to form a clone of s

6 E. coli bacterium Plasmid Bacterial chromosome Isolate plasmid Isolate Cell with containing gene of interest Cut plasmid with enzyme of interest Cut s with same enzyme of interest Combine targeted fragment and plasmid plasmid bacterium 6 Add ligase, which closes the circle with covalent bonds of interest 7 Put plasmid into bacterium by transformation 8 Allow bacterium to reproduce Examples of gene use s may be inserted into other organisms 9 s or s are isolated from the cloned bacterium Harvested s Examples of may be use used directly Clone of s. 6 Restriction Enzymes Restriction enzyme cuts the into fragments Restriction enzyme recognition sequence Each enzyme binds to at a different location called a restriction site Create sticky ends Addition of a fragment from another source Two (or more) fragments stick together by base-pairing Sticky end ligase joins fragments together. ligase pastes the strands molecule 7 Products of Technology Vaccines - stimulates immune response through injection of either a from the surface of the infectious agent, a harmless version of the infectious agent, or a harmless version of the smallpox virus containing genes from other infectious agents tically modified organisms (GMOs) - organisms that contain one or more genes from another species Agrobacterium tumefaciens containing gene for desired trait Plant Ti plasmid Insertion of gene Ti plasmid into plasmid Restriction site Introduction Regeneration into plant of plant s carrying new gene Plant with new trait.8 8

7 Therapy Cloned gene (normal allele) Insert normal gene into virus Viral nucleic acid Treat diseases by supplying a functional allele Retrovirus Infect bone marrow with virus Possible procedures: Clone the functional allele and insert it into a retroviral vector and use the virus to deliver the gene to the affected type Inject s into patient Viral inserts into chromosome Bone marrow from patient Bone marrow 9 Profiling Analysis of fragments to determine whether they come from a particular individual Polymerase chain reaction (PCR) - allows for amplification (making many copies) of a segment of Gel electrophoresis - separates molecules based on size.!!!! Target sequence isolated of selected markers amplified Amplified compared Crime scene Cycle yields molecules! Heat to Cool to allow separate primers to form strands hydrogen bonds with ends of target sequences! Suspect Suspect Genomic!!!!!! Power source!!!!!! Primer polymerase adds nucleotides to the! end of each primer New Mixture of fragments of different sizes Gel Used for: Forensics Family Analysis ID of Human Remains Species ID Cycle yields molecules Cycle yields 8 molecules Longer (slower) molecules Shorter (faster) molecules Completed gel 0 Genomics Study of an organisms complete genome Allows for examination of evolutionary relationships Human Genome Project Determine the nucleotide sequence of all in the human genome Identify the location and sequence of every human gene Discovered humans have:,000 genes Only.% of codes for s, trna, or rrna 98.% of contains control regions for promotes and enhancers, unique noncoding, and repetative Chromosome Chop up with restriction enzyme fragments Sequence fragments Align fragments Reassemble full sequence.9