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Bio Chapter 18 Terms ;)

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clairebear2018's version from 2018-04-12 04:32

Section 1

Question Answer
The switch is a segment of DNA called an ______, usually positioned within the promoteroperator
Operonthe entire stretch of DNA that includes the operator, the promoter, and the genes that they control
The operon can be switched off by a proteinrepressor
The repressor is the product of a separate ______, located some distance from the operon itselfregulatory gene
Corepressora molecule that cooperates with a repressor protein to switch an operon off
Repressible Operonone that is usually on; binding of a repressor to the operator shuts off transcription
Inducible Operonone that isusually off; a molecule called an inducer inactivates the repressor and turns on transcription
Inducerinactivates the repressor to turn the inducible operon on
Some operons are also subject to positive control through a stimulatory protein, an ______ of transcriptionactivator
When glucose (a preferred food source of E. coli) is scarce, CRP is activated by binding with cyclic AMP (cAMP)
Differences between cell types result from ______, the expression of different genes by cells with the same genome differential gene expression
DNA Methylationthe addition of methyl groups to certain bases in DNA, is associated with reduced transcription in some species
Associated with most eukaryotic genes are multiple ______, segments of noncoding DNA that serve as binding sites for transcription factors that help regulate transcriptioncontrol elements
Distal control elements, groupings of which are called _____, may be far away from a gene or even located in an intronenchancers
Activator a protein that binds to an enhancer and stimulates transcription of a gene
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Section 2

Question Answer
Some transcription factors function as ______, inhibiting expression of a particular gene in several different waysrepressors
Alternative RNA Splicingdifferent mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
MicroRNAs (miRNAs) small, single-stranded RNA molecules that can bind complementary sequences in mRNA
Small interfering RNAs (siRNAs) are similar to miRNAs in size and function
The blocking of gene expression by siRNAs is called RNA interference (RNAi)
Cell _______ is the process by which cells become specialized in structure and functiondifferentiation
The physical processes that give an organism its shape constitute morphogenesis
Cytoplasmic determinants are maternal substances in the egg that influence early development
In the process called ______, signal molecules from embryonic cells cause changes in nearby target cellsinduction
Pattern Formationthe development of a spatial organization of tissues and organs
Positional Informationthe molecular cues that control pattern formation, tells a cell its location relative to the body axes and to neighboring cells
Lewis discovered _____, which control pattern formation in the late embryo, larva, and adult stageshemotic genes
Maternal Effect Genesencode cytoplasmic determinants that initially establish the axes of the body of Drosophila
One maternal effect gene, the _____ gene, affects the front half of the bodybicoid
This hypothesis is an example of the morphogen gradient hypothesis, in which gradients of substances called ______ establish an embryo’s axes and other features of its formmorphogens
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