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45 Cards in this Set
- Front
- Back
Connection Between Gene Regulation and Physiology and Behavior in Primates |
- Showed that higher-status female macaque primates had stronger immune systems and genes that were expressed differently (meaning different genes were turned on and off) than lower-status female macaques - Shows that many factors, including social status can control gene expression |
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Operon Model |
- Proposed by Francois Jacob and Jacques Monod to explain regulation of gene expression in prokaryotes - ____________ is a group of structural and regulatory genes that function as a single unit - Enzymes are produced as needed |
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Promotor Operator Structural Genes |
3 Components of Operon |
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Promotor |
- DNA sequence where RNA polymerase first attaches, short segment of DNA |
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Operator |
DNA sequence where active repressor binds, short segment of DNA |
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Structural Genes |
- One to several genes coding for enzymes of a metabolic pathway - Transcribed simultaneously as a block - Long segment of DNA |
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Regulatory Gene |
- Codes for a repressor protein that controls the operon - Normally located outside the operon - Repressor protein controls whether the operon is active or not |
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- Repressor is unable to attach to the operator (expression is normally "on") - RNA polymerase binds to the promotor - Which triggers production of enzymes for synthesis |
3 things if tryptophan is absent (trp Operon) |
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- trp combines with repressor protein as its corepressor - Repressor becomes functional so blocks synthesis of enzymes in the pathway for tryptophan synthesis |
2 things if tryptophan trp Operon is present |
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- If lactose (sugar for food) is absent, repressor attaches to the operator (expression is normally "off" |
When lactose lac operon is absent |
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- Lac operon combines with repressor and renders it unable to bind with operator - RNA polymerase binds to promotor - Triggers production of 3 enzymes necessary for lactose catabolism |
If lac operon lactose is present, 3 things that happen |
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E Coli |
- Disease that preferentially breaks down glucose |
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When glucose is absent in prokaryotic regulation |
- Without ________, lac operon is maximally activated - cAMP accumulates, binds to catabolite activator protein, together binds to site near lac promotor - When bound, RNA polymerase binds better to promotor - Structural genes of lac operon are expressed more efficiently |
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Nuclear Levels - Chromatin Structure - Transcriptional Control - Posttranscriptional Control Cytoplasmic Levels - Translational Control - Posttranslational Control |
Eukaryotic Regulation there are a variety of mechanisms 5 Primary levels of control |
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Chromatin |
- Eukaryotic DNA is associated with histone proteins to make up what? |
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Nucleosomes |
DNA is wound around groups of 8 histone proteins and looks like beads on a string - What are these beads called? - Levels of chromatin packing are determined by degree of _______ coiling |
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Euchromatin Heterochromatin |
- Loosely coiled and transcriptionally active - Tightly packed and transcriptionally inactive |
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Barr Body |
- Of the two X chromosomes of the female, the tightly packed inactive X chromosome Ex: Calico Cat |
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Epigenetic inheritance |
- Refers to inheritance patterns not dependent on genes themselves and explains unusual inheritance patterns - May also play a role in growth, aging and cancer Ex: Histone modification where variations in the pattern of inheritance is not due to changes in the sequence of DNA nucleotides |
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Transcriptional Control |
- Controlled by proteins called transcription factors which help regulate transcription by assisting the binding of the RNA polymerase to the promoter - Transcriptional activator is a DNA binding protein that binds to enhancer DNA, regions of DNA where transcription factors can also bind - Always present in the cell, but most likely have to be activated before they will bind to DNA |
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Posttranscriptional Control |
- Operates on the primary mRNA transcript, where excision of introns and splicing of exons can vary - Control speed of mRNA transport out of nucleus by affecting number of transcripts arriving at rough ER, thus amount of gene product Ex: Hypothalamus and thyroid release different versions of calcitonin |
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sRNA (small RNA) |
- Noncoding transcribed DNA used to form _____ which are involved in gene regulation and function at multiple levels of gene expression - Regulate transcription and translation - Source of microRNAs (miRNA) regulating translation by causing destruction of mRNAs before they can be translated - Source of small interfering (siRNA) that form silencing complex that targets specific mRNAs for breakdown, preventing expression - Referred to as RNA interference |
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microRNA (miRNA) small-interfering RNA(siRNA) |
sRNA molecules source 2 types of RNA that help in RNA interference |
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microRNA miRNA |
- Regulates translation by causing the destruction of mRNAs before they can be translated |
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small-interfering RNA siRNA |
- Form a silencing complex that targets specific mRNAs for breakdown, preventing their expression |
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Translational Control |
- Determines the degree to which mRNA is translated into protein product - The presence of the 5' cap and length of poly A tail on 3' end of the mRNA affect whether translation occurs or how long mRNA remains active |
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Posttranslational control |
- Affects activity of protein product - Accomplished by regulating activation and degradation rate - Proteases are enzymes that break down proteins and by doing so help regulate gene expression - how long protein remains active or confined to proteasome or lysosomes to protect cell |
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Gene Mutation |
- Permanent change in the sequence of bases in DNA - Effects can range from no effect to complete inactivation of the protein - Germ-line mutations in sex cells - Somatic mutations in body cells |
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Spontaneous mutation |
- Chemical changes in DNA that lead to mispairing during replication - Movement of transposons from one chromosomal location to another - Replication Errors from DNA polymerase 1/ 1,000,000,000 |
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Induced mutations |
- Caused by mutagens such as radiation, carcinogens and organic chemicals - Environment mutagens include UV radiation and tobacco smoke |
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Point Mutation |
- Example: Base substitution which involves change in a single DNA nucleotide, changing one codon to a different codon - Effects on the protein vary from being nonfunctional, reducing it or not affecting it |
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Frameshift Mutations |
- 1 or 2 nucleotides are either inserted or deleted from DNA - Protein is always rendered nonfunctional - Results in different reading frame for the codons |
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Proto-Oncogenes |
- Stimulate cell division - Mutated versions are always active |
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Tumor Suppressor Genes |
- Inhibit cell division |
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Cancer |
- Development involves a series of accumulating mutations - Oncogenes and mutations in tumor suppressor genes lead to tumor formation - Stimulate the cell cycle uncontrollably |
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Nonfunctional Proteins Faulty Enzyme |
- If inserted into metabolic pathway, a personal may be unable to convert one molecule to another with serious consequences -Ex: Phenylketonuria: Excess buildup causes intellectual disability -Ex: Androgen insensitivity: Cells unable to respond to testosterone so female genitals and characteristics occur at puberty |
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Transcriptional Control |
- Transcription factors bind to promoters - Transcription activators bind to enhancers - Mediator proteins bind transcription activators to transcription factors - RNA polymerase begins transcribing |
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Transcription Activator Transcription Factor |
2 proteins required for transcription initiation by RNA polymerase |
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DNA repair enzymes |
- Remove damaged DNA - Seal new DNA into a preexisting DNA strand - Make new section of DNA |
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Spontaneous Mutation Causes |
- Chemical Change of a base - DNA replication - Transposon movement |
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Possible consequences of mutated DNA gene? |
- Different protein product - Different genotype - Different phenotype - Different mRNA transcript |
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Enhancer |
Region of DNA that acts as regulatory element through binding with transcription activators |
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Promoter |
Binds with transcription factors |
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Mediator Proteins |
Acts as a bridge between transcriptional factors and transcription activators |
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Transcription Factors |
- Proteins that help regulate transcription by assisting the binding of RNA polymerase to the promotor |