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115 Cards in this Set
- Front
- Back
The null model for population genetics is a) Newton's first law. b) the competitive exclusion model c) cell theory. d) the endosymbiosis theory. e) the Hardy-Weinberg model. |
e) the Hardy-Weinberg model |
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Consider a diploid population in which a single locus has only two alleles, A1 and A2, whose respective allele frequencies equal p and q. The summation of p+q would equal: a) 0.25 b) 0.5 c) 1 d) 1.5 e) 2 |
c) 1 |
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The selection coefficient describes a) the value b) how many individuals survive to reproduction c) the fitness difference between one genotype and an alternative genotype d) the change in allele frequencies due to direct selection. e) the degree of dominance of one allele relative to an alternative allele. |
c) the fitness difference between one genotype and an alternative genotype |
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At an underdominant locus, how will allele frequencies change through time? a) The homozygote with the greatest fitness advantage will have its allele fixed. b) A balance polymorphism of both alleles will be maintained at a stable equilibrium. c) The homozygote with the lowest fitness advantage will have its allele lost. d) One or the other allele will be lost depending on their initial frequencies. e) Both alleles will be lost |
d) One or the other allele will be lost depending on their initial frequenicies |
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Balancing selection |
Natural selection that leads to an intermediate phenotype or to a stable equilibrium in which more than one allele is present. |
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Balanced polymorphism |
A stable equilibrium in which more than one allele is present at a locus. |
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Inbreeding depression is caused by a) a reduction in fitness caused by deleterious recessives b) random mating c) mutation-selection balance d) A and B e) All of the above |
a) a reduction in fitness caused by deleterious recessives |
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Two gene copies are identical by descent if a) two individuals have the same parents b) one allele mutates to a second allele c) selfing occurs d) they are both inherited from the same gene copy in a recent common ancestor. e) balancing selection maintains two or more alleles |
d) they are both inherited from the same gene copy in a recent common ancestor |
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Population bottlenecks occur when a) a large number of genetically diverse individuals found a new population b) population size dramatically increases c) a consistently large population experiences a brief period of small size d) drift in consistently small populations become fixed for a single allele. e) inbreeding is high |
c) a consistently large population experiences a brief period of small size |
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A founder event changes allele frequencies because a) only a subset of genes in the original population are observed in the founder b) of random sampling of alleles from the original population c) of the coalescent process d) A and B e) All of the above |
d) A and B |
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The neutral theory of molecular variation posits that most a) mutations are neutral b) substitutions are neutral c) mutations are deleterious d) B and C e) All of the above |
b) substitutions are neutral |
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Which of the following mutations to a codon is most likely to be selectively neutral? a) UUG (Leu) -> CUG (Leu) b) AUA (lle) -> AUG (Met) c) AAC (Asn) -> AAA (Lys) d) UGC (Cys) -> UGA (Stop) e) AGC (Ser) -> AGA (Arg) |
a) UUG (Leu) -> CUG (Leu) |
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A haplotype is a) all of the alleles at a single locus b) a product of epistasis c) a set of alleles at different loci along a chromosome d) all of the alleles in a population e) none of the above |
c) a set of alleles at a different loci along a chromosome |
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A bacteriophage was the first organism to have its genome sequenced. Sequencing of this genome was facilitated by a) its complex genome b) its short genome c) previous studies of bacterial genomes d) A and C e) All of the above |
b) its short genome
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Eukaryotic genome size is a) tightly correlated with organismal complexity b) not well correlated with organismal complexity c) largest in humans d) typically smaller than prokaryotic genome sixe e) approximately the same in all eukaryotes |
b) not well correlated with organismal complexity |
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The C-value paradox is a) the lack of correlation between genome size with organismal complexity b) resolved by the identification of noncoding DNA c) resolved by the discovery of linkage disequilibrium d) A and B e) All of the above |
d) A and B
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Factors that contribute to overall genome sice include a) small genetic elements capable of self-catalyzing their movement b) selection on cell size c) selection on replication speed d) A and B e) All of the above |
e) All of the above |
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The nematode, C. elegans, and humans have nearly identical numbers of protein coding genes, yethumans have much more complex organismal features. This is an example of a) the C-value paradox. b) the G-value paradox. c) cell size paradox. d) linkage disequilibrium. e) None of the above |
b) the G-value paradox |
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LUCA (last universal common ancestor) |
The population of organisms at the base of the tree of life. All living things today descended from this one lineage
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Which of the following was not a source of molecules in the prebiotic soup? a) Meteorites b) Comets c) Prebiotic soup reactions d) DNA |
d) DNA |
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Why is DNA favored over RNA as genetic material? a) DNA is more stable and thus is a more efficient transmission system b) DNA can self-replicate c) DNA makes chromosomes d) DNA mutates more readily, with a weaker repair machinery e) DNA has a more limited information storage capacity |
a) DNA is more stable and thus is a more efficient transmission system |
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The two major cell types are a) archaea and bacteria b) Archaea and prokaryotes c) prokaryotes and eukaryotes d) eukaryotes and archaea e) eukaryotes and bacteria |
c) prokaryotes and eukaryotes |
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Which if the following statements regarding complexity is true? a) evolution always progresses toward complexity b) complexity, once gained, cannot be lost c) modern bacteria and archaea are more complex than ancestral forms d) complexity can be lost |
d) complexity can be lost |
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The cell nucleus likely originated from a(n) a) mitochondrion b) archaeal cell c) bacterium d) eukaryote |
b) archaeal cell |
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List five assumptions of the Hardy-Weinberg equilibrium. |
1) No selection 2) random mating 3) no mutation or migration 4) infinite population size 5) non-overlapping generations 6) sexual, diploid organisms |
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What is the term for the condition in which the heterozygote is more fit than either homozygote? |
Overdominance or heterozygote advantage |
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After one generation of inbreeding, one would expect to see a(n) ___ in heterozygotes but no change in ___ frequencies. |
decrease, allele |
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What are transcription factors and how do they address the G-value paradox? |
Transcriptionfactors are proteins that bind to and regulate DNA expression. By manipulating the expression of genes,transcription factors can increase the complexity of a genome’s regulatorynetwork and the organisms phenotypic complexity.
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Describe a haplotype block. |
Ahaplotype block is a region of a chromosome in which there is little geneticdiversity, recombination is rare, and linkage disequilibrium is high. |
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associative mating |
A mating pattern in which individuals with similar phenotypes or genotypes mate with one another |
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balanced polymorphism |
A stable equilibrium in which more than one allele is present at a locus
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balancing selection |
Natural selection that leads to an intermediate phenotype or to a stable equilibrium in which more than one allele is present
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directional selection |
A process of selection in which selection drives phenotype in a single direction, or in which selection drives allele frequencies in a single direction toward fixation of a favored allele.
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disassortative mating |
A mating pattern in which individuals with dissimilar phenotypes or genotypes mate with one another
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fecundity |
A measure of the ability to produce offspring
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fixation |
In population genetics, an allele is said to go to fixation in a population when it replaces all alternative alleles at the same locus-that is, when its frequency reaches 1
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frequency-dependent selection |
A form of selection in which the fitness associated with a trait or genotype is dependent upon the frequency of that trait or genotype in a population
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frequency-independent selection |
A form of selection in which the fitness associated with a trait is not directly dependent upon the frequency of that trait in a population
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Hardy-Weinberg equilibrium |
Given a set of allele frequencies, the expected set of genotype that will be observed under the Hardy-Weinberg model |
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Hardy-Weinberg model |
A null model for how genotype frequencies relate to allele frequencies in large populations and how they change over time in the absence of these evolutionary processes: natural selection, mutation, migration, assortative mating, and genetic drift.
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heterozygote advantage |
A form of frequency-independent selection in which heterozygote genotypes have higher fitness than the corresponding homozygote genotypes
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identical by decent |
When two or more gene copies are identical because of shared descent through a recent common ancestor
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inbreeding |
Mating with genetic relatives
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inbreeding depression |
A decrease in fitness that results from individuals mating with genetic relatives
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mutation-selection balance |
The hypothesis that senecence occurs because natural selection is not strong enough to purge deleterious mutations associated with traits that are expressed only late in life
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overdominance |
A form of frequency-independent selection in which heterozygote genotypes have higher fitness than the corresponding homozygote genotypes |
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population genetics |
A subdiscipline in evolutionary biology that investigates how allele frequencies and genotype frequencies change over time |
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selection coefficient |
A measure of the strength of natural selection for or against a specific phenotype or genotype
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underdominance |
A form of frequency-independent selection in which the heterozygote genotype has a lower fitness than either corresponding homozygote genotype
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Wright's F-statistic |
A statistical measure of the degree of homozygosity in a population |
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Coalescent point |
The point on a gene tree that delineates the gene copy that is the most recent common ancestor of the genes being studied in a population |
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coalescent theory |
A theory developed to study the gene-genealogical relationships in a population by tracing the ancestry of gene copies backward from the present through a finite population |
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effective population size |
The size of an idealized population (no migration, mutation, assortative mating, or natural selection) that loses genetic variation due to genetic drift at the same rate as the population under study
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expected heterozygosity |
Denoted He, this is the fraction of heterozygotes expected under the Hardy-Weinberg model, given the allele frequencies in the population
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founder effect |
A change in allele frequencies that results from sampling effects that occur when a small number of individuals derived from a large population initially colonize a new area and found a new population
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genetic drift |
Random fluctuation in allele frequencies over time due to sampling effects in finite populations
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molecular clock |
A technique for assigning relative or absolute age based on genetic data. In their simplest form, molecular clock methods assume that substitutions at neutral loci occur in clock-like fashion, and so researchers use genetic distances between populations to estimate the time since divergence
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nearly neutral theory |
The hypothesis that most substitutions, if not strictly neutral, are only mildly deleterious
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neutral theory |
The hypothesis that at the molecular level of DNA sequence or amino acid sequence, most of the variation present within a population and most substitutional differences between populations are selectively neutral
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nonsynonymous mutation |
A mutation in a gene that changes the amino acid sequence of the protein that gene encodes
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observed heterozygosity |
The fraction of individuals in the population that are heterozgous at a given locus
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population bottleneck |
A brief period of small population size. Population bottlenecks reduce genetic diversity and can accelerate changes in allele frequencies due to genetic drift
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pseudogene |
A nonfunctional and typically untranslated segment of DNA that arises from a previously functional gene
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selectively neutral |
Alternative alleles are selectively neutral when there is no fitness difference between them
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substitutions |
The process in which a new allele arises by mutation and is subsequently fixed in a population
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Wright-Fisher model |
A population genetic model of evolutionary change in small populations with nonoverlapping generations |
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adaptive landscape |
A heuristic representation of fitness as a function of genotype or phenotype. Adaptive landscapes are commonly used by biologists to envision the course of evolutionary change. Also known as fitness landscapes |
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additive genetic effects |
Genetic contributions to phenotype for a polygenetic trait, in which the effects of each allele simple sum to together to determine phenotype |
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background selection |
A process by which neutral or beneficial alleles are lost because they are physically linked to nearby deleterious alleles. Background selection decreases genetic variation relative to what would be expected in a neutral model
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breeder's equation |
The equation R=(h^2)s, relating the selection response R to the selection differential S and the narrow-sense heritability h^2
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broad-sense heritability |
(H^2) The fraction of the phenotypical variance that can be attributed to genetic causes and thus is potentially heritable |
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clonal interference |
An overall reduction in the rate at which beneficial alleles are fixed in asexual populations due to the competition amoung alternative beneficial mutations
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coefficient of linkage disequiliribum |
A measue of nonrandom association between alleles at two different loci. The coefficient of linkage disequilibrium D between two loci is defined as the difference between the actual frequency of a haplotype and the expected frequency of that haplotype if there were no association between alleles at one locus and alleles at the other locus
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coupling |
Linkage disequilibrium in which the coefficient of linkage disequilibrium D is positive
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dominance effects |
Interactions between two alleles at the same locus in determining phenotype
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epistasis |
The phenomenon in which alleles at two or more loci interact in nonadditive ways to determine phenotype
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fitness peaks |
Combinations of trait associated with the greatest fitness values on an adaptive landscape
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fitness valleys |
Combinations of traits associated with lower fitness values on an adaptive landscape |
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genetic hitchhiking |
THe process by which a neutral or even disadvantageous allele is able to "ride along" with a nearby favorable allele to which it is physically linked, and thus increase in frequency
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genotype space |
A conceptual model in which similar genotypes occupy nearby points on a plane. Adaptive landscapes are often illustrated in genotype space
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haplotype |
a set of alleles, one at each locus
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linkage disequilibrium |
The presence of statistical associations between alleles at different loci
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narrow-sense heritability |
The fraction of the total phenotypic variation that is due to additive genetic variation and this is readily accessible to natural selection
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periodic selection |
A process in which a series of clones carrying beneficial mutations successively go to fixation in an asexual population
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phenotype space |
A conceptual model in which similar phenotypes occupy nearby points on a plane. Adaptive landscapes are often illustrated in phenotype space.
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physical linkage |
The occurrence of two or more loci on the same chromosome. Physical linkage causes alleles at linked loci to segregate together (in the absense of recombination) into the gametes
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polygenic |
Traits that are affected by many genes simultaneously
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QTL mapping |
A technique for identifying the regions of the genome in which quantitative trait loci occur
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quantitative genetics |
A mathematical approach to to the population genetic study of continuously varying traits
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quantitative trait loci (QTLs) |
Loci responsible for quantitative-that is, continuously carrying- traits
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realized heritabilities |
Narrow-sense heritability values estimated by using values of the selection differential and selection response in the breeder's equation
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repulsion |
Linkage disequilibrium in which the coeffeicient of linkage disequilibrium D is negative
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selection differential |
In quantitative genetics, the difference between the mean trait value of the individuals who reproduce and the mean trait value of all individuals
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selection response |
In quantitative genetics, the difference between the mean trait value of the offspring population and the mean trait value of the parental population |
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selective sweep |
A phenomenon in which a selected allele goes to fixation, carrying with it alleles at tighty linked loci
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centromere drive |
Selection at the level of the chromosome that favors mutations to centromeres that increase their chance of segregating to oocyte instead of to the polar bodies
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codon usage bias |
A bias in which certain codons occur more frequently than others that specify the same amino acid
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conservative transposons |
A transposable element that excises itself and moves to a new location while leaving the original copy in place
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C-value paradox |
The observation that differences in genome size measured in base pairs do not correlate with the number of protein-coding genes that an organism has, nor with its phenotypic complexity
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evolutionary genomics |
The study of how the composition and structure of genomes have evolved and are evolving
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GC content |
The fraction of nucleotides in a gene, chromosomes, or genome that are G or C rather that A or T
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GC skew |
A measure of whether G nucleotides or C nucleotides are overrepresented on either the leading or lagging strand of the chromosome/ Typically measures as the (G-C)/(G+C) ratio of nucleotides along one strand of the chromosome
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G-value paradox |
The observation that despite seemingly large differences in organismal complexity, multicellular eukaryotes tend to have very similar numbers of protein-coding genes
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isochores |
Extended stretches on chromosomes that have similar GC content |
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LINEs |
Long interspersed Elements. A common clas of transposable elements, these autonomous transposons make up approx 17% of the human genome |
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nonconservative transposons |
A transposable element that creates a duplicate copy of itself to be inserted elsewhere in the genome rather that excising its self and moving to a new location |
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SINEs |
Short interspersed elements. A common class of transposable elements in humans, these non-autonomous transposons are incapable of independent replication but rather rely on genes encoded by autonomous transposons elsewhere in the genome |
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transcription factors |
Proteins that bind to DNA and influence gene expression
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transposable elements |
A self-replicating genetic unit that can move or copy itself within a genome |
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LUCA (last universal common ancestor) |
The population of organisms at the base of the tree of life. All living things today are descended from this one lineage
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phylogenetic event horizon |
The point in the history of life beyond which phylogenetic analysis is uninformative because there are no surviving descendants from ancestors before this point
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RNA world |
A hypothetical early stage in the history of life in which RNA was the fundamental unit which life was based, fulfilling both an informational roal and a catalytic role |
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Prebiotic soup hypothesis |
The idea that the earliest life emerged in a "soup-like" liquid environment, drawing upon energy from cosmic rays, volcanic eruptions, and the Earth's own internal heat |
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ribozymes |
RNA molecules with enzymatic function
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many eyes hypothesis |
The hypothesis that group living provides an advantage in the ability to detect predators |