Principles of Life, Ch. 15

Substitution rates

________ are higher at nucleotide positions that do not change the amino acid being expressed.

Speciation

________ is what leads to the branching events on the tree of life, and is the process that results in the millions of species that constitute biodiversity.

Hybridization

________ leads to the exchange of many genes among recently separated lineages of plants.

Hox genes

________ determine what organ will be made at a given location.

Pair rule genes

________ divide the embryo into units of two segments each.

acid position

If a given amino ________ is under purifying selection, then the observed rate of synonymous substitutions is expected to be much higher than the rate of nonsynonymous substitutions in the corresponding sequences.

Nonsynonymous

________ are likely to be deletrious.

small populations

In species with ________, the effects of genetic drift can overwhelm selection against noncoding sequences that have small deleterious consequences.

Maternal effect genes

________ set up the major axes (anterior- posterior and dorsal- ventral) of the embryo.

homeodomain

The ________ recognizes and binds to a specific DNA sequence in the promoters of its target genes,"turning on "the formation of specific structures.

Hox genes

________ encode a family of transcription factors that are expressed in different combinations along the length of the embryo, and help determine cell fates within each segment.

Synonymous Substitution

A change of one nucleotide in a sequence to another when that change does not affect the amino acid specified; aka silent

NonSynonymous Substitution

A change in a gene from one nucleotide to another that changes the amino acid specified by the corresponding codon; missense & nonsense are included

Pseudogenes

A DNA segment that is homologous to a functional gene but is not expressed because of changes to its sequence or changes to its location in the genome

Neutral Theory

A view of molecular evolution that postulates that most mutations do not affect the amino acid being coded for, and that such mutations accumulate in a population at rates driven by genetic drift and mutation rates

Positive selection

Natural selection that acts to establish a trait that enhances survival in a population

Purifying selection

The elimination by natural selection of detrimental characters from a population

Convergent evolution

Independent changes to the same state or trait in two or more groups of organisms

Mullers Ratchet

The accumulation-"ratcheting up"-of deleterious mutations in the nonrecombining genomes of asexual species

Lateral gene transfer

The transfer of individual genes, organelles, or fragments of genomes from one species to another, common among bacteria and archaea

Gene duplication

A way that genomes can acquire new functions

Morphogens

A diffusible substance whose concentration gradient determines a developmental pattern in animals and plants

Homoeotic mutations

Mutation in a homeotic gene that results in the formation of a different organ than that normally made by a region of the embryo

Homeobox

A 180-base-pair segment of DNA found in certain homeotic genes; regulates the expression of other genes and thus controls large-scale developmental processes

Homeodomain

A 60-amino acid sequence within the homeobox that regulates the expression of other genes and through this regulation controls large-scale developmental processes

Homologous

In evolutionary biology, one of two or more features in different species that are similar by reason of descent from a common ancestor

Genetic toolkit

A set of developmental genes and proteins that is common to most animals and is hypothesized to be responsible for the evolution of their differing developmental pathways

Genetic switches

Mechanisms that control how the genetic toolkit is used, such as promoters and the transcription factors that bind them; The signal cascades that converge on and operate these switches determine when and where genes will be turned on and off

Heterometry

Alteration in the level of gene expression, and thus in the amount of protein produced, during development, contributing to the evolution of different phenotypes in the adult

Heterochrony

Alteration in the timing of developmental events, leading to different results in the adult organism

Heterotopy

Spatial differences in gene expression during development, controlled by developmental regulatory genes and contributing to the evolution of distinctive adult phenotypes

In Vitro Evolution

A method based on natural molecular evolution that uses artificial selection in the laboratory to rapidly produce molecules with novel enzymatic and binding functions

Heterometry

________: Alteration in the level of gene expression, and thus in the amount of protein produced, during development, contributing to the evolution of different phenotypes in the adult.

Pseudogenes

________: A DNA segment that is homologous to a functional gene but is not expressed because of changes to its sequence or changes to its location in the genome.

Homeodomain

________: A 60- amino acid sequence within the homeobox that regulates the expression of other genes and through this regulation controls large- scale developmental processes.

Morphogens

________: A diffusible substance whose concentration gradient determines a developmental pattern in animals and plants.

Convergent evolution

________: Independent changes to the same state or trait in two or more groups of organisms.

Homeobox

________: A 180- base- pair segment of DNA found in certain homeotic genes; regulates the expression of other genes and thus controls large- scale developmental processes.

evolutionary biology

Homologous: In ________, one of two or more features in different species that are similar by reason of descent from a common ancestor.

Synonymous Substitution

________: A change of one nucleotide in a sequence to another when that change does not affect the amino acid specified; aka silent.

Heterotopy

________: Spatial differences in gene expression during development, controlled by developmental regulatory genes and contributing to the evolution of distinctive adult phenotypes.

Heterochrony

________: Alteration in the timing of developmental events, leading to different results in the adult organism.

Genetic toolkit

________: A set of developmental genes and proteins that is common to most animals and is hypothesized to be responsible for the evolution of their differing developmental pathways.

Mullers Ratchet

________: The accumulation "- ratcheting up- "of deleterious mutations in the nonrecombining genomes of asexual species.

Neutral Theory

________: A view of molecular evolution that postulates that most mutations do not affect the amino acid being coded for, and that such mutations accumulate in a population at rates driven by genetic drift and mutation rates.

Vitro Evolution

In ________: A method based on natural molecular evolution that uses artificial selection in the laboratory to rapidly produce molecules with novel enzymatic and binding functions.

natural selection

Purifying selection: The elimination by ________ of detrimental characters from a population.

NonSynonymous Substitution

________: A change in a gene from one nucleotide to another that changes the amino acid specified by the corresponding codon; missense & nonsense are included.