Bio Exam 1 Flashcards
Lamarckian Ideology
Lamarckian theory is a theory of evolution based on the principle that physical changes in organisms during their lifetime can be transmitted to their offspring
Theory of Evolution
The theory of evolution is the idea that all living things share a common ancestor and change over time due to natural selection and other factors.
Extinction
creatures that have no populations on Earth anymore
Transitional features
A trait that is intermediate between a trait observed in ancestral (older) species and the homologous trait observed in derived (younger) species.
Vestigial traits
A reduced or incompletely developed structure that has no function, or reduced function, but is clearly similar to functioning organs or structures in ancestral or closely related species
Homology
Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous
Developmental homology
A similarity in embryonic form or developmental processes that is due to inheritance from a common ancestor.
Structural homology
Similarities in adult organismal structures (e.g., limbs, flowers) that are due to inheritance from a common ancestor.
Darwin’s 4 Postulates of Natural Selection
- Individuals within population are variable
- Some of these variations are passed on to offspring
- Not all individuals produce the same number of offspring
- Individuals with certain heritable traits produce the most offspring
Evolutionary fitness
The ability of an individual to produce viable offspring relative to others of the same species.
Evolutionary adaption
Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.
Evolution
(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection, genetic drift, gene flow, and mutation. (2) Any change in the genetic characteristics of a population over time, especially a change in allele frequencies.
Trait
Any observable characteristic at any level of observation of an individual
Polymorphic trait
A trait for which more than one form of an allele commonly appears in a population
Phenotype
Physical makeup
Genotype
Genetic makeup
Allele
A particular version of a gene
Gene
(1) In a molecular context, a section of DNA (or RNA, for some viruses) that contains the regulatory sequences and coding information for the transcription of one or more related functional RNA molecules, some of which encode polypeptides. (2) In Mendelian genetics, the hereditary determinant of a trait, such as flower color or seed shape in pea plants.
Autosomal Inheritance
The inheritance patterns that occur when genes are located on autosomes rather than on sex chromosomes
Homozygous
Having two identical alleles of a gene
Heterozygous
Having two different alleles of a gene
Dominant Allele
Referring to a trait or allele whose phenotypic effect is observed when it is present in homozygous or heterozygous form. Dominant typically is used to mean complete dominance.
Recessive Allele
Referring to a trait or allele whose phenotypic effect is observed only in homozygous individuals. Compare with dominant.
Pure line
In genetics, a strain that produces offspring identical to the parents when self-fertilized or mated within the strain. Pure lines are homozygous for the gene under study
Hybrid
The offspring of parents from two different strains, populations, or species
Reciprocal cross
A cross in which the mother’s and father’s phenotypes are the reverse of those examined in a previous cross.
Test Cross
Experiment Mendel used
X Linkage
X chromosome are said to be X-linked. X-linked genes have distinctive inheritance patterns because they are present in different numbers in females (XX) and males (XY).
Y Linkage
Genes located on Y chromosomes
Monohybrid Cross
A mating between two homozygous parents that differ in alleles of one gene. Produces monohybrid offspring. A monohybrid cross is usually continued through the generation
Dihybrid Cross
A mating between two homozygous parents that differ in alleles of two different genes. Produces dihybrid offspring. A dihybrid cross is usually continued through the generation
Principle of Inheritance
mendels principles