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- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/07%3A_Cell_Division/7.07%3A_MeiosisThis page covers meiosis, a crucial process in sexual reproduction that produces four haploid cells from one diploid cell, involving two divisions and featuring genetic recombination and chromosome as...This page covers meiosis, a crucial process in sexual reproduction that produces four haploid cells from one diploid cell, involving two divisions and featuring genetic recombination and chromosome assortment for diversity. It highlights the importance of checkpoints to prevent errors, which, if present, can lead to chromosomal abnormalities such as monosomy, often lethal, and trisomy, which can result in conditions like Down syndrome.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/14%3A_Embryonic_Development_and_its_Regulation/14.04%3A_The_OrganizerThis page explains the embryonic development of a zygote, highlighting the role of mRNA and protein gradients in determining cell fates, alongside intrinsic signals and cell interactions. It details t...This page explains the embryonic development of a zygote, highlighting the role of mRNA and protein gradients in determining cell fates, alongside intrinsic signals and cell interactions. It details the Spemann organizer's role in gastrulation and parallels with Drosophila development, emphasizing the formation of various organs such as wings, legs, and eyes. Overall, the development process encompasses axis establishment, body part formation, and detail refinement.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Principles_of_Biology/03%3A_Chapter_3/21%3A_Introduction_to_Evolution/21.02%3A_Formation_of_New_SpeciesConsider the two owls: in the north, the climate is cooler than in the south; the types of organisms in each ecosystem differ, as do their behaviors and habits; also, the hunting habits and prey choic...Consider the two owls: in the north, the climate is cooler than in the south; the types of organisms in each ecosystem differ, as do their behaviors and habits; also, the hunting habits and prey choices of the southern owls vary from the northern owls.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/14%3A_Embryonic_Development_and_its_Regulation/14.01%3A_Embryonic_DevelopmentThis page outlines embryonic development in animals, which includes four stages: Cleavage (rapid cell division of the zygote), Patterning (cell organization and body axis establishment), Differentiati...This page outlines embryonic development in animals, which includes four stages: Cleavage (rapid cell division of the zygote), Patterning (cell organization and body axis establishment), Differentiation (activation of zygotic genes for specific cell types), and Growth. It emphasizes the transition from maternal mRNA to the embryo's genome. Research on frogs and snails illustrates the significance of mRNA distribution and protein gradients during early development.
- https://bio.libretexts.org/Workbench/General_Biology_I_and_II/04%3A_Unit_IV-_Evolutionary_Processes/4.2%3A_The_Origin_of_Species/4.2.1%3A_Species_DefinedA biological species is defined as a group of individuals that, in nature, are able to mate and produce viable, fertile offspring. There are other definitions of species but, according to the biologic...A biological species is defined as a group of individuals that, in nature, are able to mate and produce viable, fertile offspring. There are other definitions of species but, according to the biological definition, one species is distinguished from another when, in nature, it is not possible for matings between individuals from each species to produce fertile, living offspring.
- https://bio.libretexts.org/Courses/Gettysburg_College/01%3A_Ecology_for_All/12%3A_Sex_Strategies/12.06%3A_Scientist_Spotlight_-_Ernest_Everett_JustPrior to his time in Chicago, Just conducted research at the Woods Hole Biological Marine Laboratory, where his work with marine invertebrates revealed that the ectoplasm (egg surface) significantly i...Prior to his time in Chicago, Just conducted research at the Woods Hole Biological Marine Laboratory, where his work with marine invertebrates revealed that the ectoplasm (egg surface) significantly influences the fertilization and development of eggs (Just 1919, 1922; Wellner 2010). Despite his major contributions to our understanding of fertilization and evolutionary developmental biology, his work was “...largely forgotten and invisible to the world of biology” (Byrnes and Newman 2014).
- https://bio.libretexts.org/Courses/City_College_of_San_Francisco/Introduction_to_Genetics/04%3A_Mendelian_Genetics/4.01%3A_IntroductionThis page examines Mendel's foundational laws of genetics through his pea plant experiments, detailing the Laws of Inheritance such as Segregation and Independent Assortment. It covers inheritance pat...This page examines Mendel's foundational laws of genetics through his pea plant experiments, detailing the Laws of Inheritance such as Segregation and Independent Assortment. It covers inheritance patterns, dominant and recessive alleles, and the application of Punnett squares in monohybrid crosses. The text also discusses pedigree trees in analyzing genetic diseases like cystic fibrosis, emphasizing Mendel's pivotal role in establishing modern genetics.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/06%3A_Gene_Expression/6.01%3A_One_Gene_-_One_Enzyme_TheoryThis page discusses Neurospora crassa, a fungus that reproduces both asexually and sexually, making it ideal for genetic research due to its rapid growth and haploid lifecycle. It highlights the "One ...This page discusses Neurospora crassa, a fungus that reproduces both asexually and sexually, making it ideal for genetic research due to its rapid growth and haploid lifecycle. It highlights the "One Gene - One Enzyme" theory proposed by Beadle and Tatum, established through UV-induced mutations, which posits that each gene corresponds to a specific enzyme. This theory has since evolved to include all proteins produced by genes across organisms.
- https://bio.libretexts.org/Workbench/General_Ecology_Ecology/Chapter_11%3A_Behavioral_Ecology/11.1%3A_Proximate_and_Ultimate_Causes_of_Behavior/11.1.1%3A_Scientist_Spotlight_-_Ernest_Everett_JustPrior to his time in Chicago, Just conducted research at the Woods Hole Biological Marine Laboratory, where his work with marine invertebrates revealed that the ectoplasm (egg surface) significantly i...Prior to his time in Chicago, Just conducted research at the Woods Hole Biological Marine Laboratory, where his work with marine invertebrates revealed that the ectoplasm (egg surface) significantly influences the fertilization and development of eggs (Just 1919, 1922; Wellner 2010). Despite his major contributions to our understanding of fertilization and evolutionary developmental biology, his work was “...largely forgotten and invisible to the world of biology” (Byrnes and Newman 2014).
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/14%3A_Embryonic_Development_and_its_Regulation/14.02%3A_Frog_EmbryologyThis page describes the development of frog eggs into tadpoles. After fertilization, the zygote undergoes cleavage and forms a blastula with smaller cells. Gastrulation creates germ layers for body ti...This page describes the development of frog eggs into tadpoles. After fertilization, the zygote undergoes cleavage and forms a blastula with smaller cells. Gastrulation creates germ layers for body tissues. The Spemann organizer prompts ectoderm development into neural tissue, essential for the brain and spinal cord. The tadpole hatches as a complete structure and continues to grow by feeding, incorporating organic matter.
- https://bio.libretexts.org/Courses/Gettysburg_College/01%3A_Ecology_for_All/12%3A_Sex_Strategies/12.01%3A_The_paradox_of_sex-_sexual_versus_asexual_reproductionThis is in accord with Charles Darwin, [35] who concluded that the adaptive advantage of sex is hybrid vigor; or as he put it, "the offspring of two individuals, especially if their progenitors have b...This is in accord with Charles Darwin, [35] who concluded that the adaptive advantage of sex is hybrid vigor; or as he put it, "the offspring of two individuals, especially if their progenitors have been subjected to very different conditions, have a great advantage in height, weight, constitutional vigor and fertility over the self fertilized offspring from either one of the same parents."
