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- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/15%3A_Genes_and_How_They_Work/15.09%3A_Mutation-_Altered_GenesIn the living cell, DNA undergoes frequent chemical change, especially when it is being replicated (in S phase of the eukaryotic cell cycle). Most of these changes are quickly repaired. Those that are...In the living cell, DNA undergoes frequent chemical change, especially when it is being replicated (in S phase of the eukaryotic cell cycle). Most of these changes are quickly repaired. Those that are not result in a mutation. Thus, mutation is a failure of DNA repair.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/17%3A_Biotechnology/17.04%3A_Constructing_and_Using_Transgenic_Organisms/17.4.02%3A_Transgenic_PlantsProgress is being made on several fronts to introduce new traits into plants using recombinant DNA technology. The genetic manipulation of plants has been going on since the dawn of agriculture, but u...Progress is being made on several fronts to introduce new traits into plants using recombinant DNA technology. The genetic manipulation of plants has been going on since the dawn of agriculture, but until recently this has required the slow and tedious process of cross-breeding varieties. Genetic engineering promises to speed the process and broaden the scope of what can be done.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/19%3A_Cellular_Mechanisms_of_Development/19.03%3A_Cell_Differentiation/19.3.02%3A_Embryonic_Stem_Cellsa research team led by James Thomson of the University of Wisconsin reported (in the 6 November 1998 issue of Science) that they were able to grow human embryonic stem (ES) cells in culture. At the t...a research team led by James Thomson of the University of Wisconsin reported (in the 6 November 1998 issue of Science) that they were able to grow human embryonic stem (ES) cells in culture. At the time of implantation, the mammalian embryo is a blastocyst. It consists of the trophoblast — a hollow sphere of cells that will go on to implant in the uterus and develop into the placenta and umbilical cord. inner cell mass (ICM) that will develop into the baby as well as the extraembryonic amnion
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/30%3A_Seed_Plants/30.04%3A_SeedsAngiosperms are the flowering plants; most are terrestrial and all lack locomotion. This poses several problems. Gametes are delicate single cells. For two plants to cross fertilize, there must be a ...Angiosperms are the flowering plants; most are terrestrial and all lack locomotion. This poses several problems. Gametes are delicate single cells. For two plants to cross fertilize, there must be a mechanism for the two gametes to reach each other safely. There must also be a mechanism to disperse their offspring far enough away from the parent so that they do not have to compete with the parent for light, water, and soil minerals. The functions of the flower solve both of these problems.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/25%3A_The_Origin_and_Diversity_of_Life/25.01%3A_Deep_TimeEvolutionary changes coincide with geologic changes on the earth. But consider that changes in geology (e.g., mountain formation or lowering of the sea level) cause changes in climate, and together th...Evolutionary changes coincide with geologic changes on the earth. But consider that changes in geology (e.g., mountain formation or lowering of the sea level) cause changes in climate, and together these alter the habitats available for life. Two types of geologic change seem to have had especially dramatic effects on life: continental drift and the impact of asteroids
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/19%3A_Cellular_Mechanisms_of_Development/19.03%3A_Cell_Differentiation/19.3.01%3A_Stem_CellsStem cells are cells that divide by mitosis to form either two stem cells, thus increasing the size of the stem cell "pool", or one daughter that goes on to differentiate, and one daughter that retain...Stem cells are cells that divide by mitosis to form either two stem cells, thus increasing the size of the stem cell "pool", or one daughter that goes on to differentiate, and one daughter that retains its stem-cell properties. How the choice is made is still unknown. However, several genes have been found whose activity prevents a daughter cell from differentiating.
- https://bio.libretexts.org/Courses/Saint_Mary's_College_Notre_Dame_IN/Foundations_of_Form_and_Function/03%3A_Intro_to_Plants/3.02%3A_Seed_Plants/3.2.05%3A_FruitAngiosperms are the flowering plants; most are terrestrial and all lack locomotion. This poses several problems. Gametes are delicate single cells. For two plants to cross fertilize, there must be a ...Angiosperms are the flowering plants; most are terrestrial and all lack locomotion. This poses several problems. Gametes are delicate single cells. For two plants to cross fertilize, there must be a mechanism for the two gametes to reach each other safely. There must also be a mechanism to disperse their offspring far enough away from the parent so that they do not have to compete with the parent for light, water, and soil minerals. The functions of the flower solve both of these problems.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/25%3A_The_Origin_and_Diversity_of_Life/25.02%3A_Origins_of_LifeTo account for the origin of life on our earth requires solving several problems: How the organic molecules that define life, e.g. amino acids, nucleotides, were created. How these were assembled int...To account for the origin of life on our earth requires solving several problems: How the organic molecules that define life, e.g. amino acids, nucleotides, were created. How these were assembled into macromolecules, e.g. proteins and nucleic acids, - a process requiring catalysts. How these were able to reproduce themselves. How these were assembled into a system delimited from its surroundings (i.e., a cell). A number of theories address each of these problems.
- https://bio.libretexts.org/Workbench/Bio_1130%3A_Remixed/08%3A_Intro_to_Ecology/8.03%3A_Energy_Flow_through_the_Biosphere
- https://bio.libretexts.org/Workbench/General_Biology_I_and_II/04%3A_Unit_IV-_Evolutionary_Processes/4.3%3A_Genes_Within_Populations/4.3.2%3A_Evolution_in_PopulationsThe Hardy-Weinberg law argues that the gene frequencies and genotype ratios in a randomly-breeding population remain constant from generation to generation. Evolution involves changes in the gene poo...The Hardy-Weinberg law argues that the gene frequencies and genotype ratios in a randomly-breeding population remain constant from generation to generation. Evolution involves changes in the gene pool, while a population in Hardy-Weinberg equilibrium shows no change. Hence, populations are able to maintain a reservoir of variability so that if future conditions require it, the gene pool can change.
- https://bio.libretexts.org/Courses/Gettysburg_College/01%3A_Ecology_for_All/06%3A_The_Evolution_of_Populations_and_Species/6.03%3A_The_Hardy-Weinberg_EquilibriumThe Hardy-Weinberg law argues that the gene frequencies and genotype ratios in a randomly-breeding population remain constant from generation to generation. Evolution involves changes in the gene poo...The Hardy-Weinberg law argues that the gene frequencies and genotype ratios in a randomly-breeding population remain constant from generation to generation. Evolution involves changes in the gene pool, while a population in Hardy-Weinberg equilibrium shows no change. Hence, populations are able to maintain a reservoir of variability so that if future conditions require it, the gene pool can change.
