Bio T1 Notes PDF

Evolution: The theory of evolution is that all living species are the modified descendants of earlier species, and that we all share a common ancestor in the distant past. Evidence of evolution: -Anatomy: looking at comparisons of today’s very different organisms can show us that they may have been...

Evolution: The theory of evolution is that all living species are the modified descendants of earlier species, and that we all share a common ancestor in the distant past. Evidence of evolution: -Anatomy: looking at comparisons of today’s very different organisms can show us that they may have been related a long time ago. Example, the bones in our arms: -Biochemical: The chemicals that are used in Metabolism and to make up cells have not changed. Example: ATP, the molecule used to generate energy in cells has not needed to change throughout time. Common ancestors evolved ATP and never changed it, because if the change were to not work, the species would die. Evolution is conservative, meaning that if something is working fine, there is no need for innovation. -Development: Comparisons of the early stages of embryonic development can reveal similarities among species that are not obvious from comparisons of adult organisms. -DNA and Genes: The gene Sonic hedgehog in patterning limbs during embryo development is the same in fish, birds and mammals. Homologous vs analogous: Homologous traits are traits that share a similar embryonic origin. Ex: the limbs of tetrapods. Analogous traits are traits that share the same function but NOT the same origin. Ex: wings of birds and bats. Some features of animals can be both a homologous and an analogous trait. For example the wings of birds and bats, which share a similar embryonic origin and have the same purpose (flight). However, birds and bats do not share an ancestor that flew, as they evolved independently. The bone pattern of 1 - 2 - little bones - digits, is found in both birds and bats. Evolutionary Change: Evolution may be defined as changes in the genetic material of a population over time. These changes could be: Adaptive: Increase in frequency of traits that improve chance to survive and reproduce. Random: Frequency of traits in a population changes due to random events. Mechanisms of Evolution: 1. Natural Selection (VIDA): V - Variation: The genetic variation within a population (eye color, tooth length…) I - Inheritance: Traits are passed down from parents to offspring D - Differential survival/Reproduction: Individuals with certain traits are more likely to survive and therefore reproduce A - Adaptation: Over time, the population becomes better adapted to its environment due to the accumulation of beneficial traits. Natural selection is the most important mechanism of evolution because it is the primary driver of adaptation. It allows populations to become better suited to their environments over time. 2. Gene Flow: The migration of organisms into or out of a population which changes the gene pool of each population. (Ex. A red bird flew into a blue bird only zone and started creating more red birds, changing the gene pool of the blue bird population) 3. Genetic Drift: A drastic decrease in the population size, leaving only those genes present in the remaining individuals in the gene pool. (Ex. A volcano exploded killing 90% of the elk population, the genes of the 10% that survived would be more prominent) 4. Mutation: Random changes to a gene that may result in a new trait. (Ex. A gene code for fur color having a mutation might result in a new fur color). Different versions of genes are called alleles. 5. Non-Random Mating: The likelihood that organisms will select their mate based on certain criteria such as color, size, or other mating behaviors. (Ex. In a species of birds, a female bird selects a mate based on his song) Speciation: -A species is often defined as a group of individuals that actually or potentially interbreed in nature. -Speciation is a process that can result from natural selection acting on multiple heritable traits over time. Two species may be considered the same and not the same if they can: -Reproduce a hybrid in nature (same) -Look different (different) -Eat different things (different) -Behave different (different) Reproductive Isolation: Factor that prevents 2 populations from interbreeding when they live in the same region. When populations become isolated they can evolve into two different species Reproductive isolation could develop in a variety of ways including: Behavioral isolation: the presence or absence of a specific behavior that prevents reproduction between two species from taking place. (Ex: singing birds) Geographic isolation: This happens when populations are separated by geographic barriers. Temporal isolation: Two populations reproduce at different times. (Ex. 2 similar orchids that live in the same forest but pollinate on different days, meaning they can’t pollinate each other.) Types of Cells: Prokaryote: -Organisms contain no nucleus or other membrane bound organelles -DNA is found in circular chromosomes and in a loop called a plasmid Eukaryotic: -Cell contains membrane bound organelles (Ex. Nucleus, chloroplast, mitochondria) -DNA is found in linear chromosomes Both Cell types have: -Cytoplasm -Cell membrane -Ribosomes Classification: Taxonomy: Science of identifying and classifying all organisms. Phylogeny: The study of the evolutionary relationships among species. Limiting Factors: Factors in an environment capable of limiting the growth of a population (Ex: lack of food) Selective Pressure: Causes that reduces or increases reproductive success in a portion of a population. (Ex: Predators) The Linnaean System: -Named after Swedish botanist, Carl Linnaeus -Consists of hierarchy of taxa(groups) -Based on similarity of traits Phylogenetic Trees (Cladogram): -Represent evolutionary relationships among a group of organisms -Tips of tree are descendant taxa -Nodes of the tree represent the common ancestor of the descendants -A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor. 6 Kingdoms of Life: Bacteria: -Domain: Bacteria -Unicellular -Reproduce: Asexual -Gain energy: Photosynthesis, Inorganic/Organic compounds -Present in every habitat on Earth (including humans) -Vital in cycling nutrients Archaea: -Domain: Archaea -Unicellular -Reproduce: Asexual, Binary fission -Gain energy: Inorganic/Organic molecules -Extreme environments -Broad range of habitats Protists: -Domain: Eukarya -Mostly unicellular -Reproduce: Asexual/Sexual -Gain energy: Sunlight, Organic compounds -Loose grouping of 30-40 phyla (Ex. Algae, diatoms) Fungi: -Domain: Eukarya -Most are multicellular -Reproduce: Asexual/Sexual -Gain energy: Decomposition of organic compounds -Cell wall made of chitin -Form symbiotic relationships with other organisms -Important in brewing, wine making, antibiotics (Ex. Mushroom, mold, yeast) Plants: -Domain: Eukarya -Multicellular -Reproduce: Asexual/Sexual -Gain energy: Photosynthesis -Cell walls made of cellulose (Ex. Ferns, mosses, plants) Animals: -Domain: Eukarya -Multicellular -Reproduce: Asexual/Sexual -Gain energy: Digest organic materials -Contain protein collagen -Are motile during at least one stage of life -Mostly Invertebrates (97%) (Ex. Worms, jellyfish, insects)