genbio

• Genetic engineering: Changing the DNA  in  living organisms to create something new.
• Genetically Modified organism are called  transgenic organism; since genes are transferred from one organism to another.
• Artificial selection: breeders choose which organism to mate to produce offspring with desired traits.
• Selective breeding: when animals with desired characteristics are mated to produce offspring with those desired traits.
• Inbreeding breeding of organism that genetically similar to maintain desired traits.
• Hybridizations: two individuals with unlike characteristics are crossed to produce the best in both organisms.
• Variation: difference between individuals of a species.
• Natural Selection - is the process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. This variation means that some individuals have traits better suited to the environment than others.

   
• Stabilizing Selection - This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for.
• Directional Selection - Happens when a change in the environment causes change in the observable spectrum of phenotypes. 
• Diversifying or disruptive selection - This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait.
• Artificial selection is the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations.
• Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to the chance of sampling error.
• Genetic drift occurs in all populations of non-infinite size, but its effects are strongest in small populations.
• Bottle neck effect - when a population is sharply reduced in size by a natural disaster
• Founder effect - when a small group splits off from the main population to found a colony
• Mutation - is a change in a DNA sequence.
• Recombination is a process by which pieces of DNA are broken and recombined to produce new combinations of alleles
• Gene flow or Migration - The introduction of genetic material (by interbreeding) from one population of A species to another, thereby changing the composition of the gene pool of the receiving population.

   
• Taxonomy – science of naming and grouping species to construct an internationally shared classification system
• The taxonomic classification system invented by a Swedish naturalist named Carl Linnaeus uses a hierarchical system
• Aristotle was the earliest to attempt a more scientific basis for the classification of organisms.
• Aristotle classified plants trees, shrubs & herbs, and animals into 2 groups- those with red blood & without red blood.
• Was proposed by Carl Linnaeus (1758) - This system classifies organisms into Two Kingdoms – Plantae and Animalia
• • Prokaryotes (Bacteria, cyanobacteria) and eukaryotes (fungi, mosses, ferns, gymnosperms & angiosperms) were included under ‘Plants’ based on the presence of cell wall. But they are widely differed in other characteristics.
• It is proposed by R.H. Whittaker (1969) - It includes Monera, Protista, Fungi, Plantae & Animalia. (This is based on cell structure, thallus organization, mode of nutrition, reproduction and phylogenetic relationships)
• Nodes:  represent a place in a phylogenetic tree where one species gets separated from another. Here branching occurs.
• Branches: It is a line that represents ancestors and their descendants. It starts from nodes. 
• Monophyletic clades: It represents the relationship of descendants with their most common ancestors. Presented by a single line in the phylogenetic tree.
• Taxa: A specific group of organisms. Tips of phylogenetic trees end in taxa.
• Cladistics classification includes the comparison of traits of one species with another and finding similarities among the ancestors and their descendants to create a relationship among them.
• Cladistics theory creates clades of organisms that are represented with the help of a cladogram.
• Paraphyletic clades: this clade includes an ancestor and multiple descendants, removing some 2-3 groups.
• Polyphyletic clades: in this clade, organisms possess homoplasy traits. It means organisms in a group show similar characteristics, but they don’t.
• Homologous traits – share similar physical features and genetic sequences because they stem from common evolutionary paths (share common ancestor)
• Analogous traits -  separate evolutionary origins but similar traits from similar environmental conditions
• Analogous traits Ex: bird wings and bat wings
• Homologous traits Ex: 4 limbs (tetrapod)
• Cladogram is a diagram that represents the evolutionary relationships among organisms. 
• Phylogeny is a kind of classification in which organisms can be classified with the help of their basic physical traits. In simple words, those organisms who have a similar kind of body structure will be grouped.