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Bio 94 Ch. 1


Organism a life form-- a living entity made up of one or more cells.
What does it mean to say that something is alive? Although there is no definition of life that is endorsed by all biologists, most agree that organisms share a suite of five fundamental characteristics.
Energy To stay alive and reproduce, organisms have to acquire and use energy. To give just two examples: plants absorb sunlight; animals ingest food.
Cells Organisms are made up of membrane-bound units called cells. A cell's membrane regulates the passage of materials between exterior and interior spaces.
Information Organisms process hereditary, or genetic, information encoded in units called genes. Organisms also respond to information from the environment and adjust to maintain stable internal conditions.
Replication One of the great biologists of the twentieth century, Francois Jacob, said that the dream of a bacterium is to become two bacteria." Almost everything an organism does contributes to one goal: replicating itself.
Evolution Organisms are the product of evolution, and their populations continue to evolve.
Organisms are life forms because they acquire and use energy, are made up of one or more cells, process information, are capable of replication, are a product of evolution.
Theory is an explanation for a very general class of phenomena or observations that are supported by a wide body of evidence.
Cell theory this is expressed by fundamental questions: What are organisms made of? Where do they come from.
The basic conclusion made in the 1800s? All organisms are made of cells
Smallest organisms known today? Bacteria, that are barely 200 nanometers wide, or 200 billionths of a meter.
Cell a highly organized compartment that is bounded by a thin, flexible structure called a plasma membrane and that contains concentrated chemicals in an aqueous (watery) solution
Most scientific theories have two components: The first describes a pattern in the natural world; the second identifies a mechanism or process that is responsible for creating that pattern.
Hooke and his fellow scientists did what? articulated the pattern component of the cell theory.
Complete Cell Theory All organisms are made of cells, and all cells come from preexisting cells.
What does the cell theory maintain? that cells do not spring to life spontaneously but are produced only when preexisting cells grow and divide.
Hypothesis a testable statement to explain a phenomenon or a set of observations
Prediction describes a mesurable or observable result that must be correct if a hypothesis is valid.
Darwin and Wallace important claim concerning patterns that exists in the natural world: 1. Species are related by common ancestry. 2. Darwin and Wallace proposed that the characteristics of species can be modified from generation to generation. Darwin called this process descent with modification.
Evolution A change in the characteristics of a population over time. It means that species are not independent and unchanging entities, but are related to one another and can change through time.
Natural Selection Natural selections occurs when two confirmations are met: 1.Individuals within a population vary in characteristics that are heritable- meaning traits can be passed on to offspring. 2. A population is defined as a group of individuals of the same group
Natural selection vs evolutionary change: Natural selection acts on individuals while, evolutionary change occurs in populations.
Artificial selection changes in populations that occur when humans select certain individuals to produce the most offspring. Beginning in 1896, researchers began long-term selection on maize.
Fitness the ability of an individual to produce viable offspring. Individuals with high fitness produce many surviving offspring.
Adaptation a trait that increases the fitness of an individual in a particular environment.
Tree of life a family tree of organisms.
Phylogeny tribe source- their actual genealogical relationships.
Why might rRNA be useful for understanding the relationships between organisms? The ribonucleotide sequence in rRNA is a trait that can change during evolution.
Theory of evolution in organisms If the theory of evolution is correct, then rRNA sequences should be very similar in closely related organisms but less similar in organisms that are less closely related. ex// plants should share certain changes in rRNA that no other species have.
The tree of life implied by rRNA that there are three fundamental groups or linkages of organisms: the bacteria the archaea the eukarya
Eukaryotic cells have a membrane bound nucleus.
Prokaryotic cells do not have a membrane bound nucleus.
Taxonomy the effort to name and classify organisms.
Created by: destgarcia