Living organisms share 5 characteristics
- they are made up of one or more cells
- they store and process information that is heritable
- they replicate
- as populations, they involve
- they use energy
viruses
- have the ability to store and transmit information in DNA or RNA
- because viruses cannot independently replicate or independently harness energy, they are not considered to be living organisms
dogma
a principle or set of principles laid down by an authority as incontrovertibly true
Why do cells exist?
- concentrates reagents for biological reactions
- chemical gradients can be used to store energy
- links a phenotype to the same space as the genotype that encodes it
Cell theory
- a cell is a highly organized compartment bounded by a plasma membrane that contains concentrated chemicals in an aqueous solution
- all organisms are made of cells, all cells come from pre-existing cells
- within a multi-cellular individual, all cells are descended from the zygote
- a zygote is derived from other cells (egg and sperm)
Cell features
- cells contain DNA that encodes physical attributes
- cells have a boundary between them and the environment
- cells have the ability to harness materials and/or energy
Flask experiment
experiment to see if cells come from pre-existing cells
Theory of Evolution by Natural Selection
Darwin and Wallace proposed that all species are related by common ancestry and that the characteristics of species can change from generation to generation
Evolution
postulates that species are related to one another and can change through time
Natural selection
a process that explains how evolution occurs
Fitness
the ability of an individual to produce offspring (more to come)
Adaptation
a characteristic that increases the fitness of an individual in a particular environment, also the process of a species acquring fitness-improving traits over time
Natural selection
in order to occur you need:
1) variation
2) heritable
3) influences offspring
- if certain heritable characteristics lead to increased success in producing offspring, then these traits become more common in the population over time
Natural selection on populations
- natural selection acts on individuals
- evolutionary change affects only populations
Tree of life
diagram that depicts relationships relationships among species
Estimating the tree of life
molecular variation in nucleotides (DNA, RNA) offers info for understanding the evolutionary relationships among all orgnanisms
Changes to the tree of life
- indicates 3 major groups of organisms: eukaryotes (Eukarya) and prokaryotes (Bacteria and Archaea)
- taxonomic level is called the domain
Artificial selection
- a form of natural selection where humans drive the course of evolution
- repeating this process over generations results in changes in the characteristic of a domesticated population over time
Vestigial Traits
- loss of traits we no longer need
- traits that have lost their ancestral function in a species but are still retained by that species
- ex: goosebumps, tailbones, hindlimbs on whales, pelvic spurs on pythons
