chapter 1: biology and the tree of life Flashcards
organsim
a life-form made up of 1+ cells
cells
membrane-bound units that make up organisms
genes
units of hereditary information
five fundamental characterisitcs of life
- cells
- replication
- evolution
- information
- energy
theory
an explanation for a general class of phenomena or observations that are supported by a wide body of evidence (not a speculation or guess)
Robert Hooke
Englishman who discovered compartments (“cells”) in cork by using a microscrope in 1665
Anton van Leeuwenhoek
Dutch scientist who developed more powerful microscopes and discovered single-celled organisms in pond water (“animalcules”)
Rudolf Virchow
German scientist who proposed that all cells arise from cells already in existence (“all-cells-from-cells hypothesis”)
cell theory
all organisms are made of cells, and all cells come from preexisting cells
hypothesis
a testable statement explaining a phenomenon or a set of observations (hypotheses = tightly focused questions; theories = proposed explanations for broad patterns)
Louis Pasteur
French scientist whose experiment (involving two flasks, a straight-necked flask with broth exposed to cells in the air and a swan-necked flask that prevented the broth from coming in contact with cells) provided conclusive evidence for the all-cells-from-cells hypothesis over the spontaneous generation hypothesis
experiment
a test of the effect of a single, well-defined factor on a particular phenomenon
experimental prediction
a measurable or observable result that must be correct if a hypothesis is valid
chemical evolution
the process through which life arose from non-life early in Earth’s history
species
distinct, identifiable types of organisms
Charles Darwin and Alfred Russel Wallace
English scientists who indepedently developed the theory of evolution and proposed the idea of natural selection
evolution
a change in the characteristics of a population over time; occurs when heritable variation leads to differential success in reproduction
population
a group of individuals of the same species living in the same area at the same time
natural selection
the proccess (acting on individuals) by which evolution occurs; when heritable traits leads to increased reproductive success, those traits become more common in the population over time. this explains why species change over time and why they are so well-adapted to their habitats.
heritable characteristics
traits that can be passed on to offspring
speciation
process by which natural selections causes a population of one species to diverge and form a new species
fitness
an individual’s ability to produce surviving offspring
adaptation
a trait that increases the fitness of an individual in a particular environment
chromosome theory of inheritance
inside cells, hereditary information is encoded in genes (genes = units located on chromosomes; specific segments of DNA)
Walter Sutton and Theodor Boveri
proposed the chromosome theory of inheritence in 1902
chromosome
consists of a molecule of DNA
deoxyribonucleic acid (DNA)
hereditary material
James Watson and Francis Crick
proposed that DNA is a double-stranded helix
Rosalind Franklin
scientist whose research led to the model proposed by James Watson and Francis Crick
double helix
each strand is composed of varying sequences of building blocks, and the two strands are joined by connections between the building blocks (A-T; C-G)
central dogma
the flow of information in cells: DNA –> RNA –> proteins (first articulated by Francis Crick)
ribonucleic acid (RNA)
a copy of a particular gene’s information; read by molecular machine to make proteins
protein
required for the formation of structural components of the cell and for the promotion of life-sustaining chemical reactions
adenosine triphosphate (ATP)
chemical energy; one of the fundamental nutritional needs of organisms
tree of life
a family tree of organisms describing relationships between species, starting with a single acenstral species (according to the theory of evolution by natural selection)
Carl Woese
first to analyze organisms’ molecular components to establish evolutionary relationships
phylogeny
genealogical history (“tribe-source”)
phylogenetic tree
a diagram that depicts evolutionary history by showing relationships between species
LUCA
“last universal common ancestor”; original ancestral population of the tree of life/universal tree
three fundamental groups (domains) of organisms
- the Bacteria
- the Archaea
- the Eukarya
eukaryotes
have a membrane-bound nucleus; many are multicellular
prokaryotes
have no nucleus; vast majority are unicellar
taxonomy
the naming and classification of organisms
taxon (pl. taxa)
in taxonomy, any named group of organisms
domain
a new taxonomic category proposed by Woese consisting of the Bacteria, Archaea, and Eukarya
phylum (pl. phyla)
major lineages within each domain; major branches on the tree of life (somewhat arbitrary)
Carolus Linnaeus
Swedish botanist who in 1735 devised a system for naming species that is still in use today (capitalized genus name + lowercase species name)
genus (pl. genera)
a group of closely related species (e.g., Homo)
species
species name (e.g., “sapiens” in Homo sapiens) always preceded by its genus
scientific (Latin) name
an organism’s genus and species designation (always italicized)
hypothesis testing steps
- state the hypothesis (the proposed explanation) as preciely as possible and list the predictions it makes (the observable outcomes)
- design a study to test the predictions
null hypothesis
specifies what should be observed wehn the hypothesis being tested is incorrect
control
checks for variables (other than the one being tested) that might influence an experiment’s outcome
three of the greatest unifying ideas in biology
- cell theory
- theory of evolution
- chromosome theory of inheritance
A chromosomes consists of (1) _____. Genes, located on (2) _____, consist of (3) _____ that (4) _____.
(1) a molecule of DNA, the hereditary material
(2) chromosomes
(3) speific segments of DNA
(4) code for products in the cell
