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Flashcards in chapter 1: biology and the tree of life Deck (55):
1

organsim

a life-form made up of 1+ cells

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cells

membrane-bound units that make up organisms

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genes

units of hereditary information

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five fundamental characterisitcs of life

1. cells
2. replication
3. evolution
4. information
5. energy

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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)

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Robert Hooke

Englishman who discovered compartments ("cells") in cork by using a microscrope in 1665

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Anton van Leeuwenhoek

Dutch scientist who developed more powerful microscopes and discovered single-celled organisms in pond water ("animalcules")

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Rudolf Virchow

German scientist who proposed that all cells arise from cells already in existence ("all-cells-from-cells hypothesis")

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cell theory

all organisms are made of cells, and all cells come from preexisting cells

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hypothesis

a testable statement explaining a phenomenon or a set of observations (hypotheses = tightly focused questions; theories = proposed explanations for broad patterns)

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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

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experiment

a test of the effect of a single, well-defined factor on a particular phenomenon

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experimental prediction

a measurable or observable result that must be correct if a hypothesis is valid

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chemical evolution

the process through which life arose from non-life early in Earth's history

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species

distinct, identifiable types of organisms

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Charles Darwin and Alfred Russel Wallace

English scientists who indepedently developed the theory of evolution and proposed the idea of natural selection

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evolution

a change in the characteristics of a population over time; occurs when heritable variation leads to differential success in reproduction

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population

a group of individuals of the same species living in the same area at the same time

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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.

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heritable characteristics

traits that can be passed on to offspring

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speciation

process by which natural selections causes a population of one species to diverge and form a new species

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fitness

an individual's ability to produce surviving offspring

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adaptation

a trait that increases the fitness of an individual in a particular environment

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chromosome theory of inheritance

inside cells, hereditary information is encoded in genes (genes = units located on chromosomes; specific segments of DNA)

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Walter Sutton and Theodor Boveri

proposed the chromosome theory of inheritence in 1902

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chromosome

consists of a molecule of DNA

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deoxyribonucleic acid (DNA)

hereditary material

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James Watson and Francis Crick

proposed that DNA is a double-stranded helix

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Rosalind Franklin

scientist whose research led to the model proposed by James Watson and Francis Crick

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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)

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central dogma

the flow of information in cells: DNA --> RNA --> proteins (first articulated by Francis Crick)

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ribonucleic acid (RNA)

a copy of a particular gene's information; read by molecular machine to make proteins

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protein

required for the formation of structural components of the cell and for the promotion of life-sustaining chemical reactions

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adenosine triphosphate (ATP)

chemical energy; one of the fundamental nutritional needs of organisms

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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)

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Carl Woese

first to analyze organisms' molecular components to establish evolutionary relationships

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phylogeny

genealogical history ("tribe-source")

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phylogenetic tree

a diagram that depicts evolutionary history by showing relationships between species

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LUCA

"last universal common ancestor"; original ancestral population of the tree of life/universal tree

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three fundamental groups (domains) of organisms

1. the Bacteria
2. the Archaea
3. the Eukarya

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eukaryotes

have a membrane-bound nucleus; many are multicellular

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prokaryotes

have no nucleus; vast majority are unicellar

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taxonomy

the naming and classification of organisms

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taxon (pl. taxa)

in taxonomy, any named group of organisms

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domain

a new taxonomic category proposed by Woese consisting of the Bacteria, Archaea, and Eukarya

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phylum (pl. phyla)

major lineages within each domain; major branches on the tree of life (somewhat arbitrary)

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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)

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genus (pl. genera)

a group of closely related species (e.g., Homo)

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species

species name (e.g., "sapiens" in Homo sapiens) always preceded by its genus

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scientific (Latin) name

an organism's genus and species designation (always italicized)

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hypothesis testing steps

1. state the hypothesis (the proposed explanation) as preciely as possible and list the predictions it makes (the observable outcomes)
2. design a study to test the predictions

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null hypothesis

specifies what should be observed wehn the hypothesis being tested is incorrect

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control

checks for variables (other than the one being tested) that might influence an experiment's outcome

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three of the greatest unifying ideas in biology

1. cell theory
2. theory of evolution
3. chromosome theory of inheritance

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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