AP Biology Chapter 25

protocells

droplets with membranes that maintained an internal chemistry different from that of their surroundings, nonliving structures that are believed to have evolved into prokaryotes

Oparin and Haldane

hypothesized early earth atmosphere composed of ammonia, hydrogen, hydrogen sulfide, carbon dioxide, nitrogen, water vapor, and methane; thought at high temperatures organic compounds could form -> when earth cooled compounds could be found in water + lightning/UV radiation -> chemical reaction -> proteins

Miller and Urey

tested earlier scientist hypothesis in experiments that simulated conditions on early Earth in a closed system and produced a variety of amino acids.

self-replicating RNA

A current leading hypothesis about the first system of inheritance in the earliest life forms involves_____.

Ribozymes

catalytic RNA molecules that function as enzymes and can splice RNA

Fossil record

a historical sequence of life indicated by fossils found in layers of the Earth's crust

Paleontologists

scientists who study the fossil record.

Relative Dating

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. Oldest fossils are found in deepest strata.

Radiometric Dating

a method of determining the absolute age of an object by comparing the relative percentages of a radioactive (parent) isotope and a stable (daughter) isotope

Half-life

Length of time required for half of the radioactive atoms in a sample to decay

Prokaryotes

a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Include the bacteria and cyanobacteria. Earliest living organisms

Aerobic

Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen.

Anaerobic

Lacking oxygen; referring to an organism, environment, or cellular process that lacks oxygen and may be poisoned by it

Eukaryotes

Unicellular nonbacterial organisms bounded by a cell membrane and contains cytoplasm. cytoplasm contains organelles.appeared about 2.1 billion years ago.

Endosymbiotic hypothesis

Explains the origin of eukaryotes from prokaryotes. The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.

Multicellular eukaryotes

organisms with many cells and true nucleus and membrane bound organelles. evolved about 1.2 billion years ago.

Colonization of land

Plants, fungi and animals begin to appear. about 500 million years ago

Continental drift

the gradual movement and formation of continents (as described by plate tectonics). Can help explain unique biogeography.

Mass extintions

brief periods of times where a large number of species disappeared. global event from global environmental changes ( dinosaurs)

Adaptive radiation

Divergent evolution in which ancestral species evolve into an array of species to fit a number of diverse habitats. Common after mass extinctions.

Evo-devo

Evolutionary developmental biology; a field of biology that compares developmental processes of different multicellular organisms to understand how these processes have evolved and how changes can modify existing organismal features or lead to new ones.

Exaptations

Structures that evolve in one context but become co-opted for another function. Feathers may originally have been beneficial for thermoregulation.

Heterochrony

is an evolutionary change in the rate or timing of developmental events. For example, an organism's shape depends in part on the relative growth rates of different body parts during development. Changes to these rates can alter the adult form substantially. Ex increase for bat finger bones lead to flight. decrease for whale hind leg bones leads to loss of hind legs.

Homeotic genes

Any of the master regulatory genes that control placement and spatial organization of body parts in organisms

Hox genes

a group of related genes that control the body plan of an embryo along the anterior-posterior (head-tail) axis