Chapter 25

1. Paleozoic 2. Mesozoic 3. Cenozoic

3 eras

1. Hadean 2. Archean 3. Proterozoic 4. Phanerozoic

4 eons

1. inner membrane of mitochondria/chloroplasts have enzymes and transport systems homologous to living bacteria 2. circular DNA 3. similar reproduction to bacteria 4. same ribosomes as bacteria

4 pieces of evidence for endosymbiosis theory

1. reproduction 2. passing traits to offspring 3. metabolism 4. maintain homeostasis 5. ability to grow and develop 6. made of cells 7. responsiveness to environment

7 characteristics of life

serial endosymbiosis

A hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells

Cambrian Explosion

A relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change saw the emergence of the first large, hard-bodied animals.

The first atmosphere had little oxygen and was likely thick with water vapor, along with compounds released by volcanic eruptions, such as nitrogen and its oxides, carbon dioxide, methane, ammonia, and hydrogen. As Earth cooled, the water vapor condensed into oceans, and much of the hydrogen escaped into space.

Describe the conditions of early Earth. What was the atmosphere like? How was it different from today?

macroevolution

Evolutionary change above the species level

by creating laboratory conditions comparable to those that scientists at the time thought existed on early Earth. His apparatus yielded a variety of amino acids found in organisms today, along with other organic compounds.

How did the Miller-Urey experiment test this hypothesis? What were the results of this (and later) experiment(s)?

ribozymes

RNA that functions as awn enzyme-like catalyst

some evidence suggests that the early atmosphere was made up primarily of nitrogen and carbon dioxide and was neither reducing nor oxidizing (electron removing). Recent Miller/Urey-type experiments using such "neutral" atmospheres have also produced organic molecules. In addition, small pockets of the early atmosphere, such as those near the openings of volcanoes, may have been reducing. Perhaps the first organic compounds formed near volcanoes.

What are alternative hypotheses regarding the location of the synthesis of the first biological monomers?

Adaptations that made it possible to reproduce on land and that helped prevent dehydration (plant vascular systems and wax coated leaves) Plants appear to have colonized land in the company of fungi, because they aid in the absorption of water and minerals from the soil. The fungi obtain their organic nutrients from the plants. Arthropods were among the first animals to colonize land

What are some of the adaptations we see in plant and animal groups who colonized terrestrial environments?

In a relatively short period of time, predators over 1 m in length emerged that had claws and other features for capturing prey; simultaneously, new defensive adaptations, such as sharp spines and heavy body armor, appeared in their prey

What contributed to the incredible diversity of animal forms during the Cambrian Explosion?

In the 1960's Fox discovered the spontaneous polymerization of amino acids into microspheres Sidney Fox demonstrated amino acids polymerize abiotically if exposed to dry heat. 2.Amino acids collected in shallow puddles along the rocky shore; heat of the sun caused them to form proteinoids= 3. When proteinoids are returned to water, they form cell-like microspheres composed of protein. 4. This assumes DNA genes came after protein enzymes; DNA replication needs protein enzymes.

What do Fox's microspheres reveal about the possibility of polymerization under early Earth conditions?

Fossils contain isotopes of elements that accumulated in the organisms when they were alive. Living organisms consist of both carbon 12 and carbon 14. When an organism dies, carbon 12 content does not change but carbon 14 decays to nitrogen 14. The less carbon 14 the fossil has the older it is.

What do ratios of radioactive isotopes to their stable isotopes or stable decay products tell us about the age of a fossil?

the order of fossils in rock strata tells us the sequence in which the fossils were laid down—their relative ages; story line of events

What does the fossil record tell us about the relative ages of organismal groups?

1. metabolism 2. reproduction 3. maintain homeostasis (internal environment different that external enviroment) The necessary conditions may have been met in vesicles, fluid-filled compartments enclosed by a membrane-like structure.

What three basic functions must a cell perform? For each of these functions, describe how these functions might have been achieved from polymer subunits or simpler functions.

hypothesized that Earth's early atmosphere was a reducing (electron-adding) environment, in which organic compounds could have formed from simpler molecules. The energy for this synthesis could have come from lightning and UV radiation. Haldane suggested that the early oceans were a solution of organic molecules, a "primitive soup" from which life arose.

What was the Oparin-Haldane hypothesis?

In the 1960s Cairns-Smith discovered that clay surfaces could polymerize into amino acids; proposed the theory for the origin of life starting from clays instead of polymers such as RNA

What was the importance of clay in Cairns-Smith's hypothesis about polymerization?

Proterozoic Eon

When did eukaryotes appear?

Phanerozoic eon Paleozoic period

When did larger organisms first colonize the land?

Archaean eon; The earliest direct evidence of life, dating from 3.5 billion years ago, comes from fossilized stromatolites; Stromatolites and other early prokaryotes were Earth's sole inhabitants for about 1.5 billion years.

When did single-celled organisms first appear? What is the evidence?

During the Archaean era; When oxygenic photosynthesis first evolved, free O2 dissolved in oceans and lakes and precipitated as iron oxide sediments. Once oceans and lakes became saturated with O2, it began to "gas out" and enter the atmosphere. In some forms, oxygen can damage cells. The rise in O2 doomed many prokaryotic groups, forcing them to live in anaerobic habitats or to acquire adaptions such as cellular respiration.

When was the oxygen revolution? Where did higher levels of oxygen in the atmosphere come from? How did this affect the prokaryotes living on Earth at this time?

Mesozoic

Which era did dinosaurs live in?

the known fossil record is biased in favor of species that existed for a long time, were abundant and widespread in certain kinds of environments, and had hard shells, skeletons, or other parts that facilitated their fossilization.

Why do we say that the fossil record is biased? How so?

geological record

a standard time scale that divides earth's history into 4 eons and further subdivisions

exertions

a term used in evolutionary biology to describe a trait that has been co-opted for a use other than the one for which natural selection has built it.

microsphere

collections of droplets that are composed of molecules that are organized as a membrane; made up of proteins and lipids and formed into a double lipid bilayer membrane;

protocells

early cells that were droplets with membranes that maintained an internal chemistry different from that of their surroundings

hydrothermal vents

hypothesis that compounds were first produced in areas on the seafloor where heated water and minerals gush from Earth's interior into the ocean.

alkaline vents

hypothesis that compounds were first produced in areas that release water that has a high pH one iw warm rather than hot, may have been more suitable for the origin of life

stromatolites

layered rock that form when certain prokaryotes bind thin films of sediment together

radiometric dating

technique used to determine the age of a possible based on the decay of radioactive isotopes; In this process, a radioactive "parent" isotope decays to a "daughter" isotope at a characteristic rate.

endosymbiosis theory

when a prokaryotic cell engulfed a small cell that would evolve into a mitochondrion