Biology I Chapter 14 History of Life

Do Now What are the four major types of organic compounds found in living things? Carbohydrates Lipids Proteins Nucleic acids

Do Now What are the four major elements common to all living things? Carbon Hydrogen Oxygen Nitrogen

Biogenesis Spontaneous Generation-living things arise from nonliving things Biogenesis-all living things come from other living things “bio”=life “genesis”=beginning

Francesco Redi’s Experiment Redi’s experiments showed convincingly that flies come only from eggs laid by other flies by placing meat in 2 containers and covering one of them.

Spallanzani’s Experiment Spallanzani concluded that the boiled broth became contaminated only when microorganisms from the air entered the flask. Vital Force

Pasteur’s Experiment With Pasteur’s experiment, the principle of biogenesis became a cornerstone of biology. Used a curve-necked flask.

Formation of the Earth Factors in the formation of Earth: Earth was formed from debris that circled the sun as it formed. Pieces of debris in space added to the size of Earth. Pieces of debris in space collided with Earth, thereby heating it.

The age of Earth is estimated to be approximately 4 billion years. Earth’s Age The age of Earth is estimated to be approximately 4 billion years.

Radiometric Dating Atomic number=# of protons Mass Number=# of protons + # of neutrons Isotope-same # of protons,different # of neutrons Radioactive Isotope-some isotopes have unstable nuclei that release particles or radiant energy until the nuclei becomes stable.

Radiometric Dating Radiometric Dating-a method of establishing the age of materials by looking at isotopes The age of fossils can sometimes be determined by measuring the amount of a specific radioactive isotope in the fossil bones.

Half-Life Half-life-the amount of time it takes for one-half of any size sample of an isotope to decay to a stable form

Alexander Oparin Oparin believed that macromolecules, such as proteins, first appeared in water. Thought that the early atmosphere contained ammonia, hydrogen gas, water vapor, and compounds made of hydrogen and carbon, such as methane. According to Oparin, at high temperatures, these gases might have formed simple organic compounds, such as amino acids.

Miller & Urey Stanley Miller and Harold Urey set up an experiment using Oparin’s hypothesis as a starting point. Miller and Urey did not use oxygen gas in their apparatus because oxygen was not believed to have been present in Earth’s early atmosphere. The experiment produced a variety of organic compounds, including amino acids.

RNA RNA: Was probably the first genetic molecule. Can undergo natural selection and thus can evolve. Probably evolved before DNA. The first information-sorting molecule to form on Earth.

The First Cells Scientists have inferred that the first cells were prokaryotic, anaerobic, and heterotrophic. Probably similar to archaeabacteria.

Chemosynthesis Chemosynthesis differs from photosynthesis in the source of energy used to produce organic molecules.

Photosynthesis and Aerobic Respiration The surface of Earth is protected from damaging ultraviolet light by ozone (O3).

The First Eukaryotes Many scientists think that early aerobic prokaryotes invaded larger cells and eventually gave rise to mitochondria. (endosymbiosis)