Presentation on theme: "2011-2012 Origin of Life – Ch 14 “…sparked by just the right combination of physical events & chemical processes…”"— Presentation transcript:
Origin of Life – Ch 14 “…sparked by just the right combination of physical events & chemical processes…”
Focus of Chapter 14 Matter, Energy, and Organization Life on Earth arose from nonliving matter in a process that required the input of energy. New life-forms evolved from the earliest life-forms, requiring energy input and resulting in highly complex organisms.
Assessing Prior Knowledge 1. Name the elements common to all organic compounds. Carbon Hydrogen Oxygen
2. Name the four types of organic compounds found in living thing and state a major role in each. Carbohydrates - Proteins Lipids Nucleic acids
BacteriaArchae- bacteria AnimaliaFungiProtistaPlantae Formation of earth Molten-hot surface of earth becomes cooler Oldest definite fossils of prokaryotes Appearance of oxygen in atmosphere Oldest definite fossils of eukaryotes First multicellular organisms Appearance of animals and land plants Colonization of land by animals Paleozoic Mesozoic Cenozoic Millions of years ago ARCHEAN PRECAMBRIAN PROTEROZOIC The evolutionary tree of life can be documented with evidence. The Origin of Life on Earth is another story… The evolutionary tree of life can be documented with evidence. The Origin of Life on Earth is another story…
Ch 14-1 Biogenesis Objectives Define spontaneous generation; list observations that led people to think that life could arise from nonliving things. Summarize Redi’s and Spallanzani’s experiments testing spontaneous generation. Describe Pasteur’s experiment and how it disproved the hypothesis of spontaneous generation.
Terms to know Biogenesis - all living things come from other living things. Spontaneous generation – an early and now disproved hypothesis that stated that living organisms develop from nonliving material.
What is Life? First we have to define LIFE… organized as cells respond to stimuli regulate internal processes homeostasis use energy metabolism Develop and Grow change & mature within lifetime reproduce heredity DNA / RNA adaptation & evolution
The Origin of Life is a Hypothesis Extraterrestrial Origin Was the original source of organic (carbon) materials comets & meteorites striking early Earth? Testable Spontaneous Abiotic Origin Did life evolve spontaneously from inorganic molecules? testable
In the 17 th century it was widely believed that living things could arise from nonliving things in a process called spontaneous generation. Explained why: Maggots appeared on rotting meat. Fish appeared in ponds that had been dry the previous season. Today we believe in biogenesis, where all living things come from other living things.
Redi’s Experiment 1668 Showed that rotting meat kept away from flies would not produce new flies. Maggots appeared only on meat that had been exposed to flies.
Spallanzani’s Experiment 1700’s Showed that microorganisms would not grow in broth when its containers was heated and then sealed. Seems to indicate that microorganisms that cause food spoilage do not arise from spontaneous generation but, rather are carried in air.
Pasteur’s Experiment Used a variation of Spallanzani’s design to prove that mo’s are carried in the air and do not arise by spontaneous generation.
14-2 Earth’s History Objectives Describe the conditions of early Earth. Describe the production of organic compounds in the Miller-Urey apparatus. Summarize the possible importance of cell-like structures produced in the laboratory.
Conditions on early Earth Reducing atmosphere water vapor (H 2 O), CO 2, N 2, NO x, H 2, NH 3, CH 4, H 2 S lots of available H & its electron no free oxygen Energy source lightning, UV radiation, volcanic low O 2 = organic molecules do not breakdown as quickly What’s missing from that atmosphere?
Lerman Bubble Model
Water vapor Condensed liquid with complex, organic molecules Condenser Mixture of gases ("primitive atmosphere") Heated water ("ocean") Electrodes discharge sparks (lightning simulation) Water Origin of Organic Molecules Abiotic synthesis 1923 Oparin & Haldane propose reducing atmosphere hypothesis 1953 Miller & Urey test hypothesis formed organic compounds amino acids adenine CH 4 NH 3 H2H2
Stanley Miller University of Chicago produced -amino acids -hydrocarbons -nitrogen bases -other organics It ’ s ALIVE!
Bubbles … Tiny bubbles … Origin of Cells (Protobionts) Bubbles separate inside from outside metabolism & reproduction Microspheres – Primitive cell membranes made of proteins Coacervates – droplets of linked sugars and amino acids
Key Events in Origin of Life Key events in evolutionary history of life on Earth Sun Formation 5 bya Earth Formation 4.5 bya Life originated 3.5–4.0 bya
Radioactive Carbon Dating The process that allows scientists to age objects based on the amount of radioactive material in the object. Radioactive Isotopes are unstable elements that breakdown over time. Radioactive decay is the converting of radioactive material into a stable format through the loss of energy. Half-Life is the amount of time it takes for one half of a given amount of isotope to become stable.
Prokaryotes Prokaryotes dominated life on Earth from 3.5–2.0 bya 3.5 billion year old fossil of bacteria modern bacteria chains of one-celled cyanobacteria
Oxygen atmosphere Oxygen begins to accumulate 2.7 bya reducing oxidizing atmosphere evidence in banded iron in rocks = rusting makes aerobic respiration possible Cyanobacteria - photosynthetic algae
First Eukaryotes Development of internal membranes create internal micro-environments advantage: specialization = increase efficiency infolding of the plasma membrane DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell endoplasmic reticulum (ER) nuclear envelope nucleus plasma membrane ~2 bya
Endosymbiosis Evolution of eukaryotes origin of mitochondria engulfed aerobic bacteria, but did not digest them mutually beneficial relationship Ancestral eukaryotic cell Eukaryotic cell with mitochondrion internal membrane system aerobic bacterium mitochondrion Endosymbiosis
mitochondrion chloroplast Eukaryotic cell with chloroplast & mitochondrion Endosymbiosis photosynthetic bacterium Endosymbiosis Evolution of eukaryotes origin of chloroplasts engulfed photosynthetic bacteria, but did not digest them mutually beneficial relationship Eukaryotic cell with mitochondrion
Evidence structural mitochondria & chloroplasts resemble bacterial structure genetic mitochondria & chloroplasts have their own circular DNA, like bacteria functional mitochondria & chloroplasts move freely within the cell mitochondria & chloroplasts reproduce independently from the cell Theory of Endosymbiosis Lynn Margulis