2011-2012

Origin of Life – Ch 14

“…sparked by just the right combination of physical events & chemical processes…”

“…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

Bacteria Archae-bacteria

AnimaliaFungiProtista Plantae

4500

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3500

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2500

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0

1000

Formation of earth

Molten-hot surface ofearth becomes cooler

Oldest definite fossilsof prokaryotes

Appearance of oxygenin atmosphere

Oldest definite fossilsof eukaryotes

First multicellularorganisms

Appearance of animalsand land plants

Colonization of landby animalsPaleozoic

Mesozoic

Cenozoic

Mill

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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 17th 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 (H2O), CO2, N2, NOx, H2, NH3, CH4, H2S

lots of available H & its electron no free oxygen

Energy source lightning, UV radiation,

volcanic

low O2 = organic molecules do not breakdown as quickly

low O2 = organic molecules do not breakdown as quickly

What’s missingfrom that

atmosphere?

Lerman Bubble Model

Water vapor

Condensed liquid with complex, organicmolecules

CondenserMixture of gases("primitiveatmosphere")

Heated water("ocean")

Electrodes discharge sparks

(lightning simulation)

Water

Origin of Organic Molecules Abiotic synthesis

1923Oparin & Haldane propose reducing atmosphere hypothesis

1953Miller & Urey test hypothesis formed organic

compounds amino acids adenine

CH4

NH3

H2

http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter26/animation_-_miller-urey_experiment.html

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-celledcyanobacteria

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 theplasma membrane

DNA

cell wall

plasmamembrane

Prokaryoticcell

Prokaryotic ancestor of eukaryotic

cells

Eukaryoticcell

endoplasmicreticulum (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 cellwith mitochondrion

internal membrane system

aerobic bacterium mitochondrion

Endosymbiosis

mitochondrion

chloroplast

Eukaryotic cell withchloroplast & mitochondrion

Endosymbiosis

photosyntheticbacterium

Endosymbiosis Evolution of eukaryotes

origin of chloroplasts engulfed photosynthetic bacteria,

but did not digest them mutually beneficial relationship

Eukaryoticcell 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