topic 6 origins of life ppt
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DAY 1Topic 6 – Origins of Life
1. Grab a Biology EOC Exam Preparation Worksheet
2. Provide a GIST of the Question.
3. Bubble your answer.4. Explain why you believe is
the correct answer.5. BE PREPARED TO
PARTICIPATE IN CLASS DISCUSSION.
6. After correcting, reflect on our answer.
DO NOW
Theory or Law?
ORIGINS OF LIFE
I will recognize the differences between theories and laws.
I will apply knowledge of the development of a scientific theory.
SC.912.N.3.4 Recognize that theories do not become laws, nor do laws become theories; theories are well-supported explanations and laws are well-supported descriptions.
WHAT ARE WE LEARNING TODAY?
Benchmarks Learning Objectives
How does a theory become a law? Explain.
WHAT IS THE ESSENTIAL QUESTION?
Look, Kid, I don't know why. Ask him to explain it!
THINK – WRITE – PAIR – SHAREScientific Theories Explained1. What is the everyday use of
the word theory?2. What is a scientific theory?3. Give an example of a
scientific theory4. Can a scientific theory
change?
Scientific Laws Explained
1. What is the everyday use of the word law?
2. Can a law be broken?3. What is a scientific law? Can
it be broken?4. Give an example of a
scientific law.
How does a law differ from a theory?
How does a scientific theory become a law?
HOW ARE THEORIES AND LAWS RELATED?
Scientific Theory Scientific Law
Description of what happens in nature.
Explains how things behave.
Generally accepted to be true and universal.
Explanation of a set of related observations or events based upon
proven hypotheses and verified multiple times.
Explains why things behave the way they do.
Subject to change as new information is available.
HOW ARE THEORIES AND LAWS RELATED?
In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a
whole, and represent the tools and products of science.
Scientific Laws
Scientific Theories Science
Collaborative Activity
Title: Development of a Scientific Theory
Problem Statement: Why are theories never proven or considered absolute truths?
Look, Kid, I don't know why. Ask him to explain it!
Collaborative ActivityFirst discovery in the 1600’s:1. Remove one piece of the puzzle from the
envelope.2. Write a hypothesis that best describes what
your group thinks the picture on the puzzle will look like.
Second discovery early 1800’s: 3. Remove 10 pieces of the puzzle from the
envelope. 4. After examining the pieces, develop a
second hypothesis about the complete scene or picture shown represented by the puzzle.
5. Identify the key evidence used to support the hypothesis.
Collaborative ActivityThird discovery early 1900’s: 6. Remove another 15 pieces of the puzzle from
the envelope and either retain or revise your 1st and 2nd hypotheses or develop a 3rd hypothesis.
7. Again cite the key evidence should be identified.
Fourth discovery late 1900’s:8. Remove an additional 20 puzzle pieces from
the envelope and proceed as in step 6.9. Collect evidence seen and develop a final
hypothesis.10.State your hypothesis and the evidence you’ve
accumulated to support it. 11.DRAW WHAT YOU THINK THE PICTURE WILL
LOOK LIKE.
DAY 2Topic 6 – Origins of Life
1. Grab a Biology EOC Exam Preparation Worksheet
2. Provide a GIST of the Question.
3. Bubble your answer.4. Explain why you believe is
the correct answer.5. BE PREPARED TO
PARTICIPATE IN CLASS DISCUSSION.
6. After correcting, reflect on our answer.
DO NOW
MACROMOLECULES ARE POLYMERS MADE UP OF MANY MONOMERS
Monomer - small molecular subunit which joins with similar units to form a polymer.
Polymer - consists of up to millions of repeated, covalently linked monomers.
MonomerPolymer
PROTEINS Are macromolecules that contain nitrogen as well as carbon,
hydrogen, and oxygen. Made up of a repeating chain of amino acids.
Are used to build muscle and can be found in beef, chicken, eggs, tofu, beans, and fish. Denature under exposure to heat – that’s what causes the egg to turn white!
PROTEINS
Experiment conducted in 1953 by Staley L. Miller and Harold C. Urey
Their apparatus, illustrated inthe figure included a: Gas chamber containing gases
present in Earth early atmosphere Electrodes supply electricity to
provide energy to drive chemical reactions Water chamber substituted for the oceans and lakes.
The Miller-Urey experiment produced a variety of organic compounds, including amino acids.
HOW DID THE FIRST ORGANIC COMPOUNDS FORM?
WHAT ARE WE LEARNING TODAY?BenchmarksSC.912.L.15.8 – Describe
the scientific explanations of the origin of life on Earth.
Learning Objectives I will describe scientific
explanations of the origin of life on Earth.
I will identify situations or conditions contributing to the origin of life on Earth.
Scientists explain that that life arose from nonlife billions of years ago through the theory of abiogenesis. Could life arise from nonlife today? Explain.
WHAT IS THE ESSENTIAL QUESTION?
WHAT CONDITIONS MAKE EARTH UNIQUE? Only planet known to sustain life. Several conditions make
Earth able to sustain life aswe know it. presence of liquid water moderate temperature
range free oxygen in the
atmosphere adequate sunlight no toxic substances in the atmosphere absence of lethal radiation
WHAT WAS EARTH LIKE? Earth’s early atmosphere probably contained hydrogen cyanide,
carbon dioxide, carbon monoxide, nitrogen,hydrogen sulfide, and water.
Volcanic activity probably formed it. Released great amounts of water vapor
that later condensed to form oceans. Released CO2 that warms the
atmosphere by absorbing outgoing heat. How did that affect the temperature?
This early atmosphere lackedoxygen, so it could not support life as we know it today. WHERE DID LIFE BEGIN? HOW DID LIFE BEGIN? WHAT DID IT LOOK LIKE? SO MANY QUESTIONS!!!
Proposed by Alexander Oparin and John Haldane. Early atmosphere contain
NH3, CO2, H2O, H2, and CH4
At high temperatures, these gases may have formed single organic compounds.
When Earth cooled and water vapor condensed, these simple organic compounds would have collected in lakes and oceans.
Overtime. these compounds could have entered complex chemical reactions, fueled by energy from ultraviolet radiation, volcanic eruptions, and lighting.
Fossil evidence indicates that life on Earth appeared about 3.5 billion years ago in the oceans Provided protection
from UV radiation Allowed
multidirectional movement
Served as a medium for essential chemical reactions.
Anaerobic prokaryotes
WHERE DID LIFE BEGIN?Fossil Evidence Primordial Soup Theory
Abiogenesis or spontaneous generation states that life can arise from nonliving things Oparin reasoned that O2 prevents
the synthesis of certain organic compounds that are necessary building blocks for the evolution of life
Oparin proposed that the "spontaneous generation of life" did in fact occur once, but was now impossible because the conditions found on the early Earth had changed
Oparin argued that a "primeval soup" of organic molecules could be created in an oxygen-less atmosphere.
Biogenesis states that every living thing came from a pre-existing living thing. In 1668 Francesco Redi, proved
that no maggots appeared in meat when flies were prevented from laying eggs.
In 1768, Lazzaro Spallanzani demonstrated that microbes were present in the air, and could be killed by boiling.
In 1861, Louis Pasteur performed a series of experiments which demonstrated that organisms such as bacteria and fungi do not spontaneously appear in sterile, nutrient-rich media.
ABIOGENESIS VS. BIOGENESIS
Can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen
Demonstrated in the famous Miller-Urey experiment reported in 1953
New evidence suggestthat it may haveoccurred in volcanicclouds
These vents release important hydrogen-rich molecules
Mineral catalysts could have made critical reactions occurs faster
HOW DID LIFE BEGIN?Hydrothermal Vents Electric Spark
Clay may have provided the foundation for first organic compounds.
Mineral crystals in clay could have arranged organic compounds into organized patterns.
Life could have come from outer space in a comet or meteorite.
HOW DID LIFE BEGIN?Panspermia Community Clay
3 billion years ago ice might have covered the oceans.
Protected from UV light, organic compounds may have formed and reacted with one another.
Ice Earth
Sidney Fox and other scientists have done extensive research on the physical structures that may have given rise to the first cells.
Cell like structures, including microspheres and coacervates, form spontaneously in certain kinds of solutions. Coacervates and microspheres like cells can take up certain
substances from their surroundings. Coacervates can grow Microspheres can bud to from smaller microspheres. However,
microspheres and coacervates do not have all of the properties of life.
Unlike cells, microspheres and coacervates do not have hereditary material.
HOW DID CELLS FORM?
About 2.7 b.y.a., cyanobacteria or blue-green algae began photosynthetic reactions
About 1.8 b.y.a, the atmosphere contained abundant free oxygen.Allowed for the development of
more complex, oxygen-breathing life forms
Caused the first mass extinction of organism that had evolved in an oxygen-less planet
Ended the process of chemical evolution
WHEN DID ATMOSPHERIC OXYGEN APPEARED?
Spirulina
According to the endosymbiotic theory, eukaryotic cells formed from a symbiosis among several different prokaryotic organisms. Eukaryote provided a beneficial
environment Prokaryote provided a method of
energy synthesis. Did not receive much support until
the 1960s, when it was championed by Lynn Margulis of Boston University.
HOW DID THE FIRST EUKARYOTES FORMS?Aerobic
prokaryote
Anaerobic eukaryote
WHAT EVIDENCE SUPPORTS THE ENDOSYMBIOTIC THEORY? Mitochondria and chloroplasts contain DNA similar to bacterial
DNA. Mitochondria and
chloroplasts have ribosomes whose sizeand structure closelyresemble those of bacteria.
Mitochondria and chloroplasts, like bacteria, reproduce by binary fission.
Mitochondria and chloroplast replicate independently from the replication cycle of the cells that contains them.
Scientists explain that that life arose from nonlife billions of years ago through the theory of abiogenesis.Could life arise from nonlife today? Explain.
WHAT IS THE ESSENTIAL QUESTION?