Unit 8—Evolution AP Biology - PowerPoint Presentation

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Unit 8—Evolution

AP Biology

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I. Evolution and Evolutionary

Evolution—change in gene frequency in a population over time

Change must be genetic

Occurs in a population—not individuals

Time depends on how fast environment changes and how fast organisms reproduce

Evolutionary Theory—diversity of organisms on earth is due to evolution from simple to complex

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II. Hypotheses about Origins of Life

Resources for these notes

Bozeman Video—

Abiogenesis

http://www.bozemanscience.com/010-abiogenesis

Campbell Textbook—

Ch. 25.1

Ch. 25.3

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II. Hypotheses about Origins of Life

Spontaneous Generation—thought that life could form from non-living things

1862—Pasteur disproved this idea through is experiments

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II. Hypotheses about Origins of Life

Organic Molecules—Building Blocks of Life

1

st

Organic Molecules made in lab—Miller-Urey 1953

Early earth—reducing environment

Energy—from lightning, UV,…(no ozone yet)

Experiments with these conditions created amino acids (abundantly)…also sugars, lipids, & nitrogenous bases

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II. Hypotheses about Origins of Life

Polymerization—putting pieces together to make macromolecules!

Researchers have made polypeptides without enzymes.

Dehydration by vaporization—drip amino acids on hot sand, clay or rock

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II. Hypotheses about Origins of Life

Membranes—lipids spontaneously form spheres—enclose liquids and form a membrane (

Protobionts

/

Protocells

)

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II. Hypotheses about Origins of Life

1

st

Genetic Material

Life needs replication and replicating molecules

1

st

genes were RNA—which can replicate (“RNA World”)Ribozymes—RNA catalysts—assembled amino acids and replicated RNA (no enzymes or ribosomes yet)

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II. Origins of Life

Prokaryotic

Cells

—First Fossils are

apprx

. 3.5

billion

years old2 Domains—Archaea and Bacteria

2 Hypothesis about how they got their energy

Took ATP from environment

Made ATP from sulfur and iron

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II. Origins of Life

First fossils are

apprx

. 2.1 billion years old

Membrane enfolding

and

Endosymbiosis

(Review!)

D.

Eukaryotic Cells

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III. Developing Ideas about Evolution

Resources

Campbell Textbook

Ch. 22

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III. Developing Ideas about Evolution

Ancient Ideas

Anaximander

– Greek; 500BC; thought perhaps simple things developed into more complex forms

Aristotle

—Greek; 384-322BC; believed that species are “fixed”; created separately and could not be changed

Other cultures

—

e

ach culture had an explanation (varied)

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III. Developing Ideas about Evolution

B. Mid-1700’s– Geology presented several big ideas…

Earth is older than 6000 years

old

Early 1800—

Lyell

—Principals of Geology—gradual forces shape the earth rather than

catastrophesCollections of fossils—found ocean fossils on mountain tops—perplexed scientists

…

Sir Charles Lyell

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III. Developing Ideas about Evolution

Lamarck/Wallace

Lamarck

-Published essay in 1809

“Inheritance of Acquired Characteristics”-changed due to use/disuse and developed traits could be passed on…

Wallace

-Published essay in 1858

Natural selection-slow modification-

didn’t apply to humans

Alfred Wallace

Jean

Baptiste

-Lamarck

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III. Developing Ideas about Evolution

D.

Darwin

—Wrote essay in 1844 but published it in 1858

Darwin’s Voyage—HMS

Beagle

1831-1836—Some observations made on the voyage

Similar adaptations occurred in similar environments

Great diversity within the same environment (ex. Galapagos finches)

Fossils—Darwin developed a large collection

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III. Developing Ideas about Evolution

Charles Darwin and HMS Beagle Voyage

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III. Developing Ideas about Evolution

Darwin’s Explanation—Decent

with Modification

Did not use the term evolution

No supernatural—all based upon what was seen in the natural world

Developed ideas while on HMS Beagle—highly influenced by Malthus, Lyell, and other scientists

Basic idea was that organisms change over time…main mechanism is natural selection…particularly for adaptive change

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III. Developing Ideas about Evolution

Timeline of Scientific Ideas about Geology, Inheritance, Evolution, and Population Limits

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IV. Natural Selection and Artificial Selection

Resources

Bozeman—Natural Selection

http://www.bozemanscience.com/001-natural-selection

Campbell Textbook

Ch. 23

Learn Genetics

http://learn.genetics.utah.edu/content/selection/artificial/

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IV. Natural Selection and Artificial Selection

Natural Selection

–organisms with certain inherited traits tend to survive and

reproduce

at higher rates in their

environment

than other individuals because of those traits.

Differential Reproduction

—organisms overproduce -> not all survive -> those better suited for environment survive -> Reproduce more

Reproduction is what matters—ensures passing on of genes

“Better suited” to survive, not “best”… really survival of the good enough… 

Conditions of environment determine if fit enough

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IV. Natural Selection and Artificial Selection

Adaptation

—genetic trait that helps an organism reproduce

(variations sometimes turn into adaptations, but not always)

Relative Fitness

—the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

**Likelihood of reproducing and passing on genes

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IV. Natural Selection and Artificial Selection

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IV. Natural Selection and Artificial Selection

Artificial Selection– humans determine who reproduces

Can create more change in short period of time

May create artificial environment for artificially selected organisms to survive