Evolution

EVOLUTION

• Theory, which means: based on fact, but not proven

EVOLUTION

• 3.5- 3.9 billion years ago, first organisms appeared

• probably prokaryotes; one celled without a nucleus

• eventually mutations occurred that formed eukaryotes

• one celled organisms with a nucleus.

Fossil evidence

• evidence of plants and animals that used to live

• found in sedimentary rock

• relative dating: the oldest is on the bottom layer, the newest fossil is on the top layer

radiometric dating

• using radioactive isotopes to find age of fossils

mass extinction

• when many organisms stop existing all at the same time

Extinction

• Give a possible reason this species died out

Reasons may include

• Loss of food• Loss of habitat

(change in shelter or protection)

• Increased predation

• Sudden Climate change

Evolutionary relationships• This diagram

illustrates a proposed evolutionary path for certain organisms.

• 2 organisms that will probably have the greatest similarity of DNA base sequences are

• H and J

• shows that change takes time and is not predictable

• the most recent ancestor of organism F is organism C

• if A is a multicellular heterotroph, organism B is probably a multicellular heterotroph

Beaks of Finches

The technique in use today that will speed up the evolution

of a species• is genetic engineering because DNA

is being changed in a lab, not waiting for a change to occur with normal reproduction (ex. firefly gene into mice)

Adult T cell lymphoma leukemia (ATLL cancer)

• took a firefly glow gene inserted it into tumor cells. • That gene produces the enzyme luciferase in the

insects which, when combined with another compound, luciferin, causes the firefly's distinctive glow.

• The mice then received these genetically modified tumor cells and the researchers injected luciferin into the animals. Cancer cells containing the luciferase would combine with the luciferin and glow in the dark, giving the team a clear picture of the extent of disease inside the animal.

• Then did drug studies to see what drugs worked better

Mice in dark chamber, low light detecting camera

NATURAL SELECTION (page 401)

• Darwin, 1831, sailed on ship called the Beagle to the Galapagos Islands

• Darwin knew that most species overproduce, but do not overrun their ecosystem.

• Most species struggle to survive because of

• Food, water• space • competition … predators

Finches

• Found that the birds on the islands were finches, but had different characteristics than the finches back in England.

• If a species can eat, it will reproduce, therefore passing its genetic code or traits to the next generation. This is the basis for Natural Selection

• The finches therefore had different beaks because of different food supplies

CAUSES OF NATURAL SELECTION

• change in food, change in predator, change in climate

• change in reproductive patterns • Amish exhibited higher incidence of rare

alleles, after religion was established• Bacteria that develop penicillin

resistance- rare one survives, and can reproduce. Over time, increases in population

What we are seeing now, with increased drought

• Forest turns to desert, (desertification); insects with tan color used to be 0.5% of population,

• now tan survives, becomes 99%,

• green color is now 0.5%

EVIDENCE FOR EVOLUTION• An adaptation is any variation that allows

survival• Usually occurs over long periods of time• 2 variations that help organisms include• Mimicry : look like dangerous organism • Camouflage: blend in• Evidence for Evolution includes Fossils

Homologous structures

• structures that look similar• 2 examples include: whale and crocodile • Both have a forelimb

Vestigial Structures

• a body part with no apparent function

• For example appendix in humans• eyes on blind mole-rats

Embryology

• Embryos of different organisms develop through similar stages

• For example tail and gill slits in human embryo

Biochemistry

• comparing DNA and RNA and proteins from different species.

• all life has DNA…. That is amazing• And all DNA is made of sugars and

phosphates with • Adenine, thymine, cytosine and

guanine as the nitrogen bases…..wow

OTHER NAMES IN EVOLUTION(Science Dudes)

• Redi: late 1600’s- used a controlled experiment to disprove spontaneous generation, meaning organisms could just (poof!) appear from the air

• formed theory of BIOGENESIS meaning life only comes from living creatures

Linneaus

• late 1700’s (time of our Revolution)• father of modern classification:

based classification system on characteristics of the organism (shape of leaf, number of legs)

LaMarck

• early 1800’s • Scientist who thought that a trait was

created by a force in nature, and could be passed to the next generation.

• for example, • giraffe’s neck is long due to its need to

stretch to reach the leaves. • if you lose an arm, your child will have

a problem with its arm

Pasteur

• mid 1800’s- • proved milk goes sour because of

microorganisms (bacteria), NOT because of bad spirits in the air.

• Disproved spontaneous generation (POOF!)- Developed Pasteurization which heats and cools milk quickly to stop growth of bacteria

Work on the questions

• Alone

• By yourself

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