17.3- Molecular Clocks Flashcards

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1
Q

Model that uses mutations rates to measure evolutionary time

A

Molecular clocks

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2
Q

DNA found in mitochondria, often used as a molecular clock

A

Mitochondrial DNA

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3
Q

RNA that is in the ribosomes and also used as a molecular clock and guides the translation of mRNA into a protein.

A

Ribosomal RNA

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4
Q

Who proposed a new way to measure evolutionary time in the 1960s?

A

Linus Pauling and Emilie Zuckerkandl

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5
Q

What did Pauling and Zuckerkandl do (experiment)?

A

They compared amino acid sequences of hemoglobin from a wide range of species.

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6
Q

What did Pauling’s and Zuckerkandl’s findings show?

A

They showed that the more distantly related 2 species are, the more amino acids differences there were in their hemoglobin.

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7
Q

What did Pauling and Zuckerkandl use their data for?

A

To calculate a mutation rate for part of the hemoglobin protein.

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8
Q

What do different molecules have?

A

Different mutation rates

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9
Q

How do scientists choose a molecule to use as a molecular clock?

A

Based on how closely related the 2 species are.

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10
Q

Why do scientists use mitochondrial DNA to trace mutations?

A

They’re passed down unshuffled.

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11
Q

Why is mtDNA good for closely related species?

A

The mutation rate is 10 times faster than nuclear DNA.

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12
Q

When is rRNA best to use as a molecular clock?

A

When you’re dealing with distantly related species.

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13
Q

What kind of mutation rate does rRNA have?

A

A slow rate which is best for longer time scales.

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14
Q

What did Pauling and Zuckerkandl find that mutations do for a group of related species?

A

Add up at a constant rate.m

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15
Q

What can scientists do if they know when species began to diverge?

A

They can find the mutation rate for the molecule they’re studying.

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16
Q

What did Pauling and Zuckerkandl do to prove that the number of amino acid differences increases with evolutionary time?

A

They compared their molecular data with the fist appearance of each type of organism in the fossil record.

17
Q

What must scientists find to estimate mutation rates?

A

Find links between molecular data and real time

18
Q

What happens as time passes since 2 species diverged?

A

More mutations build up in each lineage and there’s more differences between 2 species at molecular level

19
Q

Theoretical clock that uses the rate of mutation to measure evolutionary time

A

Molecular clock