Astrobiology Chapter 7: Tree of Life

Question 1

What are the two hypotheses for alien life?

Answer 1

A: Alien life deviated from branch, we would have common ancestor

B: An independent origin of life would belong on a completely different tree of life

Question 2

What did Carolus Linnaeus do?

Answer 2

System of taxonomy based on resemblences

Question 3

What is the Linnean System?

Answer 3

Generate two-part scientific name called binomial

First part is genus- level of hierarchy of species
Second part is specific epithet- unique for each species with genus

Question 4

What is homology?

Answer 4

Similarity due to shared ancestor

Question 5

What is analogy?

Answer 5

Similarity caused by evolutionary pressures resulting from exposure to similar conditions or adaptation pressures, meaning organisms do not share common ancestor

Question 6

What is Cladistics?

Answer 6

The part of taxonomy that groups organisms by common descent

Question 7

What is Clade?

Answer 7

A group of species that includes an ancestral species in all of its descendants

Question 8

What are evolutionary relationships traditionally based off of?

Answer 8

Morphology

Question 9

What are modern phylogenetic trees based on?

Answer 9

Genetic information, Molecular Systematics

Question 10

What are the three domains?

Answer 10

Bacteria, Archaea, Eucarya

Question 11

What is the Phylogenetic Tree of Life?

Answer 11

A powerful reference as we seek to understand life across the universe

Framework for exploring the evolution and interconnectedness of terrestrial life

Fundamental reference database for evaluation of possible life beyond Earth

Question 12

What does a phylogenetic tree of life show?

Answer 12

A variety of groups of organisms associated with each other

Question 13

What is Ribosomal RNA

Answer 13

Responsible for reading the order of amino acids and linking amino acids together

Creates peptide bonds between amino acids in polypeptide chain

Question 14

What is the purpose of building trees using DNA?

Answer 14

Find part of DNA that doesn’t change much over time

The closer two organisms are as relatives, the smaller the number of changes that would have occurred

Question 15

What causes mutations to generate changes in the genetic code?

Answer 15

Errors in DNA replication

Exposure to agents that damage DNA

Question 16

What are the three types of mutations?

Answer 16

Transversion- purine mutates into pyrimidine
Transition- purine into other purine
Insertions/Deletions

Question 17

What does more deviation in DNA sequences mean?

Answer 17

Greater evolutionary distance

Question 18

Why are phylogenetic trees useful?

Answer 18

For classification and ordering
To test scientific hypothesis

Question 19

How can we use trees to test where humans originated?

Answer 19

Changes in rRNA are too few in the last 3 million years of human evolutions

Mitochondrial DNA changes faster to resolve changes in human lineage

Question 20

What are the complication in building the universal tree with horizontal gene transfer?

Answer 20

The movement of genetic material between organisms like endosymbiosis is common in prokaryotes and complicates the tree of life

Question 21

What is transformation?

Answer 21

Prokaryotes take up naked DNA from environment

Question 22

What is transduction?

Answer 22

DNA transfer into a microbe through an agent such as a bacteriophage

Question 23

What is conjuction?

Answer 23

Genetic information transferred between microorganisms

Donor cells transfers info through pilus

Question 24

What is LUCA?

Answer 24

The last universal common ancestor

Question 25

What does it imply if the genes are found in all three domains?

Answer 25

The duplication occurred before the domains diverged

Question 26

What did Carl Woese infer?

Answer 26

The tree of life is rooted in bacteria with a later divergence between archaea and eukaryotes

Question 27

What did early analysis of the tree of life show?

Answer 27

Deepest branching organisms were heat-loving

Question 28

What was LUCA?

Answer 28

An anaerobe that lived from gasses

It used the most simple and ancient method of CO2 fixation called the aceytal-CoA pathway

It had a reverse gyrase, an enzyme typical of thermophiles

Question 29

What do the genes that trace to LUCA, ancient biochemical pathways, and aqueous reactions of CO2 with iron and water seem to converge on?

Answer 29

Similar sets of simple, exergonic chemical reactions occur spontaneously at hydrothermal vents. LUCA was rooted in rocks.

Question 30

What are phylogenetics?

Answer 30

The study of evolutionary relationships among groups of organisms