Lecture 2 - Life

Question 1

What are the step of the origins of life

Answer 1

1. Abiotic synthesis of small organic molecules
2. Formation of macromolecules from monomers
3. Formation of protocells which…
   a) reproduce (fission and/or budding)
   b) process energy
4. Origin of self-replicating molecules and systems (leads to inheritance and selection)

Question 2

Explain the abiotic synthesis of small organic molecules

Answer 2

During the early years of the earth, the first small organic molecules like CO2, NH3 were physically formed within the atmosphere.

In terms of energy, these reactions were caused by UV rays, lightning and volcanoes

Question 3

What are protocells

Answer 3

lipid-bound droplets with internal chemistry different from environment (origin of membrane)

Question 4

What is evolution

Answer 4

the process of change that has transformed life on Earth from its earliest beginning to the diversity of organism living today

Question 5

Number of species identified vs how many hypothesized to exist

Answer 5

• > currently around 1.8 million species have been identified
• > estimates range from 10-100 million species
• > around 99% of the earths species have gone extinct

Question 6

Explain the tree of life

Answer 6

Developed by Darwin

• > has a common ancestor

Tips = Organisms

Nodes = Common ancestors

Question 7

Characteristics of tree of life

Answer 7

• > trees are usually incomplete (usually include extanct species)
• > usually only include taxa (species, families,etc.) being discussed in that context and at that level

Question 8

Macroevolution

Answer 8

major evolutionary change; the history of life is punctuated by key innovations and other major events

Question 9

Major events of the history of life (macroevolution)

Answer 9

• > origin of organelles and novel designs (i.e. mitochondria, feathers, seeds)
• > Evolutionary trends (i.e. increasing brain size in hominoids, loss of hind limbs in whales)
• > adaptive radiation (process in which organisms diversify rapidly from an ancestral species into a multitude of new forms. i.e. so many types of birds)

Question 10

How are key innovations noted in a Tree of Life

Answer 10

• > KI are typically noted along branches of trees as if they magically appear

Question 11

How do Key innovations work in terms of evolution

Answer 11

• > KI evolve over many generations as progressive changes in a structure
• > Darwin said that many “small” changes persisting over generations can become big changes

Question 12

How can we identify the history of life

Answer 12

• > Fossil record
• > Relative dating

(the science of determining the relative order of past events i.e., the age of an object in comparison to another)

Question 13

Explain the fossil record

Answer 13

• > a fossil is a remnant or impression of an organism from the distant past
• > found mostly in sedimentary rocks
• > they’re rare (have to die at the right time and place, survive destruction, has to be found)
• > useful as historical record only if dated

Question 14

relative dating

Answer 14

• > the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age (i.e. estimated age)
• > sedimentation occurs in layers called strata
• > younger sediments superimposed on older ones

Question 15

sedimentation

Answer 15

the process of settling or being deposited as a sediment.