Lecture 2: Origin of LIfe

Question 1

protoplanetary disk

Answer 1

-large rotating cloud of dust, rocks, and gas

Question 2

formation of our sun

Answer 2

-presuure within the central mass of the protoplanetary disk triggers nuclear fission

Question 3

protoplanet

Answer 3

-a large body of matter in orbit around the sun or a star and thought to be developing into a planet

Question 4

precambrian supereon

Answer 4

• so vast it’s considered a supereon

- found early multicellular life

Question 5

paleozoic era

Answer 5

-covers time of soft-shelled mussels and hardshelled organisms to land being dominated by sophisticated reptiles and plants

Question 6

mesozoic era

Answer 6

• first mammals
• age of reptiles (dinosaurs)
• ends with K-T extinction

Question 7

cenozioc era

Answer 7

-age of mammals (including humans)

Question 8

early hadean eon

Answer 8

• no oceans
• no O2 in atmosphere
• no protective atmosphere
• lots of molten lava
• no life

Question 9

late hadean eon

Answer 9

• no ozone layer to protect against UV rays
• oceans form as planet cools and clouds form
• no life

Question 10

archean eon

Answer 10

• atmosphere forms from:
  
  • ->gas released by volcanoes
  • ->astroidal bombardment creates crack on Earth and steam escapes from cracks
• originally had methane, CO2, water, in atmosphere
• any free oxygen had to be bound to hydrogen or other elements

Question 11

which eons were located in precambrian supereon?

Answer 11

• hadean
• archaean
• proterozoic

Question 12

unicellular vs multicellular

Answer 12

U: single-celled, less complex, mainly bacteria
M: multiple cells, more complex, more developed organisms

Question 13

stromatolites

Answer 13

-layeredbands of fossilized bacteria (cyanobacteria)

Question 14

bacterial fossils

Answer 14

-in fossil stromatolites, the layers that are formed as biofilms of cyanobacteria die and others take their place

Question 15

archean fossils

Answer 15

-trace fossil: pathway in dirt or terrain that indicates movement

Question 16

trilobites

Answer 16

-very first of the hard-shelled organisms

Question 17

archeocyathids

Answer 17

• vsrious Cambrian sponge-like animals

- believed to be the base of the animal tree

Question 18

1st land plants

Answer 18

• carpet moss

- paleozoic era

Question 19

1st land animals

Answer 19

-early amphibian tetrapod; fish evolved legs and started to walk on land

Question 20

permian extinctinon

Answer 20

• aka The Great Dying
• up to 96% of all life went extinct
• only mass extinction of insects but largestin history
• O2 levels drop rapidly
• ends Paleozoic Era

Question 21

age of repitles

Answer 21

• dinosaurs appear

- mesozoic era

Question 22

1st mammals

Answer 22

-morganucodon watsoni

Question 23

K-T extinction event

Answer 23

• catastrophic event occurred
• asteroid impact couldve triggered increased volcanic activity
  
  • ->more dust and ash in the air dec. sunlight available hindering photosynthesis thus mass destruction of earth’s ecology

Question 24

K-T boundary

Answer 24

• thin band of sediment that only non-avian dinosaurs are formed under (fossils could be found)
• found on mountains

Question 25

geologic clock

Answer 25

• shows the history of time in a typical clock face

- helps us revisualize the passage of time

Question 26

first step to form life

Answer 26

-abiotic synthesis of organic materials

Question 27

second step to form life

Answer 27

-formation of polymers–> chains of things to form bigger things (occurs spontaneously)

Question 28

third step to form life

Answer 28

• formation of protobionts

- hydrophillic heads and hydrophobic tails, but the heads attacht to water and chemicals

Question 29

fourht step to form life

Answer 29

• origin of hereditary material
• 1st life probably in RNA world can be formed abiotically, can replicate itself, zinc around–> forms clay DNA cannot replicate itself, has catalytic properties–> can be a catalyst and also carry genetic info.

Question 30

Miller and Urey’s experiment

Answer 30

• trying to prove that the conditions that existed on primitive Earth were capable of leading to organic compounds
• used water, H2, CH4, NH3 which were the building blocks of life
• their results proved that the assumed conditions of earth can lead to organic compound and eventually to life

Question 31

monomer

Answer 31

• the single units that make up polymers

- three types are: simplesugars, nucelotides, and amino acids

Question 32

polymer

Answer 32

-a long molecule consisting of many similar or identical building blocks linked by a dehydration rxns

Question 33

protobionts

Answer 33

-systems that are considered to have possibly been the precursors to prokaryotic cells

Question 34

four reasons we think there was originally a RNA world

Answer 34

1) easily forms abiotically than DNA
2) can replicate itself, more likely in the presence of zinc
3) has hereditary info
4) has catalytic properties (can act like an enzyme)

Question 35

four reasons we think there was originally a RNA world

Answer 35

1) easily forms abiotically than DNA
2) can replicate itself, more likely in the presence of zinc
3) has hereditary info
4) has catalytic properties (can act like an enzyme)

Question 36

viroids

Answer 36

• raw bits of RNA
• causes diseased plants
• may be the clue to the RNA world and responsible for modern life

Question 37

cyanobacteria

Answer 37

• live on stromatolites
• first prokaryote
• believed to be 1st organisms bc they can perform photsynthesis

Question 38

morganucodon watsoni

Answer 38

• one of the first mammals
• rat looking rodent
• mezoic era

Question 39

the importance of clay

Answer 39

• clay is positively charge and rich in iron and zinc
• monomers all have negatively charged portions and are attracted to the clay and that might’ve put them in close enough proximity to form chains