Lecture 3 History of life on earth

Question 1

Hypothesis

Answer 1

Physical and chemical processes could have produced simple cells

Question 2

RNa Hypoothsis 1st step

Answer 2

The biotic synthesis of small organic molecules

Question 3

RNA Hypothesis 2nd step

Answer 3

Joining of these small molecules into macromolecules

Question 4

RNA Hypothseis 3rd step

Answer 4

packaging of molecules into “protocells”

Question 5

Rna hypothesis 4th step

Answer 5

the origin of self-replicating molecules
- first genetic material probably RNA because it can from 3d shape and can self replicate

Question 6

Monomoers

Answer 6

single
amino acid
nucleotides
sugars

Question 7

poly

Answer 7

Chain
proteins
carbons
nucleic acids (Dna, RNA)

Question 8

Hydrothermal vents

Answer 8

break in earths crust, bottom of the ocean, release geothermically heated water

Question 9

Vents and early life

Answer 9

release hot water with high pH (basic)
surrounded by cool water ( acidic)
vents are made of porous rock
ph difference gives rise to proton gradient = main source of energy

Question 10

Key event in life’s history

Answer 10

paleozoic (542-251 mya)
Mesozoic ( 251-655 mya)
Cenozoic ( 655-today)

Question 11

1. First unicellular organisms

Answer 11

3.5 bya
Stromatolites layered rocks shows earliest prokaryotes

Question 12

2. Oxegen revolution

Answer 12

atmospheric o2 gas comes from living organisms which is a byproduct of phtosyncthesis which becomes saturated by the ocean and the ocean releases oxygen to the atmosphere.

Question 13

3. First eukaryotic : endosymbiosis

Answer 13

Some euk organelles arose when small props began living inside larger cells

Question 14

4. First multicellular organisms

Answer 14

some euks are multicellular
allows for increased diversity
descendants include plants, animals, fungi

Question 15

5. Cambrian explosion

Answer 15

many animal groups appear “suddenly”
increased predators = defensive mechanisms emerged

Question 16

6. Colonization of land

Answer 16

adaptations include :
1) prevent dehydration
2) allowing for reproduction
most succesful animals are the anthropoids

Question 17

Mass extinctions

Answer 17

loss of large # of species due to global environment change
5 in last 500 mya
50 % of marine species wiped out
cretaceous –> 50% of plants , marine , terrestiral , dino were wiped out

Question 18

6th mass extinction

Answer 18

100-100 x faster than usual
often coorelates with increawse in global temps
over in 100-1000 years

Question 19

Consequences of mass extinctions

Answer 19

change course of evolution
5-10 mya for biodiversity to recover

Question 20

adaptive radiation

Answer 20

follows mass extinctions
period of evo change during which orgs form new species filling in empty ecological roles

Question 21

Features shared by all cells

Answer 21

prokaryote- simple , small
euk- larger , complex
contain cytoplasm
ribosome transfer rna
carry out similar types of metabolism
dna is genetic material

Question 22

what make cells different

Answer 22

size
location of dna ( euk nuk, prok cyto)
membrane bound organelles ( euks only)
cell wall
ribosomes
cytoskeleton (euk)

Question 23

evidence for endosymbiosis

Answer 23

circular dna
mechanisms of growth / division
compnents of inner membrane
size

Question 24

Development of endosymbiosis

Answer 24

1) capture of bacterial cells (prokaryote) by archean cell
2) symbiotic relationship = more efficient energy production
3) bacterial cell lost ability to be free living= mitochondria + chloroplasts