origin of life

Question 1

how are the oceans and salt in them formed

Answer 1

water vapor condenses and falls as rain

salts added over billions of years as material eroded from continents

Question 2

Why first life likely formed in water

Answer 2

water protects from U-V radiation

Question 3

First cell =

Answer 3

anaerobic conditions

Question 4

how did first cell form

Answer 4

Spontaneous formation of monomers and macromolecules from chemicals in environment
** Only possible if no free O2
cell membranes form
C) nucleic acids pass on Genetic information

Question 5

monomer synthesis

Answer 5

we created organic monomers from non-living chemicals

Question 6

Miller and Urey - created “Early Earth Apparatus”

Answer 6

Archaean atmosphere
electrodes produce “lightning”
primordial pond in the bottom

Question 7

results of early earth apparatus/ monomer synthesis

Answer 7

12 of 20 most common amino acids synthesized + monomers

Showed monomers can form from non-living source

Question 8

Requirements for polymerization

Answer 8

energy source: lightning or geothermal vents
concentration: to bring materials together
tide pools/evaporation
clay

Question 9

clay

Answer 9

form platelets, they are very small, flat, with negative charge on surface

Question 10

cell membrane formation

Answer 10

phospholipids amphipathic
hydrophobic tails and hydrophilic head
formed spheres in water, hydrophobic tails protected on inside

Question 11

Protobionts/protocells

Answer 11

A) fatty acid spheres form naturally
B) Macromolecules & enzymes inside
C) reactions occur inside
D) Grow
E) divide 
F)selectively permiable
G) digest starch
H) store & release energy

Question 12

Sidney w. Fox and Aleksandr Oparin have demonstrated

Answer 12

that protobionts form spontaneously. They formed liposomes and microspheres, which have membrane structure similar to the phospholipid bilayer found in cells

Question 13

Are Protobionts Alive

Answer 13

No, they can’t replicate themselves

pass on their traits to offspring

Question 14

replication

Answer 14

process by which organisms make genetic copies of themselves

asexual or sexual reproduction

Question 15

origin of heredity

Answer 15

many different types of protobionts
those best able to accumulate organic molecules, grow, and divide become most common
but “competition” is useless unless traits can be passed on/inherited
need polymers that can replicate themselves: DNA and RNA

Question 16

nucleic acid reproduction/ RNA world hypothesis

Answer 16

RNA can assemble on its own (Zn catalyst)
Can replicate (make more copies)
Can pass on genetic info when cell divides

Question 17

earliest life forms

Answer 17

3.5 bya, prokaryotic bacteria, anaerobic, fermenters- use organic molecules for energy

Question 18

the first energy crunch

Answer 18

organic molecules become scarce
 competitive advantage goes to – 
organisms that can make their own food 
Photosynthesis
done by primitive cyanobacteria

Question 19

the process to get to photosynthesis

Answer 19

light-absorbing pigments (like chlorophyll) already present
chlorophyll rings form spontaneously
mutation causes e- to jump out
leads to Anaerobic cyclic psyn
Makes only a little ATP (no glucose)

Question 20

Aerobic Non-cyclic Photosynthesis

advantage and problem

Answer 20

some cyanobacteria evolved to use H2O as e- source
O2 released as a by-product
Advantage: glucose produced = storable energy
Problem: O2 toxic to anaerobic cells

Question 21

Earliest (Undisputed) Fossils =

Answer 21

Stromatolites

Question 22

Stromatolites

Answer 22

dome-shaped, layered structures
Up to 3.5 byo
consist of layers of bacteria
upper layers aerobic, photosynthetic
lower layers anaerobic
produce abundant oxygen

Question 23

formation of stromatolites

Answer 23

cyanobacteria form a mat on top of sediment
a new layer of sediment is deposited on top
bacteria grow up through new layer

Question 24

Stromatolites provide evidence for the

occurrence of

Answer 24

cyanobacteria in the fossil record.

Question 25

aerobic bacteria

Answer 25

some bacteria evolved antioxidants

allowed them to survive rising oxygen levels, others evolved to use oxygen in aerobic respiration

Question 26

Obligate anaerobe bacteria

Answer 26

restricted to refuges or go extinct

Question 27

The rise of cyanobacteria & build up of oxygen in atmosphere had three significant effects:

Answer 27

1) Aerobic photoautotrophs became producers that fuel the food chains of surface world
2) The first mass extinction
3) oxygen-rich atmosphere set stage for the multicellular life (aerobic respiration)

Question 28

eukaryotic cells

Answer 28

First well established fossils 1.7 bya
Mid-Proterozoic eon
Early protists
unicellular
with nucleus
100x larger than bacteria

Question 29

Origin of Nucleus & E. R.

Answer 29

In-folding of cell membrane
Similar to bacterial psyn membrane
Surrounded DNA
Formed ER

Question 30

Endomembrane system and nuclear envelope are

Answer 30

continuous

Question 31

organelles of the endomembrane system include:

Answer 31

the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, endosomes and the cell membrane.

Question 32

the endomembrane system definition

Answer 32

the set of membranes that form a single functional and developmental unit, either being connected directly, or exchanging material through vesicle transport.’

Question 33

Origin of Mitochondria & Chloroplasts

Answer 33

Endosymbiotic theory
Eukaryotic cells take in bacteria as endosymbionts
Aerobic Bacteria become mitochondria
Cyanobacteria become chloroplasts

Question 34

Evidence for Endosymbiotic Theory

Answer 34

Two membrane layers of 
Outer membrane like host cell
Inner membrane like a bacteria
Mito. & chloro. have their own DNA
Circular Chromosome 
Different genes than nucleus
Mito. & Chloro have own ribosomes &
Make own proteins 
Ribosomes like bacteria
Mito & Chloro grow and reproduce on own