Origins of life

Question 1

How did the Earth form?

Answer 1

The Earth formed about 4.6 billion years ago due to a bombardment of huge chunks of ice and rock left over form the formation of the solar system this generated heat.

Question 2

What did this heat cause?

Answer 2

• Caused Ice to form vaporized water
  -Prevented sea formation for 4 billion years

Question 3

What was noteworthy about the Earth’s atmosphere at the time?

Answer 3

little to no oxygen but had lots of water vapour and compounds (released by volcanic eruption)
- e.g. nitrogen and its oxides, carbon dioxide, methane,
ammonia, hydrogen.

Question 4

How did the first living cells form?

Answer 4

Scientists hypothesized that chemical and physical processes could
have produced simple cells through a sequence of four main stages:
1. Abiotic (non-living) synthesis of small organic molecules.
(e.g. amino acids and nitrogenous bases)
2. Small molecules joined forming macro molecules (lipids, carbohydrates, proteins
and nucleic acids).
3. Packaging of these molecules into Protocells
(Vesicle droplets with membranes that maintained an internal chemistry different
from that of their surroundings)
4. Origin of self-replicating molecules that eventually made inheritance possible.
e.g. (RNA) because DNA requires a range of enzymes/proteins for its replication

Question 5

What are the three theories of autogenesis

Answer 5

1) Primordial soup Hypothesis
2) Hydrothermal vent theory
3) Meteorite Theory

Question 6

What do these theories try to explain?

Answer 6

Where/How organic molecules came about, forming the building
blocks required for the early cell (Protobionts) formation.
- Try to describe what the conditions were like when the first life
forms originated.

Question 7

Differences between eukaryotic and prokaryotic cells

Answer 7

see table

Question 8

Similarities between eukaryotic and prokaryotic cells

Answer 8

Enclosed by a plasma membrane
Cytoplasm which contains other cell components
Have genetic material
Have ribosomes
undergo reproduction/cell division

Question 9

Similarities between mitochondria and chloroplasts

Answer 9

Both have small circular DNA
Have 70s ribosomes
Replicate via binary fission
Both have inner and outer membranes