Lecture 3

Question 1

What was Earth’s early atmosphere like?

Answer 1

A lot of methane
A lot of CO2
Little to no oxygen
High temp
A lot of lightning and volcanic eruptions which caused a lot of energy
No ozone layer

Question 2

What the relation between the Earth’s early atmosphere and organisms?

Answer 2

The Earth’s early atmosphere promoted spontaneous reactions and thus the formation of carbon compounds
Living organisms changed spontaneous conditions

Question 3

How did RNA come about?

Answer 3

The Earth’s crust contains metals which acted as catalysts and allowed for the assembly of polymers such as RNA from biomolecules

Question 4

What is likely to be the first genetic material?

Answer 4

RNA:
It can store genetic information
Self-replicating
Can act as an enzyme
More prone to mutations which could lead to advantages

Question 5

How may a phospholipid bilayer have come about?

Answer 5

Biomolecules would have been surrounded by phospholipids to form a phospholipid bilayer

Question 5

What is LUCA?

Answer 5

Last universal common ancestor of cells

Question 6

How would early stage cells have turned into LUCA?

Answer 6

Over time, phospholipids are able to surround RNA which leads to the formation of cells
Over time, RNA would become DNA as it is more stable
Lipid bilayers would spontaneously form vesicles

Question 7

What is the endosymbiotic theory?

Answer 7

Anaerobic cell engulfs an aerobic cell/bacteria, this became specialised and become a mitochondria
The anaerobic cell can now carry out oxidative phosphorylation and generate energy and the aerobic cell can be protected

Question 8

What are protozoans?

Answer 8

Single-celled eukaryotes
Mostly live in aquatic environments
Can cause disease

Question 9

What are possible examples of early multicellularity?

Answer 9

In algae:
Somatic cells on the outside and germ cells in the middle, germ cells will proliferate and become surrounded by somatic cells which will burst and release volvox colonies to make more colonies
In slime moulds (Dictyostelium discoideum):
Slime moulds will secrete agents to attract other slime moulds to form a colony, the colony will collapse down into a ‘naked slug’ shape and an upwards projection will be sent out to form a ‘head’ and a ‘base’

Question 10

What are retroviruses?

Answer 10

They are a type of virus that can change their RNA to DNA

Question 11

What are lentiviruses?

Answer 11

They are a type of virus that can remain dormant until the immune system has weakened