Beginning of Life and Synthetic Biology

Question 1

What did ‘fertile atmosphere’ experiments generate?

Answer 1

Amino acids
Bases - Adenine, Guanine, Uracil
ATP, Coenzyme A
Ribose

Question 2

What can NH3 be made from?

Answer 2

(FeS) + N2 + H2O

Question 3

What does HCN hydrolysis provide?

Answer 3

All of the nucleotides

Question 4

What can aldehydes be made from?

Answer 4

CO2 and H2O

Question 5

What are polyphosphates made from?

Answer 5

Meteor impacts in the oceans at 2000 degrees C

Question 6

Why was primeval broth view experimentally criticised?

Answer 6

Too much H2
CH4, CO minor components
CO2 and N2 major components
‘Prebiotic soup’ - oceans - molecules too dilute to react

Question 7

When was the RNA world predicted to be?

Answer 7

3.5-4 million years ago

Question 8

What is the simple meaning of being living?

Answer 8

Anything that replicates is living

Question 9

Which rRNA makes only RNA?

Answer 9

23S rRNA

Question 10

What is special about the 23S RNA intron?

Answer 10

It splices itself out without any help from proteins

Question 11

What does the 23S RNA intron need to splice itself out?

Answer 11

Free 3’ hydroxyl group of guanine nucleotide / nucleoside which attacks 5’ end of intron

Question 12

What can the tetrahymena intron do?

Answer 12

1) Make and break bonds between tRNA and amino acid

2) Generate a poly-cytosine nucleotide strand, make and break phosphodiester bonds between nucleotides

Question 13

What did Carl Woese find (1987)?

Answer 13

rRNA genes more conserved than ribosomal protein coding genes

Question 14

What does rRNA provide and what does the protein provide?

Answer 14

The catalytic component for protein elongation, proteins provide scaffold

Question 15

What does montmorrillonite clay do?

Answer 15

Attracts nucleotides promoting polynucleotide formation even in dilute solutions
Promotes vesicle assembly - membranes and encapsulation

Question 16

What does RNA need to replicate?

Answer 16

One ribozyme, plus one complementary copy to act as a template

Question 17

Why are errors in copying necessary?

Answer 17

For evolution to take place

Question 18

What stabilises replicase RNA?

Answer 18

Amino acid (+ charge) - Selection for the first tRNA

Question 19

What stabilises the RNA?

Answer 19

Amino acids - beginning of RNP world

Question 20

What was the initial ‘tRNA’ function in?

Answer 20

Replication

Question 21

What do many retroviruses have?

Answer 21

3’ tag with terminal CCA - signal for replication

Question 22

What identifies a molecule as a substrate for replication and where does replication start?

Answer 22

3’ lops plus terminal CCA

Replication initiates at first C of CCA

Question 23

What do stem loops do?

Answer 23

Provide catalytic potential

Provide dsRNA regions, so complimentary RNA strands formed

Question 24

What is the ‘iron-sulphur world’ theory?

Answer 24

Metal sulphides (FeS) catalysed reactions to generate amino acids under high pressure and intense heat (up to 250 degrees)

Question 25

What is carbonyl sulphide (COS) and what does it do?

Answer 25

Volcanic gas
In the presence of L-phenylalanine mediates the condensation to dipeptide. Mediates mixed peptide condensation with metal sulphides from single mixture of L, F, S, A, Y

Question 26

What came first: translation or replication?

Answer 26

Translation

Question 27

Why did RNA world give rise to DNA world?

Answer 27

DNA is more stable, better replicator

Question 28

Which enzymes change RNA to DNA?

Answer 28

Ribonucleotide reductase: Ribose to deoxyribose

Reverse transcriptase: RNA to DNA

Question 29

What are the three classes of ribonucleotide reductase?

Answer 29

Aerobic
Independent of O2 but cobalt-dependent
Anaerobic