Genetics first

Question 1

Describe the RNA world hypothesis

Answer 1

Idea that RNA can work as a catalyst and pass genetic information

Question 2

What 3 types of ribosomes support the RNA world hypothesis?

Answer 2

1. RNA Ribozymes promote key reactions
2. Riboswitches turn genes on and off
3. Coenzymes promote the citric acid cycle

Question 3

What are the 3 key ssumptions of an RNA world?

Answer 3

1. RNA at one time stored genetic information
2. RNA replication follows the same rules as DNA replication
3. Ancient RNA provided the same catalytic roles as proteins

Question 4

Give a pro and a con of the RNA world hypothesis

Answer 4

Pro: RNA is ancient and found in everything
Con: RNA is complex and would not have formed randomly

Question 5

Give 2 examples of possible pre-RNAs

Answer 5

1. Therose Nucleic Acid (TNA) uses 4-C therose, which is more likely from the prebiotic soup however has not yet been synthesized abiotically
2. Peptide Nucleic Acid (PNA) has RNA bound bases bond on an amino acid backbone. Amino acids are easier to produce

Question 6

What is the major flaw of the PNA/TNA world hypothesis?

Answer 6

Neither sugars nor amino acids self-organise

Question 7

How could PAHs play a role in the construction of RNA?

Answer 7

• PAHs are abundant in pre-biotic molecules an have the ability to self organise and stack
• Hypothesized that they could bind to small flat molecules, building up chains of RNA
• Spacing between PAH’s is 0.34 billionths of a metere, exactly the dame spacing as between bases in RNA
  HOWEVER: not tested yet and hard to get

Question 8

Who made a self-replicating DNA molecule and what was it made of?

Answer 8

Guenter von Kiedrowski

six nucleotide sequence CCGCGG (had to be fed fresh C and G)

Question 9

What recent problem has arisen for the RNA world hypothesis?

Answer 9

• Believed that RNA nucleotides would have mixed with DNA backbones creating “heterogenuous” strands, and that these ‘chimeras’ were an intermediate step
• However, research has shown that these arrangements are unstable so did DNA and RNA arise in tandem?