Nucleic acids and the origins of life

Question 1

What are nucleotides?

Answer 1

They are building blocks for nucleic acid polymers and specialized for the storage, transmission, and used of genetic information

Question 2

How are nucleotide formed?

Answer 2

Base + Sugar (ribose and deoxyribose) = Nucleoside + phosphate = Nucleotide

Question 3

Cytosine, Thymine and Uracil are all examples of?

Answer 3

Pyrimidines

Question 4

Adenine and Guanine are examples of what?

Answer 4

Purines

Question 5

Other functions of Nucleotides?

Answer 5

ATP and GTP
cAMP

Question 6

How are nucleotides linked together? what direction does it grow in?

Answer 6

Phosphodiester linkages, Carbon 3’ in one sugar to carbon 5’ in another sugar

5’to3’ direction

Question 7

What is the structure of RNA?

Answer 7

Single stranded, unique secondary structures through base pairing

Question 8

What is the function of RNA?

Answer 8

(1) structural and functional roles - catalytic
(2) information role in specifying a sequence of amino acids in a polypeptide

Question 9

What is the structure of DNA?

Answer 9

double stranded, anti-parallel strands, double helix

Question 10

What is the function of DNA?

Answer 10

(1) DNA can reproduce itself
(2) DNA sequences can be copies into RNA

Question 11

What is the importance of complementary base-pairings?

Answer 11

Purines pair with pyrimidines by hydrogen bonds.

Question 12

Explain how and when the small molecules of life likely originated?

Answer 12

(1) Small molecules of life came from space
- In 1969 fragments of meteorite were found to contain molecules unique to life
(2) chemical evolution
-conditions on primitive earth led formation of simple molecules which then lead to formation of life forms

Question 13

What condition in which polymers might have been synthesized?

Answer 13

Abiotic

Question 14

what is the RNA world hypothesis

Answer 14

Proposes that life on Earth began with a simple RNA molecule that could copy itself without help from other molecules

Question 15

How is the RNA world plausible?

Answer 15

It can store genetic information and catalysed chemical reactions

Question 16

What is the concept of RNA carrying information and acting as a catalyst?

Answer 16

According to the RNA world hypothesis, RNA both (1) stored genetic information and (2) catalysed chemical reactions in primitive cells

Question 17

How did proteins evolve?

Answer 17

Such tRNA like adaptors for amino acids could have arisen in the RNA world, making the beginnings of genetic code. Once coded proteins synthesis evolved and the greater versatility of proteins, the transition to a protein dominated world could proceed.

Question 18

Why change from RNA to DNA for information storage?

Answer 18

If there is a mistake in the sequence DNA can correct the mistake in the mutation. Reducing error frequency in replicating DNA.

Question 19

what is the central dogma of molecular biology?

Answer 19

DNA ⇄ RNA –> Protein
Information ⇄ Information transfer –> Catalysis

Question 20

Define ‘living state’?

Answer 20

Non-equilibrium steady-state in organisms