L17: Evolution of Life

Question 1

What was the main theory for the origin of earth and what are the steps?

Answer 1

Formation of earth (big bang)
Stable Hydrosphere
Prebiotic chemistry (soup)
Pre-RNA world
RNA world
First DNA
LUCA

Question 1

What are the major transitions in the evolution of like?

Answer 1

RNA as gene and enzyme - DNA protein
Prokaryotes - Eukaryotes
Primate societies - Human societies

Question 2

What is an example of an experiment used to replicate the origin of life?

Answer 2

Miller-Urey Experiment

Question 3

What took place in the Miller-Urey experiement?

Answer 3

A heat source and water was used to replicate lava and water, then gases that provided the composition of the atmosphere were used which produced nucleotides

Question 4

What were the downfalls of the Miller-Urey experiment?

Answer 4

It was done in a reducing environment, considered unlikely
The flask (silica) contributed towards the organic products

Question 5

What did other experiments use to replicate the beginning of earth?

Answer 5

-A neutral atmosphere (complex gases)
-Arrival from space - meteorites
-Mineral (clay) catalysts and adsorbents - act as templates
-Deep sea vents - mineral rich water, sites of abundant life

Question 6

What is the progenote?

Answer 6

An organism still in the process of evolving the relationship between genotype and phenotype

Question 7

What was the process of the creation of the progenote?

Answer 7

Prebiotic soup - Self-replication - Cellularization - DNA genome - Invention of TLN - progenote

Question 8

What was the hypothesis C.Woese and G.Fox put forward?

Answer 8

That the LUCA was a progenote

Question 9

Why is RNA thought to have similar function to proteins?

Answer 9

As it can fold which provides different functions

Question 10

What came first in evolution?

Answer 10

RNA

Question 11

What is the main functional RNA?

Answer 11

mRNA

Question 12

Which RNA has catalytic activity?

Answer 12

rRNA - for protein synthesis

Question 13

What is the main proof that there was an RNA world?

Answer 13

The ribosome - removal of the protein still allows activity of the ribosome

Question 14

What is the difference of RNA to DNA?

Answer 14

-Uracil instead of Thymine
-2’-OH making it chemically unstable but increases flexibility

Question 15

Why is the instability of RNA advantageous?

Answer 15

As it allows folding of ssRNA into complex structures

Question 16

What are the features of RNA?

Answer 16

-Stores genetic information
-Scaffolding
-Carries genetic info
-Recognition
-Catalytic activity
-Template
-Structure

Question 17

What are examples of RNA storing genetic information?

Answer 17

In RNA viruses like HIV

Question 18

Where is catalytic activity used in RNA?

Answer 18

In ribozymes

Question 19

What are the different ways RNA can fold?

Answer 19

-Three-nucleotide bulge
-Four-stem junction
-Pseudoknot
-Hairpin loop

Question 20

What is an example of a natural ribozyme?

Answer 20

A ribozyme from viroids: replicates in plastids which infects plants by cleaving long RNA required for replication

Question 21

What is another use of RNA catalysis?

Answer 21

Self-splicing introns e.g. paramecium

Question 22

What are examples of the biochemical reactions catalysed by ribozymes?

Answer 22

-Peptide bond formation in p.synthesis
-RNA cleavage and RNA ligation
-DNA cleavage
-RNA splicing

Question 23

What are most of the biochemical reactions catalysed by ribosymes?

Answer 23

Artificial as they are done in vitro

Question 24

What is an example of an artificial of ribozymes catalysing biochemical reactions?

Answer 24

Autophosphorylation using ATP

Question 25

What is the process of ribozymes being used in autophosphorylation in vitro?

Answer 25

dsDNA is transcribed into RNA and is folded, ATP is added and the phosphate binds to one of the folded RNA molecules, the molecule is then separated

Question 26

How does RNA enzyme mediate its own replication?

Answer 26

By using the catalytic site to make more of itself

Question 27

What is the model of the order of events from complex organic molecules?

Answer 27

RNA world (RNA) - RNP world (protein) - LUCA (DNA)

Question 28

What are the main arguments for the RNA primordial world?

Answer 28

-RNA polymerisation and replication can take place in vitro
-Genome of some viruses is based on RNA
-RNA molecules more complex than DNA (more functions)
-RNA can mediate catalytic reactions (Ribozyme)
-RNA is important in all organisms (particularly in protein synthesis)
-Synthesis of deoxyribose required ribose contained in RNA
-Nucleoside function as coenzymes is important to enzymes

Question 29

What is the progenote model?

Answer 29

RNA being self-replicating (RNA world)
RNA leads to protein-based systems
DNA is self-replicating leading to RNA and proteins