lecture 02

Question 1

1. What can genomes help us understand?(2)

Answer 1

Genomes can help us understand ourselves as individuals and our
relationships with all other organisms that exist in life

Question 2

a. How can we achieve question 1?

b. What does it include?(4)

Answer 2

a.To achieve that, we must integrate several data streams, including:
b.- genome sequences
-RNA and protein expression patterns
- the spatial organization of individual macromolecules, their complexes,
organelles, entire cells, tissues and bodies
- regulatory networks, the internal structure and logic of adaptive control
systems

Question 3

a. What suggestion was proposed y Salvador Luria?(1)

b. What idea did the author come up with in addition to Lurias proposal?(2)

Answer 3

a.S.E. Luria
to determine common features of all life one should not try to survey everything, but, rather, identify the organism most different from us and see what we have in common with it

b.complementary idea
take the most closely related organisms and identify the differences
- human vs E. coli (common heritage); human vs chimps (4% difference)

Question 4

How are the 2 proposals different but related?

Answer 4

one seeks to find (genetic) similarities between very different organisms (e.g. human vs E. coli), whereas the latter proposal is to find differences between closely-related organisms (e.g. human vs chimpanzees).

Question 5

a. What is the C-value? What does the letter C refer to?

b. Pg=?

Answer 5

a. C-value – the amount of DNA (measured in pg) in a haploid cell, thus, a gamete
- >the letter C refers to the constancy of the amount of DNA per cell in aspecies

b. pg = picograms or 10-12 g.

Question 6

a. What correlation exists?
b. How much DNA do prokaryotes have per cell compared to eukaryotes?
c. Among eukaryotes which has less than mammals?

Answer 6

General correlation between complexity of organism and amount of DNA per cell (Fig. 7.3 & Table 7.1)

b.prokaryotes have less DNA per cell
than eukaryotes

c. among eukaryotes, yeast has less
than mammals

Question 7

a. What is the deviation for the C value?(1) What does this mean?
b. List the 3 notable examples mentioned?(3)
c. What formula do we use to convert between amount of DNA in pg and genome size in bp?

Answer 7

a.Deviations: (C-value paradox)
What this means is that sometimes less complex organisms have much more DNA per cell than
complex organisms

b. 3 examples of this
-Amoeba dubia genome is 200 times
larger than the human genome
- marbled lungfish (Protopterus
aethiopicus), a closer relative, is 43
times as large as humans
-clivia genome is about six times larger than humans

c.(DNA in pg = genome
size in bp/0.978 x 109 bp, see Dolezel et al 2003)

Question 8

Discuss the 2 points on Why are there differences in genomic sizes between different organisms?(3)(4)

Answer 8

1. most of the human genome does not encode protein or RNA
   - regions of genomes without known function are often called ‘junk DNA’
   - however, unknown function does not mean no function
   - also, not all regions are transcriptionally inert/inactive – some, encode novel types of RNA molecules, mostly involved in regulatory processes
2. further, amount of space between genes affect the rate of crossing over
   (as well as recombination!) and, thereby, rates of evolution
   -large amount of repetitive sequence between our genes enhance recombination rates by promoting homologous recombination
   -change in gene sequences allude to evolution taking place; rate of evolutionary change is a characteristic of a species that is certainly subject to selective pressure
   - features of the genome that affect rate of evolution cannot be dismissed entirely as junk
   -overall, different amounts of DNA in genomes provide different ‘theatres’ for evolutionary play