Genomstruktur og genomstudier i planter

Question 1

Explain the difference between autopolyploidy and allopolyploidy.

Answer 1

Autopolyploidy is a doubling of the entire chromosome count in an organism within a species.
Allopolyploidy is a combination of chromosomes from two or more species that gives rise to a
new species.

Question 2

What could be the reasons why so many of the crops are polyploid?

Answer 2

Perhaps plants tolerate genome duplication better than animals because they have inherently more flexible body plans than animals, and can more easily cope with any gross anatomical changes that might accompany it. Polyploids generally have larger cells and organs.

Question 3

his image shows the C-banding of the chromosomes in barley. What are the reasons why
most of the marked areas are concentrated around the middle of the chromosomes?

Answer 3

C-banding marks one with constitutive heterochromatin (which is inactive and tightly packed
DNA) and in the area around the centromer there is a lot of heterochromatin.

Question 4

What is the most important role of physical maps in genome sequencing projects?

Answer 4

To help place sequence fragments (contigs and scaffolds) in the correct order and with proper
spacing along the chromosomes.

Question 5

How does the recombination rate vary along a typical chromosome in plants?

Answer 5

There is a lot of recombination happening in the telomeric regions, while there is little
recombination in the area around the centromere.

Question 6

Analyses of the genome sequence of bread wheat show that there are a total of 107,891 active
protein-coding genes in bread wheat (estimate) while analyses of the corresponding genome
sequence for barley show 39,734 active genes. What could be the reasons why this difference is
so great?

Answer 6

Barley is diploid, while bread wheat is allo-hexaploid. The wheat genome generally has 3 copies
of each gene found in barley.