3a. Genome structure content variation

Question 1

The ‘C-value’ paradox

Answer 1

Genome size does not correlate with an organism’s complexity. It is not the number of genes, but the proportion of TEs that accounts for the main differences in genome size among species.
(Grasshopper has a less selective pressure, and because of than can have more ‘junk’ DNA)

Question 2

Pseudogenes

Answer 2

are nonfunctional segments of DNA that resemble functional genes – they can’t express their properties

Question 3

Where do new genes come from?

Answer 3

• Gene duplications
• Repetitive sequences
• Amplification of transposons (= a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell’s genetic identity and genome size)

Question 4

Polyploidy

Answer 4

more than 2 copies per chromosome (more than 3 copies lethal in humans)

Question 5

Endopolyploidy

Answer 5

replication without cell division

Question 6

Autopolyploid

Answer 6

the genome consists 2 copies of the diploid genome = tetraploid
(occurs when a polyploid offspring is derived from a single parental species (usually via self fertilisation))

Question 7

Allopolyploid

Answer 7

diploid set of chromosomes from 2 genetically different parents
(occurs when a polyploid offspring is derived from two distinct parental species)

Question 8

Paleo- polyploidy

Answer 8

massive gene duplication at one time using a molecular clock

Question 9

HOX genes

Answer 9

a family of transcription factors, are major regulators of animal development (where come the head, legs, eggs)