Chromosome Structure

Question 0

Telomeres

Answer 0

• the G-heavy nucleotide repeats are synthesized by a special enzyme, telomerase, that contains an RNA template molecule
• you add extra bases to template strand to make it longer

Question 1

Telomeres

Answer 1

• ends of chromosomes cannot be replicated using normal DNA replication mechanisms because there is a lot of machinery and lagging strand needs it to be in front
• without telomere you’d lose approx. 100 nucleotides off lagging strand
• telomeres are the special repeating DNA structures at the end of linear chromosomes
• in human chromosomes there are about 10,000 nucleotides of the repeating unit, GGGTTA (remember there are a lot of Gs!)

Question 3

G-quartet

Answer 3

• the single-stranded region at the end of the DNA folds back on itself and the G residues form a special structure to form “knots”
• proteins bind to these G-knots and ‘count’ the number of G-knots - they say “if you don’t have enough G’s/telomere sequence, you are getting old, and maybe you should cut back on your activity”