Lecture 4

Question 1

what is the structure of chromosomes

Answer 1

highly coiled fibre of chromatin wrapped around histone proteins

Question 2

structure of histones

Answer 2

8 subunits
highly charged
can move back and forth to open up sites of DNA for replication

Question 3

what are linker histones

Answer 3

H1
strap DNA onto histone octamers
stabilises and facilotates establishment of silent DNA

Question 4

what are telomeres

Answer 4

specialised ends of chromosomes that maintain integrity
replicates by telomerase
TTAGGG

Question 5

what are centromeres

Answer 5

where kinetochores assemble
contain alpha-satelite DNA repeats
bind to inner plate kinetochore proteins
outer plate kinetochores bind to spindle
contains specialised histone CENP-A taht mediates attatchemnt of chromosome to kinetochore
and H3-K4ME that helps to hold sister chromatids together

Question 6

the more complex the organism the more

Answer 6

protein encoding parts

non protein encoding DNA

Question 7

what are the three different transposons

Answer 7

DNA transposon
retroviral retrotransposons
non-retroviral poly A transposons
mobile genetic elements that jump around genome