centromeres

Question 1

describe the yeast point centromere

Answer 1

only 120bp
highly conserved sequence in regions I and III
Very AT rich region in the middle

Question 2

What is the function of a centromere?

Answer 2

Specialized chromosomal region for kinetochores to assemble (link centromeres to spindle fibres)

Question 3

Describe the human regional centromere

Answer 3

Contains ALPHOID SATELLITE DNA - AT rich sequences.
Each repeat is 171bp.
organized as tandem arrays at the centromeres of all human chromosomes.

Question 4

What are some key features found at centromeric nucleosomes?

Answer 4

CENPA replaces 2 x H3

H3K4me2

Question 5

How does the kinetochore recognize centromeric DNA

Answer 5

recognizes methylation of centromeres, attaches centromeres to mictrotubules and allows segregation at mitosis

Question 6

Discuss holocentric centromeres in c.elegans

Answer 6

cenH3 histones are distributed throughout the chromosome, attachments to the centromere are all along the chromosome.

Question 7

What type of origin of replications do lower eukaryotic organisms contain?

Answer 7

Autonomous replication sequences.

Question 8

How can you find origins of replication in animals

Answer 8

can isolate newly synthesized DNA by BrdU. this is an analogue of base T can be integrated instead of T at replications
Immunoprecipitate.
Microarray to determine sequence

Question 9

Discuss which various elements you might find at Origin of Replication of metazoan cells

Answer 9

AT rich sequences or CpG islands
Nucleosome packaging
Promoter and Enhancer regions
looped MARs