chromosomes

Question 1

at what stage of mitosis can individual chromosomes be most easily seen?

Answer 1

metaphase

Question 2

DEFINE: karyotype

Answer 2

the organised representation of all the chromosomes in a eukaryotic cell at metaphase

Question 3

define the structure of nucleosomes

Answer 3

8 core histone subunits
30 aa long n-terminal tails of core histones projecting from nucleosome core
n-terminal tails interact with other proteins to help regulate chromatin structure and function

Question 4

DEFINE: replication origin

Answer 4

DNA sequence where DNA replication is initiated

Question 5

describe the structure of the centromere

Answer 5

• alpha satellite dna repeats with h3k4me and cenp-a histones
• cenp-a –> contains centromere-specific histone h3 variant - attaches chromosome to kinetochore
• h3k4me –> methylated core histones —> holds sister chromatids together
• kinetochore outer plate - bound to alpha satellite dna repeats
• kinetochore inner plate - bound to microtubules

Question 6

what are some examples of transposons?

Answer 6

p element in fly
tn3/tn10 in e coli
activator dissociator in maize

Question 7

what are some examples of retroviral retrotransposons?

Answer 7

ty1-copia
ty-3 gypsy
ERV elements

Question 8

what are some examples of non-retroviral polyA retrotransposons

Answer 8

humans
- LINE1 elements 
- Alu elements (SINEs) 
mice
- B1 elements (SINEs)

Question 9

DEFINE: transposons

Answer 9

DNA sequences that can move around the genome