Nucleolus

Question 1

what’s the difference between this and a nucleus

Answer 1

Nucleolus makes ribosomes in nucleus. Its not surrounded by a membrane either

Question 2

What are nuclear organising regions

Answer 2

NOR - part of chromosome that contains multiple copies of rRNA genes. 5 pairs of chromosomes hv this.

Question 3

what does the nucleolus contain

Answer 3

DNA, rRNA, enzymes, ribosomal proteins + subunits

Question 4

structure of chromosome.

Answer 4

telomeres
secondary constriction
centromere (primary constriction) - divides chromosome into 2 arms
kinetochore - for attachment of spindle fibres

Question 5

what are telomeres

Answer 5

(ends) - has repetitive nucleotide sequence + protects end of chromosome from chemical injury / fusion with other chromosomes

Question 6

Heterochromatin + eurochromatin

Answer 6

E = most active portion of genome
H = inactive sequence

Question 7

what are the 2 types of heterochromatin

Answer 7

consecutive = poorly expressed centromere + telomere seq

facultative = Not consistent between cell types in species (morphogenesis/differentiation, eg x chromosome inactivation