DNA Replication and Chromosomes: DNA and Chromosomes Flashcards
(43 cards)
How is DNA packaging within chromosomes characterised?
Not constant.
How are more active DNA regions packed?
Less lightly.
How are less lightly DNA packed regions shown?
As bands on the chromosome.
How is Heterochromatin packed?
Tightly packed.
In how many forms does heterochromatin come?
In 2 forms.
Which are the 2 forms of heterochromatin?
- Constitutive.
2. Facultative.
What is the constitutive heterochromatin?
A permanent structure.
What does the constitutive heterochromatin contain?
No active genes: centromeres, Y chromosome.
What is the facultative heterochromatin?
A temporary structure.
What does the facultative heterochromatin contain?
Genes which are switched off sometimes: regions for embryo development switched off after completed development.
How is euchromatin packed?
Loosely packed.
What does eychromatin contain?
Actively-expressed DNA.
How can the chromosome structures be described?
Length of the arms relative to central bodyz.
Which is the central body in the chromosome structure?
The centromere.
What does the centromere link during replication?
A pair of sister chromatids.
Where do protein spindles connect?
To the centromere.
How are the protein spindles connected to the centromere?
Via the kinetochore.
Why do protein spindles connect to the centromere?
To move chromosomes within the nucleus.
What do telomeres define?
The end of the chromosome arms.
What do the telomeres help determine?
Age.
What happens to each chromosome during DNA replication?
It is duplicated.
Why is each chromosome duplicated during DNA replication?
To form the classic ‘X’ chromosome structure.
What does an individual have?
A copy of chromosomes from each parent.
How does a copy of chromosomes from each parent called?
‘Chromosome pairs’.
