Eukaryotic Chromosome Structure and Function Flashcards
Which dye binds to chromosomes?
DAPI
When are chromosomes visible?
During cell division
Proteins contained in the nucleus are involved in what?
Packaging and unfolding of DNA within the nuclues
Controlling DNA replication, DNA repair and genetic recombination
Maintainging chromosome integrity by preventing loss of end sequences
Governing segregation
Regulating gene expression
Which organelles contain some DNA?
Mitochondria and chloroplasts
What is a karyotype?
The organised representation of all the chromosomes in a eukaryotic cell at metaphase
The chromosomes are painted a different colour each
Where is transcriptionally inactive DNA located in the interphase nuclues?
On the periphery
Trasncriptional activation of a gene is accomponied by what movement?
The genes move from the periphary to the centre of the nuclues
They move out of their chromosome territory to centre of the nucleus
How thick is condensed isolated chromatin?
30nm thick
What are the protein subunits of the nueclosomes called?
Core histones
How many subunits make up a core histone?
8
How do histones regulate chromatin structure and function?
They have 8 tails which can interact with other other proteins
What is a telomere?
DNA sequences at the ends of linear chromosomes that maintain chromosomal integrity
What is a replication origin?
DNA sequences where DNA replication is initiated
What is a centromere?
DNA sequences on which kinetochores assemble and mediate chromosome segregation at mitosis and meiosis
What is a kinetochore?
Protein complex that binds microtubules in the mitotic spindle
What is the sequence of a telomere?
Repeats of TTAGGG
Which enzyme replicates telomeres?
Telomerase
Where are alpha satellite sequences located?
In condensed heterochromatin
What do kinetochore inner plates bind to?
Alpha satellite DNA
What do kinetochore outer plates bind to?
Components of the mitotic spindle in microtubules
Describe the kinetochore in yeast
Basket that links a single nucleosome of centromic chromatin to a single microtubule
How many microtubules can human kinetochores capture?
20
How much of the human genome codes for the proteins?
1.5%
50% of what makes up the human genome?
repeated DNA sequence elements
Retrotransposons are also known as what?
Parasitic DNA
What is the role of transcriptional regulatory information?
Determines where and when in the body adjacent coding genes are expressed
Increasing biological complexity depends on what?
1) Increasing numbers of protein coding
2) Increasing amounts of non protein coding cis-regulatory DNA for regulating and organising access to protein coding genes
What are the three types of transposons?
DNA transposons
Retroviral transposons
Non-retroviral polyA retrotransposons
What are transposons?
Mobile genetic elements that jump around the genome
How can transposons move?
Move by cut and paste mechanisms without self duplication requiring the transposon encoded enzyme transposase
List three examples of transposons
P element in drosophila
Ac - Ds (maize)
TN3 / TN10 (E.coli)
Who discovered transposons (Ac-Ds) of maize?
Barbara McClintock in 1952
List three examples of retroviral retrotransposons
Ty1-copia
Ty3-gypsy
EAV elements
Where are PolyA retrotransposons found?
Abundant in vertebrate genomes
How do PolyA retrotransposons replicate?
Via an intermediate using its own retrotransposon encoded reverse transcriptase ie by copy an paste
List three examples of PolyA retrotransposons
Human Ll elements
Human Alu elements
Mouse B1 elements
Give an example of a disease which is caused by a gene due to Ll insertion
Haemophilia
