Chromosome Structure Flashcards
How is the nucleus useful in separating things
It separates DNA from the cytosol.
Separates transcription from translation.
What does the nucleus organise
Genes into chromosomes to allow cell division.
The uncoiling of DNA to replicate key genes.
What does the nucleus produce
Messenger RNA that codes for proteins.
Ribosomal RNA in the nucleolus
Give an example of a disorder cause by mutation of the lamins in the nuclear lamina
Progeria.
Changes the shape of cell nuclei.
Affects the cells ability to divide correctly.
Results in accelerated aging.
Function of the nuclear lamina
Provides structural support for chromosomes.
Maintains nuclear shape.
Essential in disintegration of nuclear envelope during mitosis.
What are the functions of the nucleoplasm
To act as a suspension medium for the organelles of the nucleus.
To maintain nuclear shape and structure.
To transport ions, molecules and other substances important to cell metabolism and function.
What can and how do they move through a nuclear pore
Small proteins and ions, diffuse through.
Larger proteins, actively transported by transporter molecule.
How do transporter molecules work
They bind to large proteins and interact with nucleoporins as they pass through
What 3 compartments can be identified in the nucleolus
Fibrillar center.
Dense fibrillar component.
Granular component.
What happens in the nucleolus
Protein and DNA complexes are found in the fibrillar centre.
Ribosomal units are made in the dense fibrillar component.
Ribosomes are assembled in the granular component.
What aspect allows histones to bind easily to DNA
They contain lots of positively charged amino acids (arginine and lysine) so bind to negative DNA
When does chromatin begin to condense into chromosomes
After S phase, and is visible during metaphase
What size fibre does a nucleosome fold up to create
30nm
How long are the loops formed from the 30nm fibre
300nm
The 300nm loops are compressed and folded, how long are they now
250nm
