Lecture 9 Flashcards
What are the characteristics of the Nucleus
Most prominent organelle (5-10 microns) usually one per cell contains most of the cells genes holds inherited genetic information the control centre of the cell
What is the Nuclear Envelope
Surrounds the nucleus
made of two membranes (phospholipid bilayers)
protects the nucleus
What is the function of the Nuclear Pore Complex
to control movement in and out of the nucleus
What leaves the nucleus through the nuclear pore complex
mRNA-information from gene-code to build protein
tRNA- ribosomal subunits- needed to build proteins
What goes into the nucleus through the nuclear pore complex
Control signals-when to turn a gene on or off
Building materials/blocks- for RNA
energy for chemical synthesis
what lines the inner surface of the nuclear envelope
nuclear lamina
What is nuclear lamina
composed of intermediate filaments
maintain the shape of the nucleus
help organize the packing of DNA within the nucleus
What is a Nucleolus
prominent nuclear structure within non-dividing cells
cell may have 2 or more depending on species and cell cycle
What is the function of the nucleolus
it is responsible for making ribosomal RNA which combines with proteins to produce ribosomes
How much DNA is in the nucleus
approximately 2.5 m that must be packed and accessible as it is 250,000 times bigger than cell
How does the DNA double helix coil
is 2nm
interacts with histone protein to form 10nm fibre,
10nm fibre coils to form 30nm fibre
30nm loops to form 300nm fibre
What happens to the 300nm fibre coil during cell division
they coil to form metaphase chromosomes that can be displayed as a karyotype
What is a karyotype used for
used to screen for chromosomal defects
What is Euchromatin
less dense, contains genes used by that cell
What is heterochromatin
more dense, contains genes not being used by that cell
