U2 LEC: NUCLEIC ACID STRUCTURE Flashcards
Two essential components of nucleus
Nuclear Membrane and Nuclear Pores
The nuclear membrane is studded by?
free ribosomes
Importance of free ribosomes in the nucleus
protein translation of MRNA
The inner membrane consists of a protein called?
Lamin
This protein is responsible for interaction with chromatin, and allows gene expression.
Lamin
This is a mutation in which an individual ages very rapidly.
Progeria
What goes out of nuclear pore?
messenger RNA
Messenger RNA cannot go back to the nucleus because it is already?
polyadenylated and cut
What comes in of the nuclear pore?
nucleotides (deoxyribonucleotides), transcription factors
Nucleolus contains?
- ribosomal rNA
- protein subunits
T/F: Nucleolus is not true for all cells, but true for mammalian cells.
True
What happens in the nucleolus?
ribosome formation
Densely packed chromatin
Heterochromatin
Loosely packed chromatin
Euchromatin
This chromatin is easier to translate because it is easily accessible by transcription factors.
Euchromatin
This is a protein which helps pack the DNA.
Histones
Charge and residues of Histones
positive charge, Lysine and Arginine
Characteristic appearance of Histones
bead-like structure
This is formed once DNA loops with histones.
Nucleosomes
Histone consists of how many subunits?
8 (octamer)
Subunits of the histone protein
H2A, H2B, H3, H4 (2 each)
Linker protein in histone which modifies the distance between nucleosomes, and alters compaction
H1
This refers to DNA looped with histones.
Nucleosome
T/F: If DNA is looped, it can still be accessible by transcription factors.
False
Only accessed once histone protein is modified (uncoil)