Cell wall + nucleus Flashcards
How many membranes does the nuclear envelope have?
2
Where are ribosomes found?
Bound ribosomes - in rER, free ribosomes - in the cytoplasm
What is the function of the nucleus
Storage of genetic info and control center
What causes the coiling of nucleosomes, which later is made into chromosomes?
Histone 1
What is the function of the nuclear pore complex?
Controls the movement of molecules out of, or into, the nucleus (nucleo-cytoplasmic exchange).
What is the structure of the nucleus?
The nucleus is surrounded by the nuclear envelope, has channels called nuclear pores, contains tightly packaged DNA, and has a prominent area called the nucleolus.
What is the nuclear envelope composed of?
Two membranes: an outer membrane and an inner membrane, each being a phospholipid bilayer.
What is the role of the nuclear lamina?
Maintains the shape of the nucleus and helps organise the packing of the DNA within the nucleus.
What happens if the nuclear lamina is defective?
Cells cannot produce a typical nuclear lamina, leading to atypical nuclei that cannot maintain a spherical shape, limiting cell division and resulting in premature aging.
What types of RNA move from the nucleus to the cytoplasm?
mRNA, tRNA, and ribosomal subunits.
What types of materials move from the cytoplasm to the nucleus?
Control signals, building materials, and energy.
What is the nucleolus responsible for?
Making ribosomal RNA and ribosomal subunits.
How is DNA organised within the nucleus?
DNA is tightly packaged around histone proteins forming 10-nm fibres and nucleosomes, which are further packaged into larger fibres and, during cell division, into chromosomes.
What is the difference between euchromatin and heterochromatin?
Euchromatin is less tightly packed and contains genes being used by the cell, while heterochromatin is more tightly packed and contains genes not being used.
What coils DNA into beads
Histone 2 and 4
What is the diameter of the nucleus?
5–10 µm.
How many nuclear pores are typically found per cell?
Approximately 1000.
What is the significance of the nucleolus in non-dividing cells?
It is a prominent nuclear structure responsible for making ribosomal RNA and ribosomal subunits.
