26. Nucleus Steucture Flashcards
Nucleus structure
Do they exist in all eukaryotic cells? How many nucleus are there usually in one cell? What does uninuclear mean? What does binuclear mean? What is a multinuclear cell mean?
How many chromosomes does it have? Haploid? Diploid?
Localisation of nucleus? Where is it sometimes moved?
It does exist in all eukaryotic cells except erythrocytes and some dead cells. There’s usually 1 nucleus per cell. Uninuclear means it’s one nuclei. Binuclear means it has two nuclei. Multinuclear means it has multiple nuclei.
The number of chromosomes depends. There’s haploid number which is half the normal number of chromosomes. Sex cells have haploid number of chromosomes. Diploid is the normal number of chromosomes. Diploid has 46 number of chromosomes.
It’s localisation is in most cases in the centrepiece of the cell. It sometimes moves peripherally closer to the cell membrane.
External morphology nucleus
What’s the shape of a nucleus? How much of the cells volume is it? Whats the size in male sex cells? What size is it in female sex cells? What’s it’s 4 structural components?
Nuclear envelope
Does it have a membrane? What’s the space between its membranes?
Outer nuclear membrane
What is it characterised by? What is present and attached to it? What does the outer membrane have a close connection to?
Inner nuclear membrane
Does it have attached ribosome? What’s it’s outer surface called? What are lamins? What do the layers of lamin form?
What’s the difference between the inner and outer membrane?
The shape of the nucleus is species diversified meaning the shape depends of the cells function that it is in. It is usually egg, oval or kidney shaped. It is 10% or a cells volume usually. In male sex cells it’s about 5 micrometers and in female sex cells it’s about 40 micrometers. It’s 4 structural components are nuclear envelope, chromatin, nucleolus and nucleoplasm which is its nuclear matrix.
The outer nuclear membrane is characterised by intermediate vimentin filaments attached to it. There is presence of attached ribosomes on its surface. The outer membrane has a close connection to the cisternae of the rough endoplasmic reticulum.
The inner membrane is smooth and has no attached ribosomes. It has a nuclear lamina on its surface that is thick. Lamins are layers of specific proteins A,B and C. The collectively form chromatin.
The difference between the inner and outer membrane is it’s structural composition.
Nuclear pore complex
What’s the total number of nuclear pores? What is it composed of? What is it arranged to make? What’s is found in the arrangement of the nuclear pore? What does it allow? How is the ring closed? What are som types of exchanges made between the nucleus and cytoplasm?
The number of nuclear pores varies but it’s usually between 3000 to 5000 nuclear pores. It is composed of about 100 unique proteins called nucleoporins. It is arranged to make 3 rings surrounding a central opening. A diaphragm is found there. The central opening allows communication between the nucleus and the cytoplasm. The ring is closed with a central granule within a pore. Some types of exchanges between the nucleus and the cytoplasm are RNA, proteins, ion and small water soluble molecules.
