nucleus Flashcards
who first described the nucleus as an organelle?
Robert Brown(1831)
who discovered chromatin and name the dye used to do so?
Flemming used basic dye to stain nuclear material and named it chromatin.(1879)
name a binucleate organism?
paramecium.
name a multinucleate organism?
Opalina
name an anucleate cell?
mammalian RBCs and mature sieve tube cells
what is a nucleus?
the nucleus is a comparatively large organelle responsible for controlling all activities in a eukaryotic cell.
explain the structure of the nucleus?
nucleus at the non-dividing phase is called interphase, during interphase nucleus is differentiated into nucleoplasm or nuclear matrix, nuclear envelop, chromatin, nucleolus.
what is a nuclear envelope?
it is responsible for separating the nucleus from the cytoplasm. it is made up of to membrane, the inner membrane is smooth while the outer membrane may be smooth or may have ribosomes like RER.the outer membrane is often connected to the ER the inner and outer membrane is separated by perinuclear space. nuclear pores are formed by the fusion of two membranes, bidirectional transport occurs through these pores and they control the entry and exit of materials like DNA, ribosomes and protein.
what is the width of the perinuclear space?
10 nm - 50 nm
what is nucleoplasm?
it is a transparent semi fluid and colloidal substance which fill the nucleus. it contains nucleolus and highly extended and elaborated nucleoprotein fibers called chromatin.
what is nucleolus?
it is a speherical structure , not bounded by a membrane present in the nucleus.it is the site for RNA(rRNA) synthesis. thus the nucleoli is larger and more numerous in cells that are actively involved in protein synthesis.
what does Chroma mean?
color
