The Nucleus Flashcards
what is the nucleus
a large, membrane-bound structure usually located near the center of the cell
what can the nucleus be in terms of shape
spherical, elongated, or lobed, depending on the cell type.
what kind of cells loose their nucleus as they develop
RBC
what cells contain more than one nucleus
skeletal muscle cells and certain bone cells, called osteoclasts
the nucleus consists of three main things
nucleoplasm, nuclear envelope, nuclear pores, nucleolus, nucleolar organizer regions
what surrounds the nucleoplasm
the nuclear envelope
what is the nuclear envelope made of
two membranes separated by a space
what are nuclear pores
at many points on the surface of the nuclear envelope the inner and outer membranes of the nuclear envelope fuse they form pore like structures called nuclear pores
through what do molecules move from nucleus to cytoplasm
through nuclear pores
Deoxyribonucleic acid (DNA) is mostly found where
within the nucleus, although small
amounts of DNA are also found within mitochondria
Nuclear DNA and associated proteins are
organized into discrete structures called
chromosomes
the proteins of chromosomes are called
histones
During most of the life cycle of a cell, the chromosomes are dispersed
throughout the nucleus as delicate filaments referred to as
chromatin
what happens to chromatin during cell division
the dispersed chromatin becomes densely coiled,
forming compact chromosomes
At the beginning of cell division, each chromosome consists of
two chromatids attached at a single point called centromere
