BSCI330 nuclear and chromosomal structure Flashcards
what is turgor pressure
hydrostatic pressure driven by osmotic forces
Water will pass down its concentration gradient from hypotonic to hypertonic solution. Water will try to get in and creates a pressure to equalize concentration gradient, which gets water to stop coming in. The pressure is turgor pressure.
what can turgor pressure determine
the direction of growth
what are eukaryotic cells defined by
the presence of a nucleus, which has a double membrane which communicates with cytoplasm via large nuclear pores
what is DNA in the form of
chromatin, a complex with histones and other proteins
chromatin is dynamic and changes with the needs of the cell
what does the nucleus contain
genetic material of DNA in double membrane structure
what is the double membrane of the nucleus continuous with
the ER
what shape is the nucleus
spherical, given by nuclear lamina, which provides binding sites and internal organization to nucleus
what are subdomains
how the nucleus is compartmentalized. They are not separated by membranes and can assembled/disassembled as needed
what is the most understood subdomain
nucleolus (where ribosomes are synthesized)
what is transport between cytoplasm and nucleus regulated by
large nuclear pores made up of 30 proteins called nuclearporins
how do proteins pass through the large nuclear pores
the smaller the protein, the easier it is to diffuse freely. Larger molecules need active transport
what does chromatin do
condenses linear DNA molecules to fit within nucleus
what is the basic unit of chromatin
nucleosome (150 nucleotides of DNA wound around a core of histone proteins)
how are linker DNA between nucleosomes described as
beads on a string
when cells aren’t dividing, what is chromatin condensed into
30 nm fiber (formed between N-terminal tails of histones in neighboring nucleosomes)
