the Nucleus Flashcards
describe the nucleus
- the most important organelle (5-10 micrometers)
- one nucleus per cell
- contains most of the cells genes
- perinucleus space
- the nucleus envelope is continuous to the ER
- the perinucleus space is continuous to the lumen ER
- serves as repository inherited genetic information
- has 2 membranes
describe the nucleus pore complex
- Controls the movement of molecules out of or into the nucleus
what goes out of the nucleus pore complex
- mRNA: messenger RNA - carries information from a gene
- tRNA: transfer RNA , and Ribosomes are needed to build proteins
what goes into the nucleus pore complex
- control signals: to tell when to turn a gene on or off
- building blocks: to build RNA
- energy: for chemical synthesis
within the nucleus, what is the inner surface of the nuclear envelope lined with
- nuclear lamina
what is the nuclear lamina composed of
- intermediate filaments
what does the nuclear lamina do
- helps maintain shape of nucleus
- helps to organize the packing f the DNA within the nucleus
what is the Nucleolus
- a prominent nuclear structure within non-dividing cells
- may be 2 or more nucleoli per cell depending on species and stage of cell cycle
what is the nucleolus responsible for
- for making ribosomal RNA which then combines with proteins to produce ribosomes
how big is the DNA double helix
2nm in diameter
what does the helix interacts with
- histones (H2-H4)
what does the interaction between the helix and histones form
it forms a 10nm diameter fiber called nucleosome
another interaction occurs between DNA and another Histone (H1), what does this do
- causes the 10nm coil to form a 30nm fiber
what does the 30nm fiber then do
loops to form a 300nm fiber
during cell division what does the 300nm fiber coil form
metaphase chromosomes
