BIOU2CE THE NUCLEUS

Genome role

contains all of the information an organism needs for all cell types

genone made of

dna

how dna is expressed in the genome

through translation and transcription

how the genome is used

used differentially to give rise to phenotypic variation

structure of chromosomes

linear with specialised features

centromeres

structures at which chromatids are joined during mitosis and are pulled apart

telomeres

specialised chromosome ends that prevent degradation of the chromosome

centromere structure

highly condensed DNA, where proteins connect to DNA and mitotic spindle fibres

telomere formation

made each round of chromosomal replication

shorten each time, associated with cell decay

nucleus role

specifies activity in the cell

DNA to protein pipeline

DNA transcribes to make RNA

mRNA codes for proteins

ribsomes attach to mRNA

ribosomes translate mRNA to make proteins

Where DNA is stored

Most in Nucleus

some in mitochondria (animals) and chloroplasts (plants)

how nucleus is separated from the cytoplasm

nuclear envelope

what nuclear envelope allows

selective movement of material in and out of nucleus

nuclear envelope structure

double membrane

what passes into the nucleus

proteins required for DNA synthesis and transcription

What leaves the nucleus

RNA leaving for translation

membranes of the nuclear envelope

lipid bilayer with associated proteins separated from each other by 20-40nm

proteins that are studded throughout the whole nucleus

nuclear pores

protein lattice lined inside the nuclear envelope

nuclear lamina

role of the nuclear lamina

supports the nucleus and gives it its shape

provides points at which the nuclear matrix attaches to organise DNA in the nucleus

why nuclear envelope dissapears transiently during cell division

a reversible disassembly of the nuclear lamina at the correct phase in the life of the cell

how many nuclear pores will a nucleus have

~3000 nuclear pores

size of nuclear pores and their role

diameter of ~100 nm and allows 2-way passage of material across the nuclear envelope

outside structure of nuclear pores

projections called cytoplasmic filaments

inside structure of nuclear pores

nuclear basket made of over 100 different proteins

motif to enter nucleus

Nuclear Localisation SIgnal

Motif to leave the nucleus

Nuclear Exit Signal

what proteins bind to to enter nucleus

importins

what separates proteins from importins

RanGTP

how RanGTP and importins leave the nucleus

exportins

makes up the protein lamina

group of proteins called lamins

Makes up chromosomes

Chromatin (DNA and Specific proteins)

details of individual chromosomes

Only seen in dividing cells

how chromosomes in non-dividing cells are kept

separated, forming chromosome territories

euchromatin and its role

decondensed DNA, relatively ‘open’ and can be accessed read for transcription

Heterochromatin and its role

condensed DNA, less accessible and not easily transcribed

nucleolus

found in non-dividing cells, fibrous, densely stained mass

nucleolus role

site where ribosomal RNA is synthesised

formation of ribosomal subunits

imported proteins combine with rRNA

structure of ribosomes

made of large and small subunits