cells that have two copies of each chromosome. they are also known as somatic cells
haptoid
cells that have only one copy of each chromosome
ex. egg and sperm
unique sequences
every species contains its own unique sequence of DNA that contains regulatory regions, exons, and introns.
repetitive sequences
highly repetitive DNA: short repeated polynucleotides of 5 to 500 base pairs that comprises 10-15% of DNA and is located in centromeric and telomeric regions. Are transcriptionally inactive.
moderately repetitive DNA: a large variety of repeated sequences found throughout the chromosome, with a majority of the sequence containing spacers (introns). Ex. rRNA precursor gene
chromatin
a compacted DNA protein complex that contains nucleosomes.
histone
a gamily of positively charge proteins where the negatively charge phosphate backbones of DNA winds around to form nucleosomes
nucleosome
a protein DNA complex that contains a histone and non histone proteins where DNA spools around it.
telomere
tips of chromosomes with repeating units of 6 to 8 base long sequences of Ts and Gs
centromere
DNA sequences that are required for segregation of replicated chromosomes to daughter cells
heterochromatin
when dyed, will produce dark bands on the chromatin. Consists of highly repetitive DNA and are transcriptionally inactive. found near centromeres and telomeres
euchromatin
less condensed and light bands on chromatin. are transcriptionally active.