Two main fxn's DNA serves
it passes information it encodes to the next generation, so that progeny cells and offspring look and behave much like their parent cells
DNA also provides the blueprints or recipes for maintaining cellular fxns
phosphodiester bond
resulting covalent bond of nucleotide bonds
DNA double helix
made of two polynucleotides (two long strands of nucleotides wound around each other)
base pairing
adenine only hydrogen bonds w thymine
cytosine " " w guanine
DNA in nucleus
nearly all the cells DNA is packaged and sequestered by the nucleus
mitochondria (DNA)
there is a minor amount of DNA within it as well
genome
the complete set of DNA within in a cell
chromosome
humans possess 46 pieces of unique DNA each called a chromosome. each has a matching partner allowing humans 23 pairs of chromosomes, so we have two copies of our genome inside the nucleus of every one of our cells
single chromosome
a very long double helix strand of DNA so long that it cannot fit inside the nucleus of a cell without being tightly packed
if all the human DNA from one cell was stretched out it be 6 feet 2 meters long
nucleus length
approx. 6 microns in diameter which is 70,000 times smaller than the avg chromosome.
packaging DNA into chromosomes
the cell uses proteins to twist the DNA into incredibly tight bundles
genes
sequences of DNA that encode something that the cell can use.
usually genes encode for proteins
but some encode for functional RNA molecules like tRNA and rRNA (transfer and ribosomal)
"genes are the sentences in a chromosome
regulatory binding sites
proteins on genes that control if and when a gene gets decoded
junk DNA
non gene DNA we do not know the purpose of yet.. long strands of DNA can separate genes
codons
triplets of nucleotide bases that encode for an amino acid
genetic code
sequence of amino acids that make a protein
making RNA
to make an RNA copy from a DNA gene, the two hydrogen-bonded strands from the double helix unwind near the beginning of the gene. Proteins then use the unwound strands of DNA as a
template
and build a
complementary strand
of RNA
tRNA
happens at the site of the ribosome and helps transfer mRNA into amino acid codons (64 possible codons)
synthesis phase of the cell cycle
where replication of DNA occurs
chromatid
duplicate chromosome, each pair of each chromosome duplicates are called "sister chromatids