U1 - Structure and Organisation of DNA Flashcards
describe the stucture of DNA
DNA is a double helix with antiparallel strands
describe the role of covalent bonds in DNA strands
nucleotides are joined together by covalent bonds, from the phosphate of one nucleotide to the deoxyribose of the next. This forms the sugar-phosphate backbone
what is meant by the term prokaryote
an organism which lacks a true membrane-bound nucleus i.e. bacteria
what is meant by the term eukaryote
an organism which has a true membrane-bound nucleus i.e plants, animals, fungus
state the features of prokaryotic cells
DNA is held in the cytoplasm in a singular circular chromosome and circular plasmids; lack a true membrane-bound nucleus
state the features of eukaryotic cells
DNA is held in the NUCLEUS, tightly coiled around proteins called histones into linear chromosomes; mitochondria and chloroplasts also contain circular chromosomes; eukaryotic cells have a true membrane-bound nucleus
where is DNA found in eukaryotic cells other than the nucleus?
circular chromosomes can be found in the mitochondria and chloroplasts of plant + animal cells
what is a plasmid?
a circular, self replicating DNA molecule which carries only a few genes
what makes the structure of a yeast cell interesting?
yeast is a eukaryote but has plasmids like prokaryotes do
