national 5 biology key area one; DNA and the genome

describe the structure of DNA

DNA is a double helix, which consists of 2 long chains of subunits called nucleotides.

describe the components of a nucleotide

• deoxyribose sugar

• phosphate group

• nitrogenous base

name the four nitrogenous bases

The four nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine. These bases pair specifically: adenine with thymine, and cytosine with guanine.

what is the backbone known as, and what is it composed of

the backbone of DNA is known as the sugar-phosphate backbone and is composed of sugar phosphate groups and deoxyribose

name the type of bond between complementary base pairs

weak hydrogen bonds

what kind of structure does DNA run under

the anti-parallel structure

what forms the genetic code

the sequence of bases in DNA forms the genetic code

describe the dna in a prokaryotic cell

prokaryotic cells have a single circular chromosome, they also have additional small circular sections of DNA called plasmids.

describe DNA in a eukaryotic cell

eukaryotic cells have linear DNA contained in a true nucleus with associated proteins, small circles of DNA are present in chloroplasts and mitochondria

how are proteins contained in a eukaryotic cell

the dna double helix is wrapped around histone proteins

describe why yeast is a special example of a eukaryote

as yeast cells also contain plasmids