DNA, genes and chromosomes Flashcards
what are the DNA molecules in a prokaryotic cell like?
- short, circular and not associated with proteins
what are the DNA molecules in the nucleus of a eukaryotic cell like?
- very long, linear and associated with proteins called histones
how are chromosomes formed(eukaryotic cells)?
DNA molecule and its associated proteins
what organelles in eukaryotic cells also contain DNA?
- mitochondria
- chloroplasts
what is the DNA like in mitochondria and chloroplasts?
- short, circular and not associated with proteins
what is a gene?
a base sequence of DNA
what do genes code for?
- amino acid sequence of polypeptides
- functional RNA(including ribosomal RNA and tRNA)
where are genes?
they occupy a fixed position, called a locus, on a particular DNA molecule
what is a triplet?
sequence of 3 DNA bases which codes for a specific amino acid
what can the genetic code be?
- universal
- non-overlapping
- degenerate
what is a universal genetic code?
each triplet codes for the same amino acid in every organism
what is degenerate genetic code?
more than one triplet codes for the same amino acids
what is a non-overlapping genetic code?
each triplet is only read once and triplets don’t share bases
what are exons?
base sequence which codes for amino acid sequences
what is non-coding DNA?
DNA that does not code for a sequence of amino acid, positioned between genes
