dna, genes and chromosomes Flashcards
what are the three components of nucleotides
a pentose sugar, phosphate group , an organic base
describe the structure of DNA
made up of a deoxyribose sugar, a phosphate group and one of four organic bases (A, C, G, T)
it is double stranded, and hydrogen bonds between the bases form a helix shape
describe the role of DNA
carries genetic information, determines our inherited characteristics
describe the structure of RNA
made up of a ribose sugar, a phosphate group, and one of four organic bases (A, C, G, U)
it is single stranded
describe the role of RNA
transfers the genetic information from DNA to ribosomes for protein synthesis
which bases are purine
purine are double ring
the bases which are purine are adenine and guanine
which bases are pyrimidine
single ring
bases are pyrimidine are thymine and uracil
DNA in eukaryotic cells
- found in nucleus
- long and linear
- associated with histone proteins to form chromosomes
- mitochondria and chloroplasts contain prokaryotic-like DNA
DNA in prokaryotic cells
- short and circular
- not associated with proteins
what is genetic code
order of bases on DNA
consists of codons (triplets of bases that code for a particular amino acid)
identify features of genetic code
- non overlapping (each triplet read ONCE)
- degenerate (64 possible triplets for 20 amino acids)
- universal (same bases and sequences used by all species)
what is a gene
sequence of bases on a DNA molecules that codes for a specific sequence of amino acids to make a polypeptide. can also code for functional RNA
what is a locus
fixed position on a DNA molecule occupied by a gene
what is an allele
different versions of the same gene, found at the same locus on a chromosome
what are exons
regions of DNA that code for amino acid sequences
