DNA, genes and chromosomes (8) Flashcards
What is the structure of DNA?
double-stranded
H-bonds between the bases form helix shape
What is the role of DNA?
carries genetic information
determines our inherited characteristics
What is the structure of RNA?
single-stranded
What is the role or RNA?
transfers genetic information from DNA
has ribosomes for protein synthesis
What are the 2 types of bases?
purine
pyrimidine
What is the structure of purine?
double ring
What is the structure of pyrimidine?
single ring
What bases are purine?
adenine
guanine
What bases are pyrimidine?
cytosine
thymine
uracil
Describe the DNA in eukaryotic cells
in nucleus
long + linear
associated with histone proteins to form chromosomes
Describe the DNA in prokaryotic cells
short + circular
not associated with proteins
mitochondria + chloroplasts contain this type of DNA
What is the genetic code?
order of bases on DNA
consists of codons
What are codons?
triplets of bases that code for a particular amino acid
What are 3 features of the genetic code?
non-overlapping
degenerate
universal
What does non-overlapping mean?
each triplet is only read once
What is meant by degenerate?
more than one triplet codes for the same amino acids
How many possible triplet codes are there for how many amino acids?
64 possible triplets for the 20 amino acids
What is meant by universal?
same bases and sequences used by all species
What is a gene?
sequence of bases on DNA molecule that codes for a specific sequence of amino acids to make a polypeptide (can also code for functional RNA)
What is meant by locus?
fixed position on DNA molecule occupied by a gene
What is an allele?
different variations of the same gene, found at the same locus on a chromosome
What are exons?
regions of DNA that code for amino acid sequences, separated by one or more introns
What are introns?
regions of DNA that do not code for anything
found between exons and within genes
