DNA and protein synthesis Flashcards
define gene
a gene is a section of DNA where the base sequence determines the order of amino acids in a polypeptide and functional RNA
define allele
different forms of the same gene
define locus
the position where a gene is found on the chromosome
state how DNA is stored in a eukaryotic cell nucleus?
as chromosomes
define diploid and haploid chromosomes
diploid = full set (23 pairs)
haploid = half set (gametes)
define homologous pairs of chromosomes
2 chromosomes which contain the same genes but may have different alleles
define genome
all the genes in the nuclei (or mitochondria or chloroplasts) of an organism
define proteome
the entire set of protein that is expressed by genome
describe how DNA is stored in a eukaryote
(stored as chromosomes inside of the nucleus which are linear in shape)
1- DNA is tightly coiled around histone proteins which forms nucleosomes
2- nucleosomes further coil to create a chromatin fibre
3- further condensing of chromatin forms chromosomes
how is DNA stored in a prokaryotic cell
DNA is carried in chromosomes BUT the DNA molecules are short, circular and not associated with proteins. Instead it supercoils to fit in the cell.
how is DNA stored in chloroplasts and mitochondria?
DNA which is short, circular and not associated with proteins
What are the three features of the genetic code?
degenerate
universal
non-overlapping
what is the start codon?
the first codon on the DNA and mRNA which initiates translation
what is the stop codon?
the final codon on the DNA and mRNA which causes the ribosome to detach in translation and the process stops (synthesis is complete)
define degenerate
more than one codon codes for each amino acid
how is the degenerate nature proved?
possible codons are 4^3 which is 64 codons that code for 20 amino acids
define universal
the same triplet of bases (codons) codes for the same amino acid in all organisms
(advantageous for genetic engineering)
define non-overlapping
each base is only read or used once
(advantageous for point mutations as only one codon so one amino acid is affected)
