protein synthesis and DNA 3.4.2 Flashcards
define gene
section of DNA on a chromosome coding for one or more polypeptides
define allele
one of a number of alternative forms of a gene
define locus
position of a gene on a chromosome/DNA molecule
what are the stop codons
UAA UAG UGA
what does the stop codon do
tells RNA polymerase to detach itself
what is the start codon
AUG
what does the start codon do
initiates action of RNA polymerase
what is an exon
coding sequence that is expressed
what is an intron
non coding sequence that’s not expressed
what is splicing
when introns are removed from pre mRNA to form mRNA
define genome
the complete set of genes or genetic material present in a cell or organism
define proteome
the full range of proteins that a cell is able to produce
what does mRNA do
brings information from DNA in nucleus to ribosomes in cytoplasm, directs synthesis of polypeptides
what does tRNA do
transports amino acids to ribosomes, positions each amino acid at correct place on polypeptide chain
transcription
- hydrogen bonds break (DNA helicase)
- one DNA strand acts as template
- free RNA nucleotides align by complementary base pairing
- uracil pairs with adenine
- RNA polymerase joins nucleotides by phosphodiester bonds
- pre mRNA is spliced to form mRNA
- leaves nucleus via nuclear pore
translation
- mRNA attaches to ribosomes (on rough ER)
- tRNA anticodons bind to complimentary codons
- tRNA brings a specific amino acid
- amino acids join by peptide bonds with the use of ATP (and ribosomal enzyme)
- tRNA released
- ribosome moves along the mRNA to form the polypeptide
define universal genetic code
same codon always codes for the same amino acid
define non-overlapping code
each base is only part of one codon
define degenerate code
multiple codons code for one amino acid
