DNA transcription and translation- protein syn Flashcards
(14 cards)
whats a triplet code
each amino acid coded for by 3 bases. some amino acids coded for by more than one triplet code so is degenerate. some bases act as stop codons.
non overlapping so each base is only part of one triplet
universal same amino acid in every organism
introns non coding
exons coding
whats a gene
section of dna that codes for the amino acid sequence of a polypeptide and functional rna
whats a locus
the fixed position on a dna molecule that a gene occupies
whats a genome
complete set of genes in a cell including
whats a proteome
complete set of proteins that a cell can produce
describe transcription
its the production of mRNA from DNA
DNA helicase breaks the h bond between bases and causes the DNA strand to unwind. 1 strand acts as a template
RNA nucleotides attracted to exposed bases and bind with complementary pairs
RNA polymerase moves along the template strand causing RNA nucleotides to join together.
DNA rewinds behind as the RNA detaches
RNA polymerase will stop when it reaches a stop codon
pre mrna is formed
how change from pre mRNA to mRNA
introns removed to leave only exons through the process of splicing. only happens in eukaryotes
describe translation
production of polypeptides
ribosome attaches to mRNA at starting codon
tRNA molecule arrives and its complementary anticodon binds to mRNA codon meanwhile it brings an amino acid
another tRNA molecule does the same. ribosome moves along the mRNA. the amino acids are joined by peptide bonds.
energy from the hydrolysis of ATP used to do this. ribosome moves to 3rd codon and first tRNA is released
whats the difference between mRNA and tRNA
mRNA longer has more nucleotides than tRNA
mRNA straight molecule tRNA clover leaf shape
mRNA contains no paired bases but tRNA has some paired bases
whats a mutation
changes in sequence of bases in the DNA. change order of amino acids and thus the H/ionic/disulphide bonding and change the tertiary structures of a polypeptide
how can mutations make non functional protein
amino acid sequence changed
change in h and ionic bonds
tertiary structure is altered and thus the
no enzyme substrate complexes formed
what are the two types of mutation
deletion substitution
describe substitution
a base is substituted for another. can lead to a different amino acid being coded for, same amino acid being coded for (degenerate) or a stop codon being coded for
describe deletion
a base is deleted causes frameshift
