unit 1.3 gene expression Flashcards
what are RNA
single stranded nucleotide
contain ribose sugar and instead of thymine it has URACIL
types of RNA
mRNA: carries a copy of DNA to the ribosome from nucleus
rRNA: rRNA and proteins to form a ribosome
tRNA: carries specific amino acids to the ribosomes
structure of mRNA
transcribes in DNA, translated to proteins form mRNA
each triplet base on mRNA: called a codon and codes for specific amino acids
structure of tRNA
fold due to complementary base pairings
has anticodon and attachment site for specific amino acids at the other end
gene expression
use gene to syntheses protein
has 2 processes
- transcription
- RNA splicing
- translation
process of transcription (DNA-mRNA)
- polymerase moves along unwinding double stranded helix and breaks H bond between bases
- polymerase synthesises primary transcript by complementary base pairings
process of translation (mRNA-protein)
- start on start and end on stop codon
- anticodon bond to codon by complementary base pairings, translate genetic code to sequence of amino acid
- peptide bond Join amino acid to together
tRNA leaves the ribosome as polypeptide form
RNA splicing
form mature transcript
introns (noncoding regions) are removed whilst exons (coding regions are retained and included in the mature transcript
exons are translated
alternative RNA splicing
different protein expressed from 1 gene results in alternative RNA splicing
meaning some interns are retained
different mature transcript are formed from the dame primary transcript depending which exons are retained and which arent
proteins
amino acids are linked by peptide bond form polypeptide (protein)
polypeptide fold for what reasons
polypeptide fold to 3D shapes because of the proteins which are held by H bond and the interactions between individual amino acids
phenotypes
physical characteristics produced by proteins
what can influence the3 phenotype
environmental factors
protein produced from gene expression
