Unit one - Gene expression Flashcards
what does gene expression involve?
involves the transcription and translation of DNA sequences
what do transcription and translation involve?
three types of RNA - mRNA, tRNA and rRNA
what is RNA?
RNA is single-stranded and composed of nucleotides containing ribose sugar, base and phosphate
what are the base pairings in an RNA molecule?
Adenine and uracil, Guanine and cytosine
what is mRNA?
messenger RNA carries a copy of the DNA code from the nucleus to the ribosome
how is this mRNA transcribed?
it is transcribed from DNA in the nucleus and translated into proteins by the ribosome in the cytoplasm
whats is tRNA?
transfer RNA folds due to complementary base pairing, each tRNA molecule carries its specific amino acid to the ribosome
what is an anticodon?
an exposed triplet of bases
what is rRNA?
ribosomal RNA and proteins form the ribosome
what is the role of RNA polymerase in transcription into primary mRNA transcripts?
RNA polymerase moves along the DNA unwinding the double helix and breaking the hydrogen bonds between the bases
what does RNA polymerase synthesise?
it synthesises a primary transcript of mRNA and RNA nucleotides by complementary base pairing
what does RNA splicing form?
forms a mature mRNA transcript
what are introns?
non-coding regions which are removed
what are exons?
coding regions which are joined together to form the mature transcript, order of these exons are unchanged
what is tRNA?
involved in the translation of mRNA into a polypeptide at a ribosome
what is translation?
it begins at a start codon and ends at a stop codon
what do anticodons do?
they bond to the codons by complementary base pairing, translating the genetic code into a sequence of amino acids.
what joins amino acids together?
Peptide bonds to form polypeptides
what is the result of alternative RNA splicing?
different proteins can be expressed from one gene, different mature mRNA transcripts are produced at the same primary transcript depending on which exons are removed.
what do polypeptide chains do?
they fold to form the three-dimensional shape of a protein
what is a phenotype?
it is determined by the proteins produced as a result of gene expression, environmental factors affect this.
