Gene Expression Flashcards
What types of RNA are involved in transcription and translation?
mRNA, tRNA and rRNA
Describe RNA
RNA is single-stranded and is composed of nucleotides containing ribose sugar, phosphate and one of four bases: cytosine, guanine, adenine and uracil.
what does mRNA do
Messenger RNA carries a copy of the DNA code from the nucleus to the ribosome. It is then transcribed from the DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm.
What is a triplet of bases on the mRNA molecule?
They are codons are they code for a specific amino acid
What is tRNA?
Transfer RNA folds due to complementary base pairing. Each tRNA molecule carries it’s specific amino acid to the ribosome. A tRNA molecule has an anticodon (an exposed triplet of bases) at one end and an attachment site for a specific amino acid at the other end.
What does RNA polymerase do in the transcription of DNA into primary mRNA transcripts?
It moves along the DNA unwinding the double helix and breaking the hydrogen bonds between bases. It then synthesised a primary transcript of mRNA from RNA nucleotides by complementary base pairing.
What does RNA splicing form?
A mature mRNA transcript.
What are introns and exons?
Introns of a primary transcript are non-coding regions removed in RNA splicing. The exons are coding regions and joined together to form the mature transcript. The orders of the exons are unchanged during splicing.
Where does Translation begin and end?
It begins at a start codon and ends at a stop codon.
What do anticodons do?
Anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids. Peptide bonds join the amino acids together. Each tRNA then leaves the ribosome as the polypeptide is formed.
How are different proteins expressed from one gene?
Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.
How is the shape of a protein formed?
Polypeptide chains fold to form the 3D shape of a protein, held together by hydrogen bonds and other interactions between individual amino acids. Proteins have a large variety of shapes which determines their functions.
