Unit 1 - KA 3 Flashcards
(12 cards)
What is gene expression?
Process by which specific genes ars activated to produce a required protein
Why are genes expressed?
To produce proteins which determine the phenotype of an individual
What does gene expression involve?
Transcription and translation
What the 3 types of RNA involved in translation and transcription?
mRNA, tRNA and rRNA
What is RNA?
Single stranded and is composed of nucleotides containing ribose sugar, phosphate and a base
What are the RNA bases?
Cytosine
Guanine
Adenine
Uracil
Where does transcription occur?
In the nucleus of a human cell
What is a codon?
Each triplet of bases on the DNA within a gene
What are the types of codons and what do they indicate?
Start codons indicates where transcription begins and stop codons signals where it ends
What happens during transcription?
The enzyme RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between bases.
RNA polymerase synthesises a primary transcript of mRNA from free RNA nucleotides by alinging them against their complementary base pair partners. Uracil is aligned against adenine
What are introns and exons?
Introns are non coding regions and exons are coding regions of RNA
What is the process of RNA splicing?
Introns are identified and removed from the transcript by enzymes.
The order of exons is unchanged during splicing and the spliced exons form a mature mRNA transcript.
Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.
Different proteins are expressed from one gene as a result of alternative RNA splicing
Each mature mRNA transcript carry a complementary copy of the DNA sequences from the nucleus to the cytoplasm, to be translated into proteins by ribosomes.
