2.4 Gene function - transcription and translation Flashcards
Define gene
A unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring
Define chromosome
A linear, highly compacted and organised DNA molecule, with associated proteins, which encodes genetic information
Define genome
The haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular organism
Name features of a eukaryotic gene
Promoter
Transcription start site
Exon
Intron
Termination sequence
Describe the process of transcription
1- After binding the promotor, the RNA polymerase opens up
DNA double helix (requires basal transcription factors, & topoisomerase I & II)
2- Exposed nucleotides on one strand act as template for complementary base pairing with incoming ribonucleoside-triphosphate monomers
3- No primer required: Growing chain extended 5’ to 3’ until a termination signal is reached
MRNA processing and termination requires:
5’ cap
3’ poly A tail addition
Termination
Splicing
Define genetic code
Codons in mRNA, Recognized by anticodons in tRNA
Define codon
Consists of 3 consecutive bases that specify a single amino acid
Define anticodon
Pairs with the codon on the mRNA, adding an amino acid on to the growing polypeptide chain
Define translation
Addition of amino acids to a polypeptide chain
What are the three main mechanisms of translation?
Elongation (addition of amino acids to polypeptide chain)
Initiation
Termination
What are the three sites in the ribosome and what are their functions?
E site: Holds a tRNA that will exit
P site: Holds the tRNA with growing polypeptide attached
A site: Holds an aminoacyl-tRNA
Name the three stages within the elongation cycle
Recognition
Peptide bond formation
Translocation
