1.5 Structure of the Genome Flashcards
What is a genome?
all the info within genes present in the DNA of a living organisms is called the genome
What is a gene?
a section of DNA containing a base sequence which codes for a protein is called a gene
What is the genome made up of?
both coding sequences called exons and non coding sequences called introns
What are the functions of introns?
regulation of transcription
protection
code that is transcribed but not translated
Regulation of transcription?
RNA polymerase, the enzyme that drives transcription is unable to initiate the process on its own. It needs the assistance of transcription factors
Regulation of transcription occurs when transcription factors that act as activator molecules attach to non-protein coding sequences which activate RNA polymerase
Bending of the DNA strands brings the regulator bearing the activators into contact with other transcription factors close to the promoter of the gene to be transcribed
this causes a molecular complex to form at the promoter sites (RNA polymerase, activators and transcription factors)
This causes transcription to begin
Protection?
some introns form repetitive sequences making up a protective structure called a telomere at each end of a chromosome
It prevents the chromosome from becoming damaged by fraying at its ends
Code that is transcribed but not translated?
Exons code for mRNA whose sequence of bases is translated into proteins
Some introns code for forms of RNA other than mRNA which are not translated into proteins; tRNA, rRNA and RNA fragments
RNA fragments?
small nuclear RNA (snRNA) form complexes with proteins and are involved in the removal of introns from primary transcript mRNA
Micro RNA (miRNA) are only about 22 nucleotides long but play an important role as post transcriptional regulators which bring about the silencing of genes
