Gene Structure Function - Lecture 9 Flashcards
What information does a gene contain?
○ Structural
○ Temporal
○ Positional
○ Inducible
What does structural information refer to?
Coding DNA
What does temporal information refer to?
Developmental - when a gene switches on
What does positional information refer to?
Tissue/cell specific - where a gene switches on e.g. insulin production
What does inducible information refer to?
Nutrients. stress, hormones - switching a gene on/off depending on the environment
In prokaryote genes, what does the promoter do?
○ Defines transcription start site and it’s direction
○ Where RNA polymerase binds
In prokaryote genes, what is a leader/spacer?
A section of DNA which is not translated
In prokaryote genes, what is a cistron?
○ Coding regions
○ Segments of DNA corresponding to one polypeptide
○ Have a start and stop codon
In prokaryote genes, what is a terminator?
Tells RNA polymerase to stop at that point
What does transcription of prokaryotic gene produce?
○ Polycistronic mRNA
○ Promoter not transcribed
What does translation of prokaryotic gene produce?
Polypeptides
How can several proteins be made?
○ Using multiple stop and start signals
○ Transcriptions start/stop sites are not the same as translation start/stop sites
In eukaryotic gene, what does the promoter do?
Same function as prokaryotes
In eukaryotic gene, what does the enhancer do?
○ Binding sites for transcription factors to boost activity of the gene
○ Can be anywhere on the gene
In eukaryotic gene, what are exons?
Include the mature mRNA
In eukaryotic gene, what are introns?
In primary transcript but removed from the mature transcript
What is splicing?
Introns removed and exons joined together
What does the mature mRNA include in eukaryotes?
○ 5’ UTR
○ Translated region
○ 3’ UTR
What is the size difference between eukaryotic and prokaryotic genes?
○ Eukaryotic genes can be quite large but most is non-coding
○ Lower eukaryotic genes and prokaryotic genes are small and equate more to the size of the polypeptides they produce
What is the coding strand?
○ Sense 5’ - 3’
○ Same direction that RNA polymerase travels
○ Has same sequence as RNA product
What is the template strand?
○ Antisense 3’ - 5’
○ RNA polymerase reads the template strand and uses it as a guide
○Sequence is complementary to RNA product
What happens in the transcription bubble?
○ RNA polymerase binds to DNA
○ Melts double strand
○ Polymerises 5’ to 3’ direction
○ RNA produced is a copy of the coding strand and complementary to template strand
What is the Pribnow box?
○ A conserved DNA sequence (TATAAATG) found in bacterial promoters
○ Located 10 nucleotides to the left of the transcription start site
○ Helps RNA polymerase to initiate transcription
