lecture 23 Flashcards
gene complexity and structure
what is the C value paradox?
excess DNA is present in the genome that does not seem to be essential for the development or evolutionary divergence of an organism
what paradox does the onion test refer to?
C-value paradox
what is C-value?
genome size
what is the g-value paradox?
the number of genes doesn’t have a correlation with organismal complexity
how are humans more complex than other organisms that have more DNA?
through alternative splicing and transcription factors
where does highly repetitive DNA occur?
heterochromatic regions(i.e., telomeres, centromeres)
what type of DNA is found in euchromatin?
moderately repetitive DNA and unique DNA
what are the purposes of moderately repetitive DNA?
length mutability, modulation of transcription factor binding, spacing between promoter elements, cytosine methylation, alternative splicing, mRNA stability, transcription start and termination sites, etc.
what is single copy DNA?
unique DNA; coding DNA; low copy number
what are exons?
“coding sequences,” determines phenotype
what are introns?
“intervening sequences” = areas of genes that generally don’t code for phenotype
is the 5’ region of mRNA that is directly upstream from the initiation codon translated?
no, it is the 5’ UNtranslated region
is the 3’ section of mRNA that immediately follows the translation termination codon translated?
no, it is the 3’ UNtranslated region
what is the dna sequence onto which the transcription machinery bins and initiates transcription?
promotor
what is the highly conserved sequence in DNA serving as the binding site for transcription factor binding?
TATA box
what is the consensus sequences that occurs upstream by 60-100 bases to the initial transcription site?
CAAT box
what is the region of DNA that can be bound with proteins (activators) to activate transcription of a gene or genes?
GC box
what do the GC box and CAAT box make up?
promotor proximal elements
what is the section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription?
terminator
what is a set of several similar genes, formed by duplication of a single original gene, and generally with similar biochemical functions?
multigene family
where are the genes in multigene families located relative to each other?
in similar regions of the same chromosome
are the genes of multigene families used/synthesized at the same time?
no
what are dysfunctional relatives of genes that have lost their protein‐coding ability?
pseudogenes
what are multiple copies of small genes clustered throughout the genome at specific sites in high copy number?
repeated genes
what type of genes are the genes that code for tRNA and mRNA? why?
repeated genes because so many tRNAs and mRNAs are needed
does the terminator sequences occur before or after the poly-A tail?
after
