Chapter 3: The Human Genome: Gene Structure and Function Flashcards
the amplification of genetic information goes from what to where?
from genome to proteome to gene networks, and ultimately to cellular function
What are introns?
pre-mRNA that is transcribed in the nucleus not present in mature RNA
What are exons?
segments of genes that actually encode for the amino acid sequence of the protein
What are the structural features of a human gene?
5' promotor enhancer silcener repressor 3' UTR containing AATAAA signal for polyadenylation
What are gene families?
they share closely related DNA and amino sqequences
What is an example of a gene family?
Beta-globin cluster on chromosome 11 and alpha-globin cluster on chromosome 16
What are psuedogenes?
DNA sequences that resemble known genes but are nonfunctional. They lack introns
What are the two types of psuedogenes?
1) non-processed-nonfunctional “dead” genes
2) processed- arise from retrotansposition
How does retrotransposition occur?
reverse transcription of a DNA copy of mRNA and later integration of the DNA copy back into the genome
What is an important class of noncoding RNA genes?
miRNA genes
What do miRNA genes do?
they control expression and repression of other genes during development
How does initiation of transcription occur?
by influence of the promoter
Where is the start site of RNA?
on the 5’ UTR
What is RNA splicing?
removal of introns and splicing together exons
Which nucleotides are introns rich in?
GT
Which nucleotides are exons rich in?
AG
What directionality does protein translation have?
amino to carboxyl terminus
How is the beta-globin gene transcribed?
from telomere to centromere
The TATA box is rich in which nucleotides?
A’s and T’s
What does the TATA box do?
determines the start of transcription
What does the CAT box do?
it is the second conserved region upstream of TATA
What happens if there is a mutation in either the TATA or the CAT box?
It would cause a reduction in transcription
What are the two components of the promoter?
TATA box and CAT box
What are housekeeping genes?
repeated regions of CPG island; they lack TATA or CAT boxes
What inhibits or silences the function of housekeeping genes?
hypermethylation of the CPG islands
The promoters of housekeeping genes are rich in what nucleotides?
CG
What is an example where silencing of a housekeeping gene is necessary?
hypermetylation of a second X chromosome in women
What is meant by degenerate?
some amino acids are coded by multiple codons
What are enhancers?
They are an activating sequence that act at a distance to stimulate transcription
What is the Locus Control Region?
establishes proper upper chromatin context for high-level expression, located upstream
How is RNA splicing guided?
specific sequences in the primary RNA transcript
What establishes the reading frame of the mRNA
AUG
What is somatic rearrangement
the cutting and pasting of DNA sequences in lymphocyte precursor cells to rearrange genes to generate antibody diversity
What is allelic exclusion?
only 1 or 2 of parental alleles of autosomal loci are expressed
