How Genes Direct the Production of Proteins Flashcards
What is it called when DNA is turned into RNA?
transcription
What is it called when RNA is turned into proteins?
translation
Is DNA or RNA more stable?
DNA
-if you look at RNA funny it will fall apart
-only make RNA when you need proteins in the cell
Which DNA strand is transcribed into RNA?
the 3’-5’ strand
In which direction is RNA made?
5’-3’
What is a gene?
segment of DNA that is transcribed into RNA and its associated transcriptional control regioins
What is mRNA?
messenger RNA
-translated into proteins
What is tRNA?
transfer RNA
-transfer AA to the growing peptide chain
What is rRNA?
ribosomal RNA
-encode ribosomal proteins
What is microRNA?
microRNAs
-block translation of specific mRNAs and thereby regulate gene expression
What is siRNA?
small interfering RNA
-turn off gene expression by directing the selective degradation of mRNA
What is snoRNA?
small nucleolar RNA
-process and chemically modify rRNA
What is scaRNA?
small cajal RNAs
-modify snoRNAs and snRNAs
What is the most abundant type of RNA?
rRNA (80%)
What percentage of RNA is tRNA?
15%
What percentage of RNA is mRNA?
3-5%
What is responsible for the transcription of most protein coding genes?
RNA polymerase II
Where do transcription factors bind to initiate transcription?
TATA box
do transcription factors regulate gene expression?
yes
Is RNA a linear molecule?
no, it associates with itself and makes secondary structures
-rory RNA cowboy
What does the TBP do?
recognize TATA box
*subunit of TFIID
What does TAF do?
recognize other DNA sequences near the transcription start point
*subunit of TFIID
What does TFIIB do?
recognize BRE element in promoters
-accurately positions RNA polymerase at start site
What does TFIIF do?
stabilizes RNA polymerase interactions with TBP and TFIIB
-helps attract TFIIE and TFIIH
What does TFIIE do?
attracts and regulates TFIIH
What does TFIIH do?
unwinds DNA at transcription start point
What does RNA polymerase I transcribe?
rRNA genes
What does RNA polymerase II transcribe?
all protein coding genes
What does RNA polymerase III transcribe?
tRNA
What is mRNA splicing ?
-preformed by splicesome which is largely made of snRNA complex with 7 protein subunits to form an SNP
-snRNAs involved in splicing
-snRNAs provide proper base pairing with mRNA*
-RNA-RNA arrangements are dynamic and shift through the splicing process*
What does splicing do?
remove introns
mutation in intron could lead to…
intron not being able to be spliced
What is alternative splicing?
splicing mRNAs in various ways to produce different combinations of exons depending upon the tissue and/or types of cells singlas
Characteristics of mature mRNA:
-spliced
-5’ cap (prevents it from unwinding)
-poly A tail
-exported from nucleus
How do miRNAs regulate translation?
-bind to 3’ UTR of target mRNA to form an RNA-inducing silencing complex
-suppress protein synthesis and/or induce mRNA degradation
-each miRNA can target multiple different mRNAs
What is a codon?
three base pair sequence that codes for an amino acid
important features of genetic code:
-read frame the beginning to end (reading frame is crucial)
-degenerate (more than one codon can bring in the same AA)
-third base in triplet codon is less specific than the first two
-3 of the 64 possible codons do not code for AA, but signal termination
what are the stop codons?
UAA
UAG
UGA
what is the start codon?
AUG
What is Roberts syndrome?
prenatal growth retardation, craniofacial abnormalities (microcephaly and cleft lip/palate) and limb formation
-homozygous mutation of ESCO2
-decrease rRNA transcription and lead to nucleolar morphology defects
-decreases protein synthesis
How can we affect gene expression without changing genetic code?
epigenetics
