Molecular Diagnostics Quiz #1
Complete Answers
Where is the wobble position in a codon and why do we say it "wobbles"? -
ANSWER-The wobble position is the 3rd (last) base in a codon that can often be one
of any of the 4 nucleotides and still encode the same amino acid. There is less
fidelity required in this last position so a SNP at this location will not have an effect
on the protein.
How many possible codons are in the genetic code and how many amino acids does
this make? - ANSWER-There are 64 possible codons that encode 20 amino acids, 2
stop codons, and an UGA that can be either a stop codon or the amino acid
selenocysteine depending on the adjacent sequence
What is rRNA and what is its role in protein synthesis? - ANSWER-rRNA binds with
specific proteins to become the ribosome, which is essential for translation to occur.
The ribosome holds the mRNA and the 2 tRNAs in place, while forming a peptide
bond between the amino acids carried by the tRNAs.
tRNA - ANSWER-The cruciform structure of tRNA makes it look like a cross or 3-leaf
clover. One end has the anti-codon to complement the mRNA codon, and the other
end carries the appropriate amino acid. Two tRNAs can fit in one ribosome at the
same time.
Single nucleotide polymorphism (SNPs) - ANSWER-SNPs are a one base pair
change in nucleotide sequence between individuals. Many SNPs are not within
exons, so they do not affect proteins, and therefore don't lead to disease. If they are
in exons, and sit within the wobble position, they still may have no change on the
amino acid sequence of that protein. Only those SNPs that cause either a premature
termination of the protein or an amino acid substitution that alters the tertiary
structure of the protein would be linked to disease state.
Example:
Individual 1: AAATTTTAA
Indivdual 2: AAATATTAA (the underlined sequence is the SNP
Short tandem Repeat (STRs) - ANSWER-STRs (short tandem repeats) are
sequences 1-13 bp in length that are copied multiple time.
Example:
ATCATCATCATCATC - is a 3 bp sequence -ATC- copied 5 times.
Variable number tandem repeats (VNTRs) - ANSWER-VNTRs (variable number
tandem repeats) only differ in the fact that the sequence that is repeated is 14-500
bps long instead of 1-13.
Micro RNAs (miRNA) - ANSWER-regulatory RNAs
Complete Answers
Where is the wobble position in a codon and why do we say it "wobbles"? -
ANSWER-The wobble position is the 3rd (last) base in a codon that can often be one
of any of the 4 nucleotides and still encode the same amino acid. There is less
fidelity required in this last position so a SNP at this location will not have an effect
on the protein.
How many possible codons are in the genetic code and how many amino acids does
this make? - ANSWER-There are 64 possible codons that encode 20 amino acids, 2
stop codons, and an UGA that can be either a stop codon or the amino acid
selenocysteine depending on the adjacent sequence
What is rRNA and what is its role in protein synthesis? - ANSWER-rRNA binds with
specific proteins to become the ribosome, which is essential for translation to occur.
The ribosome holds the mRNA and the 2 tRNAs in place, while forming a peptide
bond between the amino acids carried by the tRNAs.
tRNA - ANSWER-The cruciform structure of tRNA makes it look like a cross or 3-leaf
clover. One end has the anti-codon to complement the mRNA codon, and the other
end carries the appropriate amino acid. Two tRNAs can fit in one ribosome at the
same time.
Single nucleotide polymorphism (SNPs) - ANSWER-SNPs are a one base pair
change in nucleotide sequence between individuals. Many SNPs are not within
exons, so they do not affect proteins, and therefore don't lead to disease. If they are
in exons, and sit within the wobble position, they still may have no change on the
amino acid sequence of that protein. Only those SNPs that cause either a premature
termination of the protein or an amino acid substitution that alters the tertiary
structure of the protein would be linked to disease state.
Example:
Individual 1: AAATTTTAA
Indivdual 2: AAATATTAA (the underlined sequence is the SNP
Short tandem Repeat (STRs) - ANSWER-STRs (short tandem repeats) are
sequences 1-13 bp in length that are copied multiple time.
Example:
ATCATCATCATCATC - is a 3 bp sequence -ATC- copied 5 times.
Variable number tandem repeats (VNTRs) - ANSWER-VNTRs (variable number
tandem repeats) only differ in the fact that the sequence that is repeated is 14-500
bps long instead of 1-13.
Micro RNAs (miRNA) - ANSWER-regulatory RNAs
