AAB MOLECULAR DIAGNOSTICS STUDY
GUIDE 2026 VERIFIED QUESTIONS AND
SOLUTIONS
◉ double stranded DNA.
Answer: most energetically favorable state for DNA
◉ Purines.
Answer: double-ring structure Adenine (A) + Guanine (G)
◉ Pyrimidine.
Answer: single-ring structure Uracil (U)+ Cytosine
◉ Messenger RNA (mRNA).
Answer: -template for all protein synthesis
-encode all information necessary to produce proteins
◉ Heterogeneous nuclear RNA.
Answer: primary product of transcription with introns & exons
,◉ Ribosomal RNA (rRNA).
Answer: -non-coding RNA
-component of the ribosomes, the protein synthetic factories in the
cell
-Eukaryotes ribosomes contain 2 subunits (60Ss & 40s)
◉ Small nuclear RNA (snRNA).
Answer: functions in eukaryotic splicing
◉ microRNA (miRNA).
Answer: single-stranded RNA involved in transcriptional regulation
◉ Catalytic RNA.
Answer: 4 base RNA strands capable of catalyzing chemical
reactions
◉ small interfering RNA (siRNA).
Answer: functional intermediates of RNA interference
◉ small activating RNA (saRNA).
Answer: double-stranded RNA that induces gene expression at
transcriptional level, a phenomenon named small RNA induced gene
activation (RNAa)
,◉ DNA ligase.
Answer: joins DNA fragments formed by discontinuous synthesis in
DNA replication or by DNA repair pathways
◉ Nucleases.
Answer: -"digest" nucleic acid molecules by breaking
phosphodiester bonds
-may be single or double stranded, DNA, RNA, or RNA specificity
-have nuclease activity
◉ Endonucleases.
Answer: digest nucleic acids from/in the middle of the molecule
◉ Exonucleases.
Answer: digest nucleic acids beginning at a free-end and may
require a 3' or 5' end
◉ Restriction endonucleases.
Answer: bacterial endonucleases that recognize specific short DNA
base pair sequences and cleave the DNA molecule only at the
recognition site
, ◉ DNA methyltransferases.
Answer: adds methyl group to cytosine or adenine DNA nucleotides
◉ The location of DNA methyltransferases.
Answer: occurs mainly at the C5 section of CpG dinucleotides
(mammals)
◉ Helicases.
Answer: -use the chemical energy in nucleoside triphosphates
-predominantly ATP, to break hydrogen bonds between bases and
unwind the DNA double helix into single strands
◉ Topoisomerases.
Answer: enzymes with both nucleases and ligase activity that
change the amount of supercoiling in DNA
◉ Gyrase.
Answer: relaxes positive supercoils and allows superhelical tension
ahead of the polymerase to be released during DNA replication
◉ Polymerases (RNA + DNA).
GUIDE 2026 VERIFIED QUESTIONS AND
SOLUTIONS
◉ double stranded DNA.
Answer: most energetically favorable state for DNA
◉ Purines.
Answer: double-ring structure Adenine (A) + Guanine (G)
◉ Pyrimidine.
Answer: single-ring structure Uracil (U)+ Cytosine
◉ Messenger RNA (mRNA).
Answer: -template for all protein synthesis
-encode all information necessary to produce proteins
◉ Heterogeneous nuclear RNA.
Answer: primary product of transcription with introns & exons
,◉ Ribosomal RNA (rRNA).
Answer: -non-coding RNA
-component of the ribosomes, the protein synthetic factories in the
cell
-Eukaryotes ribosomes contain 2 subunits (60Ss & 40s)
◉ Small nuclear RNA (snRNA).
Answer: functions in eukaryotic splicing
◉ microRNA (miRNA).
Answer: single-stranded RNA involved in transcriptional regulation
◉ Catalytic RNA.
Answer: 4 base RNA strands capable of catalyzing chemical
reactions
◉ small interfering RNA (siRNA).
Answer: functional intermediates of RNA interference
◉ small activating RNA (saRNA).
Answer: double-stranded RNA that induces gene expression at
transcriptional level, a phenomenon named small RNA induced gene
activation (RNAa)
,◉ DNA ligase.
Answer: joins DNA fragments formed by discontinuous synthesis in
DNA replication or by DNA repair pathways
◉ Nucleases.
Answer: -"digest" nucleic acid molecules by breaking
phosphodiester bonds
-may be single or double stranded, DNA, RNA, or RNA specificity
-have nuclease activity
◉ Endonucleases.
Answer: digest nucleic acids from/in the middle of the molecule
◉ Exonucleases.
Answer: digest nucleic acids beginning at a free-end and may
require a 3' or 5' end
◉ Restriction endonucleases.
Answer: bacterial endonucleases that recognize specific short DNA
base pair sequences and cleave the DNA molecule only at the
recognition site
, ◉ DNA methyltransferases.
Answer: adds methyl group to cytosine or adenine DNA nucleotides
◉ The location of DNA methyltransferases.
Answer: occurs mainly at the C5 section of CpG dinucleotides
(mammals)
◉ Helicases.
Answer: -use the chemical energy in nucleoside triphosphates
-predominantly ATP, to break hydrogen bonds between bases and
unwind the DNA double helix into single strands
◉ Topoisomerases.
Answer: enzymes with both nucleases and ligase activity that
change the amount of supercoiling in DNA
◉ Gyrase.
Answer: relaxes positive supercoils and allows superhelical tension
ahead of the polymerase to be released during DNA replication
◉ Polymerases (RNA + DNA).
