AAB Molecular Diagnostics- Nicole's questions and answers

Nucleic Acid grows by attachment of 5' phosphate group of the incoming nucleotide to the 3'hydroxyl group of the last nucleotide double stranded DNA most energetically favorable state for DNA Purines double-ring structure Adenine (A) + Guanine (G) Pyrimidine single-ring structure Uracil (U)+ Cytosine Messenger RNA (mRNA) -template for all protein synthesis -encode all information necessary to produce proteins Heterogeneous nuclear RNA primary product of transcription with introns & exons Ribosomal RNA (rRNA) -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) functions in eukaryotic splicing microRNA (miRNA) single-stranded RNA involved in transcriptional regulation Catalytic RNA 4 base RNA strands capable of catalyzing chemical reactions small interfering RNA (siRNA) functional intermediates of RNA interference small activating RNA (saRNA) double-stranded RNA that induces gene expression at transcriptional level, a phenomenon named small RNA induced gene activation (RNAa) DNA ligase joins DNA fragments formed by discontinuous synthesis in DNA replication or by DNA repair pathways Nucleases -"digest" nucleic acid molecules by breaking phosphodiester bonds -may be single or double stranded, DNA, RNA, or RNA specificity -have nuclease activity Endonucleases digest nucleic acids from/in the middle of the molecule Exonucleases digest nucleic acids beginning at a free-end and may require a 3' or 5' end Restriction endonucleases bacterial endonucleases that recognize specific short DNA base pair sequences and cleave the DNA molecule only at the recognition site DNA methyltransferases adds methyl group to cytosine or adenine DNA nucleotides The location of DNA methyltransferases occurs mainly at the C5 section of CpG dinucleotides (mammals) Helicases -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 enzymes with both nucleases and ligase activity that change the amount of supercoiling in DNA Gyrase relaxes positive supercoils and allows superhelical tension ahead of the polymerase to be released during DNA replication Polymerases (RNA + DNA) -polymerases join DNA or RNA nucleotide together to form a single-stranded daughter using a stretch of single-stranded parent molecule as a template -typically perform synthesis according to base pair rules and proceed in the 5' to 3' direction Reverse transcriptase mostly of viral origin; catalyzes the synthesis of DNA from either a DNA or RNA template What degrades DNA? exonucleases Exonuclease I degrades single stranded DNA from 3' hydroxyl end Exonuclease III degrades 5' mononucleotides from 3' end of double stranded DNA Exonuclease VII digests single stranded DNA from either end Mung Bean nuclease digests single stranded DNA or RNA S1 nuclease breaks single stranded DNA or RNA into 5' mononucleotide recBC nuclease ATP-dependent single & double stranded DNA nuclease; degrades from either end micrococcal nuclease digest single & double stranded DNA or RNA @ AT-AU rich regions DNase I digests single & double strands DNA at pyrimidines 2 types of Eukaryotic methylation (DNA methyltransferases) & describe 1. Maintenance: work throughout life of cell 2. De Novo: work during embryonic development Central dogma replication --> transcription .--> translation Autosomes 22 pairs/cell non-sex linked genetic heredity info Sex chromosomes 1 pair/cell genetic traits linked to a person's gender Nucleosome DNA double helix is wrapped around the histone octamer containing 2 copies of each histone H2A, H2B, H3 & H4 Linker histone H1 binds the DNA between nucleosomes forming chromatin