A-DNA base sequences

CR Polymerase Chain Reaction. Widely used method for amplifying a DNA base sequence... 

Pribnow box a DNA base sequence that is part of a prokaryotic promoter it is located 10 bases before the transcription start site (11.2)... 

The first step in DNA sequencing is to cleave the enormous chain at known points to produce smaller, more manageable pieces, a task accomplished by the use of restriction endonucleases. Each different restriction enzyme, of which more than 3500 are known and approximately 200 are commercially available, cleaves a DNA molecule at a point in the chain where a specific base sequence occurs. For example, the restriction enzyme Alul cleaves between G and C in the four-base sequence AG-CT. Note that the sequence is a palindrome, meaning that the sequence (5 )-AGCT-(3 ) is the same as its complement (3 )-TCGA-(5 ) when both are read in the same 5 — 3 direction. The same is true for other restriction endonucleases. 

Restriction endonuclease (Section 28.6) An enzyme that is able to cleave a DNA molecule at points in the chain where a specific base sequence occurs. 

Intron DNA base sequence between exons, the protein-coding parts of a DNA sequence of a gene. Intronic sequences are transcribed into mRNA but they are spliced out of the RNA molecule before translation of RNA into protein (see also exon). 

In your notebook, invent your own restriction enzyme. Show the DNA base sequence where it cleaves. Then construct a double stranded section of DNA with at least 25 base pairs and mark the points of cleavage by your enzyme. Finally, show all fragments formed. 

In addition to probe length, other considerations in the selection of DNA probes include keeping the G-C composition to between 40 and 60%, and ensuring that no unusual base sequence is present, such as having no more than four at a stretch of a single base sequence (for example, -C-C-C-C-C-) or any other intraprobe complementary sequence that will reduce the specificity of the probe-sample target DNA interaction. 

No, only a small percentage of mutations cause genetic disorders—most have no impact on health or development. For example, some mutations alter a gene s DNA base sequence but do not change the function of the protein made by the gene. 

The seqnence of amino acids in proteins is nltimately encoded in the sequence of bases in DNA. Transcription encodes this information in mRNA molecules. Each RNA polymerase transcribes a very small part of the total DNA base sequence. It follows that RNA polymerases need specific places on DNA molecules to start and to stop transcription. Getting the amino acid seqnence right is critical for protein function. It follows that getting transcription started at precisely the right place is also critical. If the mRNA base sequence is not right, the amino acid sequence in the protein will not be right. 

All eukaryotic cells in our bodies contain the same 23 chromosomes with the same DNA base sequences. The lone differences are the mitochondria. The mitochondria in typical somatic cells contain less than 0.1% of the cell s DNA but in fertilized and dividing egg cells this number is greater. mtDNA is much smaller, often containing fewer than 20,000 base pairs. The value for humans is 16,569 base pairs. The mtDNA is a circular duplex. mDNA codes for the mitochondrial tRNAs and rRNAs but only a fraction of the mitochondrial proteins. Over 95% of the mitochondrial proteins are encoded by nuclear DNA. The mitochondria divide when the cell divides. 

Transcription It involves copying of DNA base sequences into a mRNA. A small portion of DNA double helix unwinds and are of the two DNA strands act as the template for the synthesis of /wRNA. Ribonucleotides assemble along the uncoiled template in accordance with the base pairing principle. For example, U in the RNA being formed appears opposite A of DNA C opposite G A opposite T and G opposite C of DNA. Then occurs the bond formation between the various nucleotides thus assembled. 

Sierra, L.M., Pastink, A., Nivard, M.J. Vogel, E.W. (1993) DNA base sequence changes induced... 

How can a DNA enhancer sequence located as many as several thousand base pairs from a gene transcription start site influence transcription even if its orientation is reversed ... 

Southern blotting—used to identify a specific base sequence in DNA. Northern blotting—used to identify specific base sequences in RNA. 

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