1. A molecule that DNA is composed of 2 strands that form a twin helix structure.

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DNA is a macromolecule consist of of two strands that twist about a usual axis in a shape called a double helix. The dual helix looks like a twisted ladder—the rungs that the ladder are composed of bag of nitrogenous bases (base pairs), and also the political parties of the ladder are comprised of alternate sugar molecules and also phosphate groups.

Molecules that DNA selection in size from thousands of thousands to numerous base pairs. The the smallest chromosome in the person genome, Chromosome 21, has approximately 48 million base pairs.



DNA

A molecule of DNA has two strands, created of nucleotides, that kind a double helix shape.

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2. Every DNA strand is created of nucleotides—units comprised of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

Each strand the DNA is a polynucleotide written of units called nucleotides. A nucleotide has actually three components: a sugar molecule, a phosphate group, and a nitrogenous base.

The street in DNA’s nucleotides is dubbed deoxyribose—DNA is one abbreviation for deoxyribonucleic acid. RNA molecules use a different sugar, called ribose. Covalent bonds sign up with the street of one nucleotide to the phosphate group of the following nucleotide, forming the DNA strand’s sugar-phosphate backbone.

A nitrogenous base is an necessary molecule that has nitrogen and also has the chemistry properties that a base. Over there are 4 nitrogenous bases that occur in DNA molecules: cytosine, guanine, adenine, and also thymine (abbreviated together C, G, A, and also T). RNA molecules contain cytosine, guanine, and adenine, however they have actually a different nitrogenous base, uracil (U) instead of thymine.

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3. The order of nitrogenous bases on the two strands the a DNA molecule room complementary.

The succession of nitrogenous bases top top one strand the a DNA molecule’s twin helix matches up in a particular means with the succession on the other strand. Adenine pairs with thymine and cytosine pairs through guanine.

Why execute the nitrogenous bases pair in this details way? The bases on each strand room joined to the bases top top the various other strand through hydrogen bonds, yet different bases have different chemical structures. Cytosine and thymine (and uracil in RNA) room pyrimidines, comprise one ring. Adenine and also guanine space purines, containing two rings. The pyrimidines pair v the purines: cytosine and guanine type three hydrogen bonds, and adenine and thymine type two.

4. Specific sequences the nitrogenous bases that password for certain proteins or regulatory RNA molecules are referred to as genes.

Each strand the DNA is prefer a recipe publication for synthesizing proteins. Certain sequences that nitrogenous bases along the strand encode specific RNA molecules. This sequences are called genes. MRNA molecule transcribed from gene are translated into proteins later.

Chromosomes can vary commonly in their number of base pairs and also genes. The longest chromosome in human being cells, Chromosome 1, is roughly 249 million base pairs long and has in between 2000 and also 2100 distinct genes. Chromosome 21, the shortest human being chromosome, consists of 48 million base pairs and contains between 200 and 300 genes. Overall, prokaryotic cells have much shorter chromosomes with fewer genes. Because that example, the bacterium Carsonella rudii has actually only 159,662 basic pairs and also 182 genes in its entire genome.

Although genes get most that the credit for what DNA does, they comprise only around 1% the DNA (in humans). Genes room separated indigenous one an additional by order of nitrogenous bases the don’t administer instructions because that RNA synthesis. These are called intergenic regions. Also within genes, there are areas of noncoding DNA referred to as introns.

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Noncoding areas of DNA are important since they administer binding sites for proteins that aid activate or deactivate the procedure of transcription. They can also carry out protection because that the coding regions. For instance, telomeres consist of of recurring sequences that defend the hereditary information on each DNA molecule from being damaged throughout cell division.