Genetic Implications of DNA Structure

Avery's work demonstrated that DNA is the transforming principle and contains the genotype.

Watson and Crick elucidated the chemical structure of DNA, enabling the study of genetic information at a molecular level.

The base sequence encodes genetic instructions that determine the phenotype.

<p>Genetic material must carry large amounts of information and replicate faithfully.</p> Signup and view all the answers

<p>Watson and Crick proposed that DNA strands unzip and each strand serves as a template for synthesizing a new complementary strand.</p> Signup and view all the answers

<p>The double helix provided a chemical basis for the genetic code and suggested how genetic information could be replicated.</p> Signup and view all the answers

<p>Specific base pairing ensures that only the complementary sequence can be synthesized during DNA replication.</p> Signup and view all the answers

<p>Their model allowed geneticists to examine genes directly rather than inferring information from phenotypic consequences.</p> Signup and view all the answers

<p>The DNA copying enzyme does not permit the incorporation of nonstandard base pairs.</p> Signup and view all the answers

<p>Hydrogen bonds are approximately 0.3 nm long and weaker, whereas covalent bonds are about 0.095 nm long and much stronger.</p> Signup and view all the answers

<p>Adenine forms two hydrogen bonds with thymine, while cytosine forms three hydrogen bonds with guanine.</p> Signup and view all the answers

<p>The 2500 hydrogen bonds per kilobase provide extraordinary stability to the DNA double helix.</p> Signup and view all the answers

<p>Stacked bases in the DNA double helix are spaced approximately 0.34 nm apart.</p> Signup and view all the answers

<p>The A form is wider and shorter than the B form, with a wider major groove and a narrower minor groove.</p> Signup and view all the answers

<p>The major and minor grooves provide binding surfaces for DNA-binding proteins to read the sequence of bases.</p> Signup and view all the answers

<p>The x-ray diffraction pattern shows that there are about 10 to 10.5 base pairs per turn of the helix.</p> Signup and view all the answers

<p>The DNA double helix consists of two antiparallel polynucleotide strands with sugar-phosphate backbones on the outside and nitrogenous bases stacked in the interior.</p> Signup and view all the answers

<p>Base pairing ensures A always bonds with T and G always bonds with C, which maintains the stability of the double helix and allows accurate DNA replication.</p> Signup and view all the answers

<p>The hydrogen bonds between base pairs provide significant stability, with A-T pairs forming two hydrogen bonds and G-C pairs forming three.</p> Signup and view all the answers

<p>The two strands in the DNA double helix are oriented in an antiparallel fashion, meaning one strand runs in the 5’-3’ direction while the other runs in the 3’-5’ direction.</p> Signup and view all the answers

<p>Hydrophobic interactions and van der Waals forces between stacked adjacent base pairs further stabilize the DNA double helix.</p> Signup and view all the answers

<p>Watson-Crick base pairs refer to the specific pairing of A with T and G with C, which is essential for maintaining the integrity and function of DNA.</p> Signup and view all the answers

<p>Yes, non-standard base pairs can theoretically form, such as guanine pairing with thymine and cytosine pairing with thymine, although they are not typical in natural DNA.</p> Signup and view all the answers

<p>High-resolution x-ray diffraction studies and the chemical synthesis of uniform short DNA molecules have significantly advanced our understanding of DNA structure.</p> Signup and view all the answers

<p>Bending DNA is critical for the dense packing of DNA within chromatin, which is essential for DNA organization in eukaryotic cells.</p> Signup and view all the answers

<p>DNA is more stable than RNA because it lacks the 2'-hydroxyl group, which in RNA makes it susceptible to hydrolysis.</p> Signup and view all the answers

<p>The 2'-hydroxyl group in RNA contributes to the slow hydrolysis of phosphodiester bonds, making RNA less stable than DNA.</p> Signup and view all the answers

<p>The absence of the 2'-hydroxyl group in DNA prevents the hydrolysis of its phosphodiester bonds, enhancing its stability.</p> Signup and view all the answers

<p>A primary concern was that the proposed structure's negatively charged phosphates would repel each other without the presence of acidic hydrogen atoms to stabilize it.</p> Signup and view all the answers

<p>Fraver's model proposed that the phosphates are on the outside, while the bases are on the inside, linked by hydrogen bonds.</p> Signup and view all the answers

<p>If van der Waals distances are too small, it may indicate potential errors in the proposed structure, impacting its biological significance.</p> Signup and view all the answers

<p>The phrase indicates that DNA is in a stable ionic form, which contributes to its biological interactions and stability.</p> Signup and view all the answers

<p>It suggests a possible copying mechanism for the genetic material.</p> Signup and view all the answers

<p>The ratios are always very close to unity.</p> Signup and view all the answers

<p>The extra oxygen in ribose would create too close van der Waals contacts.</p> Signup and view all the answers

<p>He provided constant advice and criticism on interatomic distances.</p> Signup and view all the answers

<p>It describes the double helix structure of deoxyribose nucleic acid.</p> Signup and view all the answers

<p>The data were insufficient for a rigorous test of the proposed structure.</p> Signup and view all the answers

<p>It celebrated its 50th anniversary.</p> Signup and view all the answers

<p>They based it mainly on published experimental data and theoretical arguments.</p> Signup and view all the answers

<p>A - DNA requires 75% H₂O, while B - DNA requires 92% H₂O.</p> Signup and view all the answers

<p>Z - DNA has a left-handed helix direction, whereas both A - DNA and B - DNA are right-handed.</p> Signup and view all the answers

<p>A - DNA has 11 base pairs per turn, while B - DNA has 10. This difference may affect the packing and stability of DNA during processes like replication.</p> Signup and view all the answers

<p>The distance between adjacent bases in A - DNA is 0.26 nm, while in B - DNA it is 0.34 nm.</p> Signup and view all the answers

<p>A - DNA has a short and wide shape, while B - DNA has a long and narrow shape.</p> Signup and view all the answers

The study of genes at the chemical and molecular level.

DNA's structure holds the genetic instructions, determining traits.

The order of DNA bases (A, T, C, G) that carries genetic code.

The process of making a new DNA molecule from an existing one.

Two DNA strands that pair up due to base pairing rules (A-T, G-C).

Weak bonds that hold the two DNA strands together.

The double helix structure of DNA, showing how genes work.

The instructions encoded into the order of DNA bases.

DNA forms a double helix with two polynucleotide strands. The sugar-phosphate backbones are on the outside, and the bases face inward.

A always pairs with T, and G always pairs with C, held together by hydrogen bonds.

The two DNA strands run in opposite directions (5' to 3' and 3' to 5').

The standard A-T and G-C pairings in DNA.

Two DNA strands where all nucleotides form base pairs.

The stability of DNA is due to many hydrogen bonds between base pairs and hydrophobic interactions.

Base pairs other than standard A-T and G-C, possible but uncommon in natural DNA.

A technique used to study DNA structure of high resolution, using DNA crystals.

Adenine pairs with thymine (A-T) via 2 hydrogen bonds, and cytosine pairs with guanine (C-G) via 3 hydrogen bonds

DNA consists of two strands forming a twisted ladder-like structure

Uneven grooves on the exterior of the DNA double helix, exposing base edges.

Most common DNA structure in cells; a right-handed helix with 10-10.5 base pairs per turn.

GC base pairs are more stable (thermodynamically) than AT base pairs.

The sequence of bases in the DNA determines which atoms along the grooves are exposed for protein interactions.

DNA is the primary carrier of genetic information due to its high stability, allowing for long-term storage.

Chromatin is a complex of proteins and DNA, densely packing DNA in eukaryotic cells.

A chemical bond that links nucleotides together in DNA and RNA.

The sugar component of DNA.

A chemical reaction where a molecule is broken down by adding water.

A proposal of a double-helix structure that describes the salt of deoxyribose nucleic acid (DNA).

Specific pairs of DNA bases always bond together: adenine (A) with thymine (T), and guanine (G) with cytosine (C).

The sugar molecule found in DNA, making it distinct from RNA.

A form of DNA that exists in low hydration conditions (about 75% water). It has a shorter and wider structure compared to B-DNA.

The most common form of DNA found in cells, with a right-handed helical structure. It has a high water content (92%) and a long and narrow shape.

A DNA form with a left-handed helix, formed under specific conditions (alternating purine/pyrimidine bases). It is elongated and narrow.

The direction of the DNA helix can be either right-handed (clockwise) or left-handed (counter-clockwise). B-DNA is right-handed, while Z-DNA is left-handed.

The number of base pairs that make a complete turn in the DNA helix. Different DNA forms have different numbers: B-DNA has 10, A-DNA has 11, and Z-DNA has 12.