DNA Structure and History Quiz

<p>Species Y due to higher G+C content (B)</p> Signup and view all the answers

<p>36% (A)</p> Signup and view all the answers

<p>Friedrich Miescher (A)</p> Signup and view all the answers

<p>Avery and his colleagues' work with Streptococcus pneumoniae (C)</p> Signup and view all the answers

<p>A = T and G = C (B)</p> Signup and view all the answers

<p>A right-handed double helix (C)</p> Signup and view all the answers

<p>They pair specific bases with one another. (D)</p> Signup and view all the answers

<p>That DNA carries genetic information, not protein (B)</p> Signup and view all the answers

<p>It remains constant in different tissues. (D)</p> Signup and view all the answers

<p>He provided evidence supporting DNA as the genetic material. (B)</p> Signup and view all the answers

<p>Adenine and Thymine (B)</p> Signup and view all the answers

<p>The most stable form under physiological conditions (B)</p> Signup and view all the answers

<p>They are more stable (A)</p> Signup and view all the answers

<p>The potential for hairpin or cruciform structures (C)</p> Signup and view all the answers

<p>They cannot form cruciform structures (B)</p> Signup and view all the answers

<p>They have different geometric configurations (A)</p> Signup and view all the answers

<p>They provide significant stability to the double helix (C)</p> Signup and view all the answers

<p>Hairpin structure (D)</p> Signup and view all the answers

In DNA, adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

The percentage of adenine (A) in a DNA molecule equals the percentage of thymine (T), and the percentage of guanine (G) equals the percentage of cytosine (C).

The temperature at which a double-stranded DNA molecule separates into two single strands.

DNA with a higher proportion of guanine (G) and cytosine (C) base pairs has a higher melting temperature (Tm) because G-C base pairs have three hydrogen bonds, while A-T base pairs have two.

Organisms that thrive in extremely hot environments, often having DNA with a high G+C content to stabilize their DNA at high temperatures.

Adenine always pairs with thymine, and guanine always pairs with cytosine in DNA. These pairings are based on the specific shapes and chemical properties of the bases, allowing for precise hydrogen bonding between them.

The double helix structure of DNA is stabilized by two main forces: hydrogen bonds between complementary base pairs, and base stacking interactions between adjacent bases.

DNA with a higher G≡C content is more stable than DNA with a higher A═T content. This is because the base stacking interactions between consecutive G≡C pairs are stronger than those between A═T pairs.

The B-form is the most common and stable form of DNA under physiological conditions. Its structure is characterized by a right-handed helix with a specific diameter and spacing between bases.

A palindrome in DNA refers to a sequence where the same base sequence is present on both strands of DNA, but in opposite directions. These sequences can form hairpins or cruciform structures.

Hairpins are single-stranded DNA or RNA structures that form when a palindromic sequence folds back on itself. These structures are stabilized by intrastrand hydrogen bonding.

Cruciform structures are formed when palindromic sequences in double-stranded DNA fold back on themselves. These structures involve both strands of the DNA and are stabilized by intrastrand hydrogen bonding.

Mirror repeats are similar to palindromes but occur within a single strand of DNA. They do not have complementary sequences within the same strand and cannot form hairpin or cruciform structures.

Friedrich Miescher isolated and characterized a phosphorus-containing substance in 1869, calling it "nuclein." This substance was later identified as DNA.

Oswald Avery, Colin MacLeod, and Maclyn McCarty conducted experiments in the 1940s to prove that DNA, not protein, is the genetic material. They demonstrated this by transferring genetic information from a virulent strain of bacteria to a non-virulent strain using extracted DNA.

Erwin Chargaff discovered that the amounts of certain nitrogenous bases in DNA are always equal (A=T, G=C). These rules guided the understanding of DNA structure and base pairing.

DNA consists of two long chains of nucleotides, spiraling around a central axis. The chains run in opposite directions, creating a structure known as a double helix.

Each nucleotide consists of a sugar molecule, a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).

The two strands of DNA are complementary, meaning that A always pairs with T and G always pairs with C. This specific base pairing helps maintain the double helix structure and ensures accurate DNA replication.

The sequence of bases in a DNA strand holds the genetic information that determines an organism's traits. This information is passed on to offspring during cell division.

James Watson and Francis Crick proposed the double helix model of DNA in 1953, based on the accumulated knowledge about DNA structure and Chargaff's rules, which helped revolutionize our understanding of genetics and molecular biology.