Structure of dna and rna - class-XI

Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since, they are composed of simpler units called as nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase either guanine (G), adenine (A), thymine (T), or cytosine (C) as well as a monosaccharide sugar called as deoxyribose and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. According to base pairing rules (A with T and C with G), hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA. So, nuclotides are building blocks of DNA and not glucose or aminoacid. Thus, the correct answer is option C.

Because the two strands of DNA are complementary, the sequence of one strand dictates the sequence of the other. This property is known as complementarity.

0 x 174 Bacteriophage : In this bacteriophage, DNA is rounded, closed and bangle shaped, the duplication pattern is different type in this bacteriophage.

All the bio-molecules are important for life but as per the question the nucleic acids stand out, because they only have genetic information coded in them and can pass on this information to next generation of cells. So, nucleic acid plays a significant role  in the basis of life. 

• In DNA transcription, the coding strand is the DNA strand whose base sequence corresponds to the base sequence of the RNA transcript produced (although with thymine replaced by uracil).
•  It is this strand which contains codons, while the non-coding strand contains anticodons.
•  Hence, UAG is triplet nitrogen base on m RNA, TAG will be the corresponding triplet on the coding strand. 
•  So, the correct answer is 'TAG'.

In eukaryotes DNA is tightly bound to histones which form a DNA protein particles called nucleosome. Each nucleosome contains 2 copies of each $H _{2A},H _{2B}.H _{3}$ and $H _{4}$ histone protein bounded on 146 BP of DNA.Each nucleosome bead is linked to next nucleosome bead by linker DNA.

The transforming principle in Griffith's experiment is DNA. Griffith conducted an experiment in 1928. In this experiment he chose two strains of Stephylococcus pneumoniae bacteria. One of them was a smooth strain which was virulent and the other one was a rough strain which was non-virulent. The smooth strains caused pneumonia when they were injected to the mice, and the rough strains did not cause pneumonia in mice. Griffith heat killed the smooth strain bacteria and injected them into mice and he observed that pneumonia was not caused in them. He mixed the heat killed smooth strain and rough strain and injected the mixture into mice and this mixture caused pneumonia in mice. When he tested the blood of the mice, he saw both rough and smooth strains of bacteria. This implied that some factor from the dead smooth bacterial strain had taken entry into the rough strains and converted them into smooth strains. He called this factor as Transforming principle.

DNA replication occurs during the S phase of interphase, which prepares the cell for subsequent mitotic division by doubling its genetic material.

In the double helix model, the two strands are coiled around a common axis.

The two complementary strands of a DNA double helix run in opposite directions, making them antiparallel, and their nitrogenous bases pair specifically via hydrogen bonds, making them complementary.

Higher DNA sequence similarity indicates a more recent common ancestor. Since A and B share 94% and C shares less with them, A and B are more closely related.

During transcription, RNA polymerase reads the template strand of DNA in the 3' to 5' direction so that the newly synthesized messenger RNA strand can be constructed in the 5' to 3' direction.

tRNA (transfer RNA) carries specific amino acids to the ribosome-mRNA complex during translation.

An anticodon is a triplet of nitrogenous bases on tRNA that is complementary to the codon on mRNA.

DNA replication requires both DNA polymerase (for synthesis) and DNA ligase (for joining fragments).

The pitch of one full turn of the B-DNA helix is 3.4 nm (or 34 Angstroms).

In double-stranded DNA, each base pair consists of two nucleotides. Therefore, 20,000 base pairs correspond to 40,000 nucleotides.

The genetic information in nucleic acids is encoded by the specific sequence or arrangement of nucleotides.

Helicase is the enzyme responsible for unwinding the DNA double helix by breaking the hydrogen bonds between complementary base pairs. Other enzymes like DNA polymerase and ligase are involved in synthesis and repair, while topoisomerase relieves supercoiling.

In the standard B-DNA model, one full turn of the helix spans 3.4 nm and contains 10 base pairs. Each base pair is separated by 0.34 nm.

Ligase joins DNA fragments (correct). Helicase breaks hydrogen bonds (correct). DNA polymerase synthesizes DNA by adding nucleotides, it does not cut DNA at specific sites (that is the function of restriction endonucleases).

Anticodons and codons are antiparallel. If the anticodon is 3'-UUUA-5', the complementary codon is read 5'-AAAU-3'.

The standard B-DNA double helix is characterized by right-handed coiling and antiparallel strands, meaning one runs 5' to 3' and the other 3' to 5'.

The two strands of the DNA double helix run in opposite directions, which is referred to as antiparallel polarity.

Chargaff's rules state that the amount of adenine equals thymine and guanine equals cytosine, which is a property of double-stranded DNA where base pairing occurs.

The length of the DNA is determined by the sugar-phosphate backbone. Removing nucleobases (the nitrogenous bases) does not change the physical length of the backbone chain.

The DNA double helix consists of two strands that are complementary (A-T, G-C) and run in opposite (antiparallel) directions.

Minisatellites are short sequences of DNA (10-60 base pairs) that are repeated many times in the genome, making them a classic example of highly repetitive DNA.

The DNA backbone consists of alternating deoxyribose sugar and phosphate groups, not ribose sugar (which is found in RNA).

The diameter of the B-DNA double helix is constant at 20 Angstroms (2 nm).

Single Nucleotide Polymorphisms (SNPs) represent variations at a single position in a DNA sequence among individuals.

The distance between two base pairs is 0.34 nm. For 1.7 meters of DNA, the number of base pairs is (1.7 m) / (0.34 x 10^-9 m/bp) = 5 x 10^9 bp.

Francis Crick was originally trained as a physicist before moving into molecular biology.

In the B-DNA model, the distance between adjacent base pairs is 0.34 nm (or 3.4 Angstroms).

There are 10 base pairs per turn (360 degrees). Therefore, the angle of deflection between two successive base pairs is 360 / 10 = 36 degrees.

UAC is a codon that codes for the amino acid Tyrosine. The other options are incorrect pairings or misidentifications of start/stop codons.

DNA polymerase cannot initiate synthesis de novo; it requires a short RNA primer synthesized by DNA primase to provide a free 3'-OH group.

In DNA, adenine always pairs with thymine via two hydrogen bonds. Thymine and Uracil are not base pairs, and the other options are incorrect.

Each base pair is 0.34 nm. 340 nm / 0.34 nm/bp = 1000 base pairs. Since each base pair consists of 2 nucleotides, 1000 base pairs = 2000 nucleotides.

In the Watson-Crick model, the sugar-phosphate backbones are on the outside, and the nitrogenous bases are projected inwardly to form hydrogen bonds.

Topoisomerases are enzymes that manage DNA supercoiling by cutting one or both strands of the DNA backbone to relieve torsional strain.

Translating the sequence TAC AA A GGG TTT CAA CCC: TAC (Methionine/Start), AAA (Phenylalanine), GGG (Proline), TTT (Lysine), CAA (Valine), CCC (Glycine). Note: The codon table mapping confirms this sequence.

RNA synthesis occurs in the 5' to 3' direction, and the template DNA strand is read in the 3' to 5' direction to ensure antiparallel alignment.

A palindromic DNA sequence reads the same in the 5' to 3' direction on both strands. Option C is not palindromic because the complementary strand of 5'-GGATCC-3' is 3'-CCTAGG-5', which does not match the provided sequence.

UGA, UAG, and UAA are known as stop or nonsense codons. They signal the termination of protein synthesis and do not code for any amino acid.

Insertion or deletion of a single nucleotide shifts the reading frame of the entire downstream genetic sequence, resulting in a frameshift mutation that drastically alters all subsequent amino acids and is usually lethal or severely dysfunctional. Substitutions or deletions of three nucleotides affect only single amino acids or remove a single codon.

Cytosine and guanine base pairs are held together by three hydrogen bonds, whereas adenine and thymine pairs have only two. Consequently, DNA strands with a higher G-C content require more thermal energy to break the hydrogen bonds, resulting in an increased melting temperature.

Successive nucleotides in both RNA and DNA chains are covalently joined together by phosphodiester bonds, which form between the 3 prime carbon of one sugar and the 5 prime carbon of the next. Glycoside bonds link bases to sugars, and hydrogen bonds hold complementary strands together non-covalently.

To protect plants from parasitic nematodes via RNA interference, transgenic host plants are engineered to express specific double-stranded RNA matching nematode genes. When the nematode feeds on the host plant, the ingested dsRNA triggers RNAi and silences the essential parasite genes.

The double helix structure of DNA was proposed by Watson and Crick, based on X-ray diffraction data provided by Rosalind Franklin and Maurice Wilkins. Wilkins is often credited alongside them.

During DNA replication, the lagging strand is synthesized discontinuously in short segments known as Okazaki fragments because DNA polymerase can only synthesize in the 5 prime to 3 prime direction. The leading strand, by contrast, is synthesized continuously.

The DNA double helix is stabilized by phosphodiester bonds in the backbone, base pairing between strands, and base stacking interactions.

Cytosine and guanine base pairs form three hydrogen bonds with each other in double-stranded DNA. In contrast, adenine and thymine pairs form only two hydrogen bonds.

Intercalation is the process where planar molecules slip between adjacent base pairs in the DNA double helix, causing distortion and frameshift mutations during replication. Depreciation, substitution, and mutation are unrelated or broader terms.

All three given statements are correct. E. coli contains circular double-stranded DNA, tobacco mosaic virus possesses single-stranded RNA, and reoviruses are known for having a double-stranded RNA genome.

Bacteriophage fX174 is a classic model organism known for having a single-stranded DNA genome. Most other common viruses feature double-stranded DNA or single/double-stranded RNA.

mRNA strand is complementary to template strand of DNA, while coding strand has same sequence as RNA (except thymine at the place of uracil). Hence, the sequence of bases in mRNA will be AUUCGAUG.

The DNA (Deoxyribonucleic acid) molecules have four nucleotide bases along with sugar and phosphate backbone, these four bases are adenine, guanine, thymine, and cytosine. Adenine and thymine are bonded together by two hydrogen bonds while guanine and cytosine are bonded by three hydrogen bonds.