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What is the structural difference between purines and pyrimidines?

The purines in DNA are adenine and guanine, the same as in RNA. The pyrimidines in DNA are cytosine and thymine; in RNA, they are cytosine and uracil. Purines are larger than pyrimidines because they have a two-ring structure while pyrimidines only have a single ring.

What are the four nitrogen bases of DNA?

Attached to each sugar is one of four bases–adenine (A), cytosine (C), guanine (G), or thymine (T). The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.

How do you know if RNA is single or double stranded?

The presence of Uracil shows that it is RNA. The base composition is unequal, so it must be single stranded. A has a higher melting temperature. The triple hydrogen bonds between G and C are harder to break, so fragments with higher GC content will have a higher melting temperature.

Does double stranded RNA exist?

Double-stranded DNA and RNA, and DNA/RNA hybrids form naturally in cells between two nucleic acid strands containing complementary sequences. However, these double-stranded nucleic acid structures need to be separated for DNA replication, RNA transcription, RNA processing, and DNA repair.

What will happen if double stranded RNA is produced during transcription?

Second, the two RNA molecules if produced simultaneously would be complementary to each other. Hence would form a double stranded RNA. This would prevent RNA from being translated into protein and the exercise of transcription would become a fertile one.

What is the difference between single and double stranded DNA?

The DNA molecules are not always double stranded helical structures, sometimes they occur in single stranded form called ssDNA….ssDNA vs dsDNA – A Comparison Table.

Sl. No. dsDNA ssDNA
1 Double stranded DNA is linear or filamentous form Single stranded DNA is usually stellate or star shaped

Does single stranded DNA have a secondary structure?

Single-stranded DNA (ssDNA) viruses have genomes that are potentially capable of forming complex secondary structures through Watson-Crick base pairing between their constituent nucleotides.

Why are DNA double stranded?

The common theme of all the excision mechanisms is that DNA must be double stranded to provide a template for the repair. Separate from these, there are proteins involved in the direct reversal of damage (e.g., photoreactivation, O6 methylguanine DNA methyl transferase).

What does a positive double stranded DNA mean?

The anti-double stranded DNA (anti-dsDNA) test is used to help diagnose lupus (systemic lupus erythematosus, SLE) in a person who has a positive result on a test for antinuclear antibody (ANA) and has clinical signs and symptoms that suggest lupus.

What cancers are associated with positive ANA?

Neoplastic diseases may cause positive ANA. Some authors have described that ANA is found in the sera from lung, breast, head and neck cancer patients as frequently as in RA and SLE 3, 4, 5. Chapman et al. 6 has suggested that in breast cancer they may be used as an aid to early diagnosis.

What is normal anti DNA double-stranded?

<30.0 IU/mL Negative 30.0 – 75.0 IU/mL Borderline >75.0 IU/mL Positive Negative is considered normal. changes in the levels of these antibodies should not be relied upon to predict changes in clinical course of patients with LE.

What does a lupus attack feel like?

About 80% of people develop joint and muscle pain, skin rashes, fatigue and a general feeling of being unwell. During a lupus flare-up the most common complaints are of flu-like symptoms (with or without fever), fatigue, muscle and joint pains.