Molecular Biology and Genetics

The claim that DNA sequence is the only factor dictating gene expression is fiction. Epigenetic modifications (such as DNA methylation and histone acetylation) and environmental factors play a massive role in regulating how and when genes are expressed without altering the underlying DNA sequence.

During transcription, RNA nucleotides pair with the template DNA strand. Uracil (U) in RNA pairs with Adenine (A) in DNA, while Adenine (A) in RNA pairs with Thymine (T) in DNA.

RNA is typically single-stranded, whereas DNA is double-stranded. RNA does contain ribose sugar, uracil instead of thymine, and a phosphate group.

The biological nitrogen fixation reaction catalyzed by the nitrogenase enzyme is energetically expensive. It requires the hydrolysis of at least 16 ATP molecules to reduce one molecule of nitrogen gas into two molecules of ammonia.

The structure of DNA is a double helix, consisting of two strands of nucleotides coiled around each other. This was famously described by Watson and Crick.

DNA is an abbreviation for Deoxyribonucleic Acid, which is the molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known organisms.

DNA consists of a sugar-phosphate backbone, where the sugar is deoxyribose and the phosphate groups link the nucleotides together.

Hydrogen bonds form between the complementary nitrogenous bases of the two DNA strands, holding them together.

RNA contains ribose sugar, not deoxyribose. Deoxyribose is the sugar found in DNA.

DNA provides the genetic instructions for synthesizing proteins. The process involves transcription into RNA and translation into amino acid sequences.

The two strands of the DNA double helix are held together by hydrogen bonds between the complementary nitrogenous bases (A-T and G-C).

DNA polymerase adds nucleotides to the growing strand by forming phosphodiester bonds between the 3'-OH of the existing strand and the 5'-phosphate of the incoming nucleotide. It does not form the hydrogen bonds between base pairs; those form spontaneously based on complementarity.

According to Chargaff's rules, A=T and G=C. If Thymine is 20%, then Adenine is also 20%. The remaining 60% must be split equally between Guanine and Cytosine, so Guanine is 30%.

Genomic imprinting is an epigenetic phenomenon where the expression of a gene depends on whether it was inherited from the mother or the father.

Adenine and Guanine are the two purine bases found in DNA.