OCR (A) Biology A-level: Nucleotides and Nucleic Acids

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Questions and Answers

Explain the concept of semi-conservative replication of DNA.

Semi-conservative replication of DNA ensures that each new DNA molecule contains one original strand and one newly synthesized strand. This allows for the genetic information to be passed on from one generation of cells to the next.

Explain the difference between exons and introns in the genome.

Exons are the coding regions of the genome that are translated into proteins, while introns are the non-coding regions that are not translated into proteins.

Describe the features of the genetic code that make it efficient and adaptable.

The genetic code is non-overlapping, meaning each triplet is read only once, and it is also degenerate, meaning multiple codons can code for the same amino acid. These features reduce the phenotypic effects of mutations and make the genetic code more adaptable.

What is the role of the genetic code in protein synthesis?

The genetic code consists of triplets of bases, known as codons, where each codon codes for a specific amino acid. This allows the sequence of amino acids in a polypeptide chain to be determined by the sequence of bases in the DNA. Signup and view all the answers

Explain the two main stages of protein synthesis and the differences between them.

Protein synthesis consists of two main stages: transcription and translation. Transcription occurs in the nucleus and involves the synthesis of mRNA from a DNA template, while translation occurs in the cytoplasm and involves the synthesis of a polypeptide chain using the mRNA as a template. Signup and view all the answers

How can mutations in the DNA sequence lead to changes in the protein structure and function?

Mutations in the DNA sequence can alter the amino acid sequence of the resulting protein, which can lead to changes in the protein's structure and function. This can have various effects, including causing harmful conditions like cystic fibrosis or sickle cell anemia. Signup and view all the answers