DNA Structure and Function Concepts

The video tutorial covers the AQA A-level biology topic of DNA, genes, and chromosomes. It begins with an overview of the differences between prokaryotic and eukaryotic DNA, highlighting that prokaryotic DNA is short, circular, and not associated with proteins, while eukaryotic DNA is long, linear, and associated with histones. The tutorial then delves into genes, explaining that they code for polypeptides or functional RNA, and discusses the genetic code's universality, non-overlapping nature, and degeneracy. It also covers non-coding DNA, including introns and multiple repeats, and concludes with a summary of the key points.

What is a key difference between prokaryotic and eukaryotic DNA?

• Eukaryotic DNA is short, circular, and not associated with proteins.

• Eukaryotic DNA is circular and not associated with proteins.

• Prokaryotic DNA is linear and associated with histones.

• Prokaryotic DNA is short, circular, and not associated with proteins.

What role do histones play in eukaryotic cells?

• They are not present in eukaryotic cells.

• They convert DNA into RNA.

• They help DNA fit into the nucleus by winding it tightly.

• They make DNA circular.

What does the endosymbiotic theory suggest about mitochondria and chloroplasts?

• They are responsible for protein synthesis.

• They do not contain any DNA.

• They are unique to prokaryotic cells.

• They evolved from free-living bacteria.

What is a gene?

• A structure that holds sister chromatids together.

• A type of RNA involved in protein synthesis.

• A protein that binds to DNA.

• A sequence of DNA that codes for a polypeptide or functional RNA.

What is the role of a triplet in a gene?

• It codes for a specific protein.

• It codes for a specific amino acid.

• It is involved in DNA replication.

• It determines the shape of DNA.

What does it mean that the genetic code is universal?

• It is unique to humans.

• It changes between different species.

• It is the same in all living organisms.

• It only applies to eukaryotic cells.

Why is the genetic code described as degenerate?

• It overlaps between different genes.

• Each amino acid is coded by multiple codons.

• Each codon codes for multiple amino acids.

• It is not used in all organisms.

What are introns?

• Proteins that bind to DNA.

• Non-coding sequences within genes.

• Sequences that code for amino acids.

• Coding sequences in genes.

What are non-coding multiple repeats?

• Repeated sequences that do not code for amino acids.

• Sequences that are involved in DNA replication.

• Sequences that code for proteins.

• Sequences that are only found in prokaryotes.

What must happen to introns before translation?

• They must be converted into exons.

• They must be translated into proteins.

• They must be duplicated.

• They must be spliced out.