Genetic Code and DNA Concepts

This video tutorial covers the DNA, genes, and chromosomes section for AQA A Level Biology. It explains the differences between prokaryotic and eukaryotic DNA, the structure and function of genes, and the genetic code. The video also discusses the properties of the genetic code, such as its universality and degeneracy. An example exam question is provided to reinforce learning.

What is a key difference between prokaryotic and eukaryotic DNA?

• Eukaryotic DNA is short and circular.

• Prokaryotic DNA is circular and not associated with proteins.

• Eukaryotic DNA is circular and not associated with proteins.

• Prokaryotic DNA is linear and associated with histones.

Which base in RNA replaces thymine found in DNA?

• Cytosine

• Guanine

• Adenine

• Uracil

What is the role of a gene in DNA?

• It codes for the sequence of amino acids in a polypeptide.

• It is responsible for DNA replication.

• It determines the shape of the DNA molecule.

• It encodes the entire genetic code.

How many DNA bases form a codon?

• Four

• Three

• Two

• One

What amino acid does the codon 'CAG' encode?

• Serine

• Proline

• Glutamine

• Alanine

What does it mean when the genetic code is described as 'universal'?

• It varies between different species.

• It is the same for all organisms.

• It changes depending on the organism.

• It only applies to eukaryotic cells.

What is meant by the 'degenerate' nature of the genetic code?

• Multiple codons can code for the same amino acid.

• Each codon codes for multiple amino acids.

• Each amino acid is coded by a single codon.

• The genetic code is different in each organism.

What percentage of human DNA is coding for amino acids?

• About 50%

• About 10%

• About 2%

• About 25%

What are the non-coding parts of DNA called?

• Exons

• Introns

• Genes

• Codons

In the context of DNA, what is an anticodon?

• A sequence that is identical to a codon.

• A sequence that is complementary to a codon.

• A sequence that encodes a stop signal.

• A sequence that initiates DNA replication.