AQA A level Biology Specificaton
Unit 3.4 Genetic information, variation and relationships between organisms
Topic: DNA Genes and Chromosomes
Power Point and complementary worksheet
This lesson covers:
Can you explain that, in prokaryotic cells, DNA molecules are short, circular, and not associated with proteins?
Can you explain that, in the nucleus of eukaryotic cells, DNA molecules are very long, linear and associated with proteins, called histones?
Can you describe how a DNA molecule and its associated proteins form a chromosome?
Can you explain that the mitochondria and chloroplasts of eukaryotic cells also contain DNA which, like the DNA of prokaryotes, is short, circular and not associated with protein?
Can you explain how a gene is a base sequence of DNA that codes for the amino acid sequence of a polypeptide and a functional RNA (including ribosomal RNA and tRNAs)?
Can you describe how a gene occupies a fixed position, called a locus, on a particular DNA molecule?
Can you explain how a sequence of three DNA bases, called a triplet, codes for a specific amino acid?
Can you explain that the genetic code is universal, non-overlapping, and degenerate?
Can you explain that in eukaryotes, much of the nuclear DNA does not code for polypeptides?
Can you explain that, even within a gene only some sequences, called exons, code for amino acid sequences?
Can you explain that, within the gene, these exons are separated by one or more non-coding sequences, called introns?