Biology Topic 4: DNA, RNA and protein synthesis

• Describe the structure of a eukaryotic chromosome?

  Eukaryotic chromosomes are thread-like structures made up of a long molecule of DNA wound around proteins called histones. The DNA and proteins are then coiled up to form a chromosome.
• Describe how DNA in prokaryotic chromosomes differs from DNA in eukaryotic chromosomes?

  DNA in prokaryotic chromosomes is shorter than DNA in eukaryotic chromosomes, and is also circular rather than linear. Also, the DNA isn't wound around histone proteins.
• Describe 2 differences between the DNA in prokaryotic cells and the DNA in eukaryotic cells?

  Prokaryotes have short DNA/eukaryotic DNA is long

  Prokaryotes have one molecule of DNA/ eukaryotes have multiple

  Prokaryotic DNA is not associated with any proteins/ eukaryotic is (histones)

  Prokaryotic DNA does not have non-coding DNA/ eukaryotic DNA has introns (non-coding DNA within genes) and non-coding multiple repeats between genes
• A nucleotide contains a pentose sugar, phosphate group and nitrogenous base. The backbone of the DNA molecules contains the pentose sugar and phosphate group bonded together - the sugar-phosphate backbone
• A gene could code for the amino acid sequence of a polypeptide or a functional RNA product (ribosomal RNA or transfer RNA)
• The Triplet code is describes as being universal because in all organisms/DNA the same triplet codes for the same amino acid