Unit 1.1 - DNA Structure and Organisation

• How many strands are a molecule of DNA composed of?

  Two.
• What are DNA strands made up of?


  Repeating units, called nucleotides.
• What are nucleotides made up of?

  A molecule of deoxyribose sugar joined to a phosphate group and an organic base.
• What does the sequence of bases determine?

  The organisms genotype and the structure of its proteins.
• What is the shape of deoxyribose sugar in nucleotides determined by?

  The arrangement of carbon atoms in the molecule.
• How many carbon atoms are there per Deoxyribose sugar?

  5
• What is the carbon atom 5' connected to?

  The phosphate
• What connects a nucleotides phosphate group to another nucleotides carbon 3' on the deoxyribose sugar?

  A strong chemical bond.
• What does joining the nucleotides form?

  Sugar-phosphate backbone
• What carbon does the base attach to?

  Carbon 1
• What are the 2 strands of nucleotides joined by?

  Weak hydrogen bonds.
• What is the base pairing rule?

  Adenine pairs with Thymine.

  Guanine pairs with Cytosine.
• What is the shape of DNA?

  Double stranded helix
• What does it mean when we say DNA is made up of 2 antiparallel strands?

  The strands run in opposite directions of each other.
• What are the 2 cell groups called?

  Eukaryotes and Prokaryotes.
• What type of cell is a bacteria cell?

  Prokaryotes.
• What features do prokaryotes have?

  No nucleus and their DNA is in a cytoplasm.
• How do bacteria cells store DNA?

  A single, circular chromosome and smaller circular plasmids.
• What features do eukaryotic cells have?

  All have linear chromosomes in the nucleus. All contain circular chromosomes in their mitochondria and chloroplasts.
• Explain Linear chromosomes

  They are tightly coiled and packaged with associated proteins called histones.
• Why are yeast cells different?

  They are a type of eukaryotic cell but contain plasmids.