1.5.1 Structure Of DNA And RNA Flashcards
Describe the basic function of DNA in all living cells
DNA - Holds genetic information which codes for polypeptides (proteins)
Describe the basic function of RNA in all living cells
RNA Transfers genetic information from DNA to ribosomes
Name the two types of molecule from which a ribosome is made
RNA and proteins
Draw and label a DNA nucleotide
Draw and label a RNA nucleotide
Describe the differences between a DNA nucleotide and an RNA nucleotide
DNA nucleotide - Pentose sugar is deoxyribose , base can be thymine
RNA nucleotide - Pentose sugar is ribose, base can be uracil
Describe how nucleotides join together to form polynucleotides
● Condensation reactions, removing water molecules
● Between phosphate group of one nucleotide and deoxyribose / ribose of another
● Forming phosphodiester bonds
Why did many scientists initially doubt that DNA carried the genetic code?
The relative simplicity of DNA - chemically simple molecule with few components
Describe the structure of DNA
● Polymer of nucleotides (polynucleotide)
● Each nucleotide formed from
deoxyribose, a phosphate group and a
nitrogen-containing organic base
● Phosphodiester bonds join adjacent
nucleotides
● 2 polynucleotide chains held together by
hydrogen bonds
● Between specific complementary base
pairs - adenine / thymine and cytosine / guanine
● Double helix
Describe the structure of (messenger) RNA
● Polymer of nucleotides (polynucleotide)
● Each nucleotide formed from ribose, a phosphate
group and a nitrogen-containing organic base
● Bases - uracil, adenine, cytosine, guanine
● Phosphodiester bonds join adjacent nucleotides
● Single helix
Compare and contrast the structure of DNA and (messenger) RNA
DNAs Pentose sugar is deoxyribose whereas RNAs Pentose sugar is ribose
DNA has has the base thymine whereas RNA has the base uracil
DNA is double stranded / double helix whereas RNA is single stranded / single helix
DNA is long (many nucleotides) whereas RNA is shorter (fewer nucleotides)
DNA has hydrogen bonds / base pairing whereas RNA does not
Suggest how the structure of DNA relates to its functions
● Two strands → both can act as templates for semi-conservative replication
● Hydrogen bonds between bases are weak → strands can be separated for replication
● Complementary base pairing → accurate replication
● Many hydrogen bonds between bases → stable / strong molecule
● Double helix with sugar phosphate backbone → protects bases / hydrogen bonds
● Long molecule → store lots of genetic information (that codes for polypeptides)
● Double helix (coiled) → compact
Suggest how you can use incomplete information about the frequency of bases on DNA strands to find the frequency of other bases
- % of adenine in strand 1 = % of thymine in strand 2 (and vice versa)
- % of guanine in strand 1 = % of cytosine in strand 2 (and vice versa)
Because of specific complementary base pairing between 2 strands
