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1.5 nucleic acids - Coggle Diagram
1.5 nucleic acids
lesson 2: DNA replication
DNA helicase breaks hydrogen bonds between DNA strands
DNA strands separate and unwind
both strands can now act as a template for the formation of a new strand
free DNA nucleotides in the nucleus are attracted to exposed bases on the template strands and form complementary base pairs
DNA polymerase joins adjacent nucleotides by condensation reaction forming phosphodiester bonds
called semi conservative replication as each new DNA molecule contains one new and one original strand
lesson 1: DNA and RNA structure
general structure of a nucleotide
phosphate group
nitrogenous base
pentose sugar
formation of a polynucleotide
condensation reaction between nucleotides between the pentose sugar of one nucleotide and the phosphate group of another. phosphodiester bond formed, water is lost
DNA
DNA nucleotides
phosphate group
deoxyribose
nitrogenous base (adenine, thymine, guanine, cytosine)
made of two strands of polynucleotides
strands are joined together by hydrogen bonds between complementary base pairs
adenine + thymine
guanine + cytosine
the quantities of adenine and thymine are always equal and the quantities of cytosine and guanine are always equal
RNA
RNA nucleotides
phosphate group
ribose sugar
nitrogenous base (adenine, uracil, guanine, cytosine)
single polynucleotide chain but can fold to form complementary base pairs within itself
3 different types of RNA
tRNA (transfer RNA)
brings specific amino acid to ribisome during protein synthesis
rRNA (ribisomal RNA)
ribisome made up of this RNA
mRNA (messenger RNA)
transfers genetic information from DNA to ribisomes
differences between DNA and RNA
DNA contains thymine whereas RNA contains uracil
pentose sugar is ribose in RNA whereas it is deoxyribose in
DNA
RNA one polynucleotide whereas DNA is two
DNA responsible for passing on genetic information whereas different types of RNA have different functions
DNA molecules longer than RNA molecules
lesson 3: research into DNA
initially DNA was thought to be too simple a molecule to encode out genetic information.
the work done by Rosalind Franklin, Francis Crick and James Watson to work out its structure showed it could encode information
adaptations of DNA (above spec)
the sugar phosphate backbone protects the more chemically reactive bases inside the double helix so DNA is chemically stable and rarely mutates
DNA if very large so can carry a large amount of genetic information
two strands joined by weak hydrogen bonds which allows the strands to separate for DNA replication and transcription
the bases will only pair with their complementary base, this allows DNA to maintain the genetic code during replication
