1.3 Nucleotides Flashcards
What is a nucleotide
Molecules that contain a pentose sugar, a nitrogen base and a phosphate group
What is a nucleic acid
The polymer of a nucleotide
What is ATP made up of
Adenine, a ribose sugar and 3 phosphates
Which bases are pyrimidines and which are purines
Pyrimidines = C, U, T
Purines = G and A
What is non-overlapping code
When each base only joins one codon which synthesises 1 amino acid
What is a degenerate code
That some amino acids can be coded by one or more codon
What is universal code
Code is the same in the cells of most living things
What is a deletion mutation
When a nucleotide is deleted causing a frame shift
What is an insertion mutation
When a nucleotide is added causing a frame shift
What is a substitution mutation
When a nucleotide is replaced by a different nucleotide
What is a frame shift
When a nucleotide is added or deleted it causes all of the codons to change causing different amino acids to be coded
What effect does a mutation have
1) Change in base sequence
2) Change in primary structure
3) Change in bonding
4) Alters proteins tertiary structure
What are the 3 DNA Enzymes
DNA Helicase
DNA Ligase
DNA Polymerase
What does DNA Helicase do
Unzips the 2 strands of DNA
What doe DNA Ligase do
Catalyses the formation of phosphodiester bonds between the 2 strands of DNA
What does DNA polymerase do
LInes up + catalyses the the linking of nucleotides along the template strand
What happens in transcription
1) DNA helicase moves along the DNA unwinding the strand, breaking the H bonds
2) RNA nucleotides are added to their complementary bases
3) The mRNA detaches from the DNA + the double helix reforms
4) The mRNA leaves the nucleus + travels to the ribosome
What happens in translation
1) The complementary anticodon of a tRNA is attached to the 1st codon of the mRNA + H bonds are formed
2) The 2nd codon also attaches to its complementary anticodon
3) A peptide bond forms between the 2 amino acids
4) The 1st tRNA leaves the ribosome
5) The ribosome moves along to the 3rd codon
6) Process is repeated to form a polypeptide chain and until the ribosome reaches a stop codon
Similarities between DNA and RNA
1) Both have a sugar, nitrogenous base and a phosphate group
2) Both contain C,A and G as bases
3) Both use H bonds for complementary base pairing
4) Nucleotides are linked together by phosphodiester bonds
Differences between DNA and RNA
1) DNA is double stranded, RNA is single stranded
2) DNA has a deoxyribose sugar, RNA has a ribose sugar
3) DNA has base T, RNA has base U
4) DNA stores genetic information, RNA is used for protein synthesis
