Biochemistry of nucleic acids, gene regulation and proteins Flashcards
what is the structure of a nucleoside?
base and 5 carbon sugar
what is the structure of a nucleotide?
nucleoside + phosphate group
what is the structure of purines?
adenine and guanine (double ring)
what is the structure of pyrimidines?
cytosine, thymine, uracil (longest name = shortest structure)
what are phosphodiesterase bonds?
form between 3’ OH group and 5’ triphosphatase - link nucleotides
what are the 4 bases in DNA molecules?
ACGT
what are the 4 bases in RNA molecules?
ACGU
what is the nomenclature for adenine?
adenosine
what is the nomenclature for cytosine?
cytidine
what is nomenclature for guanine?
guanosine
what is the nomenclature for thymine?
thymidine
where are nucleotides added to?
the free 3’ end
what must strands be in order for nuclotides to be added?
anti-parallel
what is formed between a 3’ OH and a 5’ triphosphate?
a phosphidiesterase bond
what are the base pairs inside DNA structure held together by?
hydrogen bonds
what is DNA replication catalysed by?
DNA polymerase
what does DNA replication require to start replication?
RNA primer
what are the 3 types of RNA?
rRNA, tRNA and mRNA
what is the role of tRNA?
combines with proteins to form ribosomes
what is the role of tRNA?
carries amino acids to be incorporated into protein
what is the role of mRNA?
carries genetic information for protein synthesis
what can be created is wrong nucleotides are incorporated?
mutations
DNA polymerase has 3’ -> 5’ what activity?
exonuclease
what does exonuclease activity do?
removes incorrect nucleotide
what are RNA polymerases?
multi-subunit complexes which make RNA
what are the 3 types of RNA polymerases that eukaryotes have?
Pol I, Pol II and Pol III
what Pol synthesizes mRNA?
Pol II
what do RNA polymerases do?
bind promoters for transcription to begin
what is initiation in transcription?
selection of first nucleotide of growing RNA
what is elongation in transcription?
addition of further nucleotides to RNA chain in the 5’ -> 3’ direction
what is termination in transcription?
release of finished mRNA
what are 3 steps to going from premature -> mature RNA?
splice out introns (non-coding regions)
add poly-adenosine tail
add 5’ cap
what are 4 steps of translation?
initiation
elongation
peptide bond formation and translocation
termination
what are 4 examples of post-translational modifications?
glycosylation
disulphide bonds
folding/assembly of multi-subunit proteins
specific proteolytic cleavage
what are the 3 tRNA binding sites?
peptidyl site
acceptor site
exit site
what are point mutations?
change in single base in DNA
what are missense mutations?
results in change of amino acid sequence
what are nonsense mutations?
creates new termination codon
what are silent mutations?
no change of amino acid sequence
what are frameshift mutations?
addition or deletion of 1 or 2 bases which changes the reading frame of translation
