gene expression and nucleic acids Flashcards
what is a nucleic acid?
DNA and RNA
What are the monomers of nucleic acids?
nucleotides
what are the polymers
DNA or RNA
what is the structure of DNA?
double stranded, bases A T C and G, deoxyribose sugar and phosphates
what is mRNA
takes a copy of a genetic code that encodes for a specific protein to the ribosome
what is tRNA
brings an amino acid to ribosome through a complementary anti-codon to the mRNA’s codon
what is rRNA?
ribosomal RNA, forms a ribosome along with other proteins
what is the general structure of a nucleotide?
phosphate group, deoxyribose/ribose sugar and a nitrogenous base
what is condensation polymerisation?
used to join amino acids by creating a peptide bond through the creation of a water molecule from a hydroxyl group on the 3’ end and a hydrogen from the 5’ end of another amino acid
what is the anti parallel nature of DNA?
one strand runs 5’ - 3’ with the 5’ carbon pointing up while the other runs 3’ - 5’ with the 5’ carbon pointing downwards (opposite directions)
what does it mean why the genetic code is universal?
all organisms contain the same 4 bases that make up DNA, meaning all amino acids are coded for by the same codons in all organisms
what does it mean by the genetic code is degenerate
a single amino acid can be coded for by more than one codon
what are the steps of transcription or translation?
initiation, elongation and termination
what does initiation do in transcription?
RNA polymerase (transcription factor) binds to the promoter region and unwinds and unzips the DNA, breaking the hydrogen bonds and exposing nitrogenous bases
what does elongation do in transcription?
free nucleotides are added in a 5’ to 3’ direction as the RNA polymerase moves along (DNA recoils after polymerase has passed)
what is termination in transcription?
where transcription ends when RNA polymerase reaches the termination site (stop triplet), chemicals are released causing polymerase to detach
what are the three steps of RNA processing?
methyl cap, poly-a-tail and splicing
what is a methyl cap?
added to 5’ end of pre-mRNA
what is a poly-a-tail?
added to the 3’ end of the pre-mRNA molecule, increases stability and prevents degrading
what is splicing?
a spliceosome removes introns and joins exons together
what is alternative splicing?
the removal of different exons to give arise to different proteins
what is initiation in translation?
ribosome attaches to the 5’ end of mature mRNA and moves along until it reaches the AUG start codon when the corresponding tRNA will bring the amino acid met
what is elongation in translation?
the ribosome continues reading and the tRNA bring corresponding amino acids, they join the growing polypeptide chain via condensation polymerisation
what is termination in translation?
the ribosome reaches a stop codon where it detaches
