DNA and Protein synthesis Flashcards
what is a genome
the complete set of genes present in a cell
what is the proteome
the full range of proteins that a cell is able to produce
why is the proteome usually larger than the genome
large amount of post translation modification of proteins done in the golgi
thus more different proteins can be made from the set genome (amount of genes)
splicing also allows for a gene to produce multiple different proteins
what type of molecule is RNA
polynucleotide
differences between DNA and RNA
no thymine
ribose sugar
only one polynucleotide strand
mRNA structure
sugar phosphate backbone and exposed unpaired bases
tRNA structure
single stranded with sugar phosphate backbone
folded shape (clover)
caused by hydrogen bonds
amino acids bind to specific part of molecule (on one of the “leaves” of the clover)
specific anticodon on tRNA is complementary to a specific codon on mRNA
overview of the two stages of protein synthesis
Transcription - DNA is transcribed to produce an mRNA
Translation - mRNA is translated and an amino acid sequence is produced
where does transcription occur
nucleus
process of transcription
part of a DNA molecule unwinds (helicase breaks hydrogen bonds between complementary bases)
exposes the gene
a complementary copy of this exposed gene is made by building single stranded mRNA :
Free floating RNA nucleotides pair up with unzipped DNA
RNA polymerase bonds the complementary bases together
when the gene is transcribed the hydrogen bonds between mRNA and DNA break and the double stranded DNA molecule reforms
mRNA leaves nucleus
what is the strand called that the mRNA pairs up with
template strand or transcribed strand
what is the strand called that is not transcribed
non template strand
where can non coding genes be found
between genes as non coding repeats
in genes as introns
how is premRNA made
during transcription - it contains all the introns and exons of a certain gene
what occurs before premRNA leaves the nucleus
splicing:
non coding sections removed
coding sections are joined together
resu;ting mRNA has just coding (exons) in the gene
mRNA has only exons and exits nucleus like this.
what is alternative splicing
exons of genes can be spliced in many ways to produce different mRAN molecules
reason why the genome is smaller than the proteome
process oftranslation
wheredoestranslationoccur
inthecytoplasm(inribosomes)
tRNA formation then the process of translation
in the cytoplasm tRNA are binded with there specific amino acids
the triplet of bases on the tRNA binds to specific amino acids and brings them to the ribosome
the abticodon on tRNA binds to the complementary codon on mRNA
2 tRNA molecules fit onto the ribosome at one time bringing the amino acids they carry with them
peptide bonds form between the amino acids (this process requires ATP)
process continues untill a stop codon
what do tRNA have on them
a triplet of unpaired bases at one end and a space where a specific amino acid can attach
what is required to form a peptide bond between newly created proteins
ATP
triplet definition
a sequence of 3 bases which codes for a specific amino acid
codon definition
sequence of three mRNA bases that codes for a specific amino acid
anticodon definition
sequence of three tRNA bases that are complementary to a codon
how mamy different codons can be formes
64
how many amino acids are there
20
degenerate code definition
multiple mRNA codons can encode the same amino acid
advantage of degenerate code
more resistant to mutations as a change in the genetic code does not neccesarily mean the amino acid will change
why is genetic code non overlapping
each base is only read once in the codon that it is in
