coding for proteins Flashcards
(33 cards)
what is an exon?
a base sequence in a gene that codes for the sequence of amino acids
what is an intron?
a base sequence in a gene that is non-coding
what 3 ways can we describe the genetic code?
non-overlapping
degenerate
universal
what does non-overlapping genetic code mean?
each nucleotide is part of ONLY one triplet
what does a degenerate genetic code mean?
More than one triplet codes for a single amino acid
what does a universal genetic code mean?
in nearly all organisms the same triplet codes for the same amino acid.
what is a locus?
the position of a gene on a chromosome
what is a a genome?
a complex set of genes in a cell
what is proteome?
the full range of proteins a cell can produce
what is the definition of a gene mutation?
a change in the base sequence of a chromosome (can happen during DNA replication)
what is a mutagenic agent?
they increase the rate of mutations.
what is a base deletion mutation?
a nucleotide is removed from DNA sequence causing a change to the sequence of triplets which changes the sequence of amino acids (primary structure)
what is a base substitution mutation?
when a base is swapped for a different one. it can either result in a different amino acid or the same one as the genetic code is degenerate. therefore, there is a smaller chance of a mutation.
what does RNA contain?
a base, a pentose sugar (ribose) and a phosphate group
what bases does RNA contain?
adenine, uracil, cytosine and guanine
What joins RNA and DNA nucleotides?
a condensation reaction forming phosphodiesther bonds
what is the role of RNA?
to take DNA information from the nucleus to the ribosomes
what does mRNA stand for?
messenger ribose nucleic acid
what is the structure of mRNA and what is the role of it?
a single stranded helix (often presented as a single straight strand). it is responsible for carrying info from the DNA to the ribosomes for translation
what is the process of transcription?
hydrogen bonds in-between bases are broken by RNA POLYMERASE leaving exposed DNA strands. RNA nucleotides move in and attach to complementary bases on 1 template DNA strand. the attach using a condensation reaction forming a phosphodiester bond. resulting in a strand of pre mRNA and the DNA double helix.
what is a gene?
a base sequence of DNA that codes for the amino acid sequence of a polypeptide
does pre mRNA contain introns, exons or both?
both in PRE mRNA
what is splicing?
splicing remove the introns and leaves only the exons creating mRNA
does splicing occur in prokaryotes?
no, in prokaryotes there are no introns so no splicing is needed
