Molecular Biology Flashcards
auxotrophs
an organism with specific nutritional requirements
crossing over
genetic material exchange between homologous chromosomes, which contributes to genetic variability; this occurs during
dominant trait
any trait expressed over another
exons
a region of a gene that is present in the final functional transcript (mRNA) from that gene Any non-intron section of the coding sequence of a gene; together the exons constitute the mRNA and are translated into protein
frameshift
a mutation in which there is an addition or deletion of one, two or a small number (not a multiple of three) of nucleotides that causes the codon reading frame to shift to one of two others from the point of the mutation during translation Consequently the amino acid sequence of the protein is altered from the point of the mutation to the terminus
intron
a noncoding, intervening sequence within a eukaryotic gene
karyotype
a cell’s chromosomal characteristics
missense substitutions
the most common type of mutation involving a base-pair substitution within a gene that changes a codon, but the new codon makes sense in that it still codes for an amino acid
nonsense substitutions
a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein
transcription
the synthesis of RNA on a DNA template
transfer RNA (tRNA)
small RNA molecules that carry amino acids to the ribosome for polymerization into a polypeptide During translation the amino acid is inserted into the growing polypeptide chain when the anticodon of the tRNA pairs with a codon on the mRNA being translated
translation
a process of protein synthesis in which the primary structure of the protein is determined by the nucleotide sequence in mRNA The ribosome-mediated production of a polypeptide whose amino acid sequence is derived from the codon sequence of an mRNA molecule
variation
any difference between members of the same species
