chapter 7 Flashcards
the hypothesis, proposed by Beadle and Tatum, that each gene is unique and codes for the synthesis of a single enzyme
one gene- one enzyme hypothesis
the hypothesis that each gene is unique and codes for the synthesis of a single polypeptide; the restated version of the one gene-one enzyme hypothesis
one gene- one polypeptide hypothesis
the fundamental principle of molecular genetics, which states that genetic information flows from DNA to RNA to proteins
central dogma
mechanism by which the information coded in nucleic acids of DNA is copied into the nucleic acids of RNA; something rewritten in the same language
transcription
mechanism by which the information coded in the nucleic acids of RNA is copied into the amino acids of proteins
translation
the end product of the transcription of a gene; is translated by ribosomes into a protein
messenger RNA
a carrier molecule that binds to a specific amino acid and adds the amino acid to the growing polypeptide chain
transfer RNA
an RNA molecule within the ribosome that bonds the correct amino acid to the polypeptide chain
Ribosomal RNA
an enzyme that reads a DNA strand and creates a complementary strand of RNA
RNA polymerase
the DNA strand that is copied into an mRNA molecule during gene transcription
template strand
the initial RNA transcription product
precursor mRNA
the specific coding relationship between bases and the amino acids they specify; the genetic code can be expressed in terms of either DNA or RNA bases
genetic code
a group of three base pairs that code for an individual amino acid
codon
the codon that signals the start of a polypeptide chain and initiates translation
start codon
a codon that signals the end of a polypeptide chain and causes the ribosome to terminate translation
stop codon
a nucleotide sequence that lies just before a gene and allows for the binding of RNA polymerase
promoter
a region of the promoter that enables the binding of RNA polymerase
TATA box
the DNA strand that is not being copied but contains the same sequence as the new RNA molecule
coding strand
a sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing
termination sequence
a chain of adenine nucleotides that are added to the 3’ end of the pre-mRNA molecule to protect it from enzymes in the cytosol
poly(A) tail
a sequence of seven Gs that is added to the start of a pre-mRNA molecule; ribosomes recognize this site and use it as the site of initial attachment
5’ cap
a sequence of DNA or RNA that codes for part of a gene
exon
a non-coding sequence of DNA or RNA
intron
an enzyme-protein complex that removes introns from the mRNA
spliceosome
a protein that binds to introns and signals them for removal
small ribonucleoprotein (snRNP)
a process that produces different mRNAs from pre-mRNA (exons and introns), allowing more than one possible polypeptide to be made from a single gene
alternative splicing
the complementary sequence of base pairs on a tRNA that corresponds to a codon on an mRNA
anticodon
the process by which a tRNA molecule is bound to its corresponding amino acid
aminoacylation
a molecule of transfer RNA bound to its associated amino acid
aminoacyl-tRNA
a particular system for separating a base pair sequence into readable codons
reading frame
a complex that is formed when multiple ribosomes attach to the same mRNA molecule in order to facilitate rapid translation
polysome
a hormone produced in the pancreas that lowers the blood glucose level by promoting the uptake of glucose by the body cells
insulin
a cluster of genes that contains the DNA sequences to regulate the metabolism of lactose
lac operon
the region in the operon that regulatory factors bind to
operator
a protein that binds to the operator to repress gene transcription
repressor protein
a signal molecule that triggers the expression of an operon’s genes
inducer
a signal molecule that binds to a regulatory protein to reduce the expression of an operon’s genes
corepressor
a change in a single nucleotide within a gene
point mutation
the replacement of one base pair in a DNA sequence by another base pair
substitution
the addition of a base pair (small-scale mutation) or larger coding region (large-scale mutation) to a DNA sequence
insertion
the removal of a base pair (small-scale mutation) or larger coding region (large-scale mutation) from a DNA sequence
deletion
two adjacent bases trading places (small-scale mutation) or the reversal of a sequence of DNA (large-scale mutation)
inversion
a difference in the DNA between individuals caused by point mutations
single nucleotide polymorphism (SNP)
a mutation that changes a single amino acid in the coding sequence
missense mutation
a mutation that results in a premature stop codon
nonsense mutation
a mutation that does not alter the resulting sequence of amino acids
silent mutation
a shift in the reading frame resulting in multiple missense and/or nonsense effects
frameshift mutation
the movement of entire genes or sequences of DNA from one chromosome to another
translocation
a mutation that is caused by an error in DNA replication
spontaneous mutation
a mutation that is caused by an environmental agent
induced mutation
an environmental agent that directly alters the DNA within a cell
mutagen
