Lecture 16 Flashcards
(29 cards)
aminoacyl?tRNA synthetase
An enzyme that joins each amino acid to the appropriate tRNA.
anticodon
A nucleotide
triplet at one end of a tRNA molecule that
base-pairs with a particular complementary
codon on an mRNA molecule.
base?pair substitution
a point mutation that results in replacement of a pair of complimentary nucleotides with another nucleotide pair
codon
A three-nucleotide sequence
of DNA or mRNA that specifies a particular
amino acid or termination signal; the basic
unit of the genetic code.
deletion
1) A deficiency in a chromosome
resulting from the loss of a fragment
through breakage. (2) A mutational loss of
one or more nucleotide pairs from a gene.
exon
sequence within a primary transcript
that remains in the RNA after RNA processing;
also refers to the region of DNA from
which this sequence was transcribed.
frameshift mutation
A mutation occurring
when nucleotides are inserted in or deleted
from a gene and the number inserted or
deleted is not a multiple of three, resulting
in the improper grouping of the subsequent
nucleotides into codons.
insertion
A mutation involving the addition
of one or more nucleotide pairs to a gene.
intron
A noncoding, intervening
sequence within a primary transcript that
is removed from the transcript during RNA
processing; also refers to the region of DNA
from which this sequence was transcribed.
messenger RNA
A type of RNA,
synthesized using a DNA template, that attaches
to ribosomes in the cytoplasm and
specifies the primary structure of a protein.
(In eukaryotes, the primary RNA transcript
must undergo RNA processing to become
mRNA.)
missense mutation
A nucleotide-pair substitution
that results in a codon that codes
for a different amino acid.
mutation
A change in the
nucleotide sequence of an organism?s DNA
or in the DNA or RNA of a virus.
nonsense mutation
A mutation that
changes an amino acid codon to one of the
three stop codons, resulting in a shorter and
usually nonfunctional protein.
point mutation
A change in a single nucleotide
pair of a gene.
polyribosome
A group
of several ribosomes attached to, and translating,
the same messenger RNA molecule;
also called a polysome.
promoter
A specific nucleotide sequence in
the DNA of a gene that binds RNA polymerase,
positioning it to start transcribing
RNA at the appropriate place.
reading frame
Where the DNA genome starts and stops
ribosomal RNA
RNA molecules that, together with proteins,
make up ribosomes; the most abundant type
of RNA.
ribozymes
RNA catalysts are called ribozymes
RNA polymerase
An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand.
RNA splicing
After synthesis of a eukaryotic
primary RNA transcript, the removal
of portions of the transcript (introns) that
will not be included in the mRNA and the
joining together of the remaining portions
(exons).
signal peptide
A sequence of about 20 amino
acids at or near the leading (amino) end of
a polypeptide that targets it to the endoplasmic
reticulum or other organelles in a
eukaryotic cell.
TATA box
A DNA sequence in eukaryotic
promoters crucial in forming the transcription
initiation complex.
template strand
The DNA strand that provides
the pattern, or template, for ordering,
by complementary base pairing, the sequence
of nucleotides in an RNA transcript.
