Chapter 17 Flashcards
The process by which DNA directs the synthesis of proteins or, in some cases, just RNAs.
gene expression
The synthesis of RNA using a DNA template
transcription
A type of RNA, synthesized using a DNA template that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.
messenger RNA
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids.
translation
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in a nucleolus.
ribosomes
A set of three-nucleotide-long words that specific the amino acids for polypeptide chains.
triplet code
The DNA strand that provides the pattern, or template, for ordering the sequence of nucleotides in an RNA transcript.
template strand
An enzyme that links ribonucleotides into a growing RNA chain during transcription.
RNA polymerase
A specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
promoter
In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.
terminator
A regulatory protein that binds to DNA and affects transcription of specific genes.
transcription factors
Modification of RNA transcripts, including splicing out of introns, joining together of exons and alterations of the 5’ and 3’ ends.
RNA processing
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.
introns
A 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.
exons
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons.
spliceosome
A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced form the same primary transcript, depending on which RNA segments are treated as exons and which as introns.
alternative RNA splicing
A nucleotide triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
anticodon
Flexibility in the base-pairing rules in which the nucleotide at the 5’ end of a tRNA anticodon can from hydrogen bonds with more than one kind of base in the third position (3’ end) of a codon.
wobble
The most abundant type of RNA, which together with proteins makes up ribosomes.
ribosomal RNA
One of a ribosome’s three binding sites for tRNA during translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain. (A stands for aminoacyl tRNA)
A site
A group of several ribosomes attached to, and translating, the same messenger RNA molecule.
P site
One of a ribosome’s three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome. (E stands for exit)
E site
A group of several ribosomes attached to, and translating, the same messenger RNA molecule.
polyribosomes
A change in the nucleotide sequence of an organism’s DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus.
mutation
A change in a gene at a single nucleotide pair.
point mutation
A base-pair substitution that results in a codon that codes for a different amino acid.
missense mutation
A type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another nucleotides.
base-pair substitution
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
nonsense mutation
A mutation involving the addition of one or more nucleotide pairs to a gene.
insertion
A mutational loss of one or more nucleotide pairs from a gene.
deletion
A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
frameshift mutation
A chemical or physical agent that interacts with DNA and causes a mutation.
mutagen
Causes herpes, diabetes, and syphilis.
