Chapter 14

Question 1

A modified form of guanine nucleotide added onto the end of a pre-mRNA molecule

Answer 1

5’ cap

Question 2

One of the ribosome’s three binding sites for tRNA translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain (A strands for aminoacyl tRNA)

Answer 2

A site

Question 3

A type of eukaryotic gene regulation at the RNA-processing level I’m which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns

Answer 3

Alternative RNA splicing

Question 4

An enzyme that joins each amino acid to the appropriate tRNA

Answer 4

Aminoacyl-tRNA synthease

Question 5

A nucleotide triplet at on end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule

Answer 5

Anticodon

Question 6

A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.

Answer 6

Codon

Question 7

A mutational loss of one or more nucleotide pairs from a gene.

Answer 7

Deletion

Question 8

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.)

Answer 8

E site

Question 9

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.

Answer 9

Exon

Question 10

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.

Answer 10

Frameshift mutation

Question 11

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

Answer 11

Gene expression

Question 12

A mutation involving the addition of one or more nucleotide pairs to a gene.

Answer 12

Insertion

Question 13

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.

Answer 13

Intron

Question 14

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.)

Answer 14

Messenger RNA

Question 15

A nucleotide-pair substitution that results in a codon that codes for a different amino acid.

Answer 15

Missense mutation

Question 16

A chemical or physical agent that interacts with DNA and can cause a mutation.

Answer 16

Mutagen

Question 17

A change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus.

Answer 17

Mutation

Question 18

A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

Answer 18

Nonsense mutation

Question 19

A type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides.

Answer 19

Nucleotide-pair substitution

Question 20

One of a ribosome’s three binding sites for tRNA during translation. The P site holds the tRNA carrying the growing polypeptide chain. (P stands for peptidyl tRNA.)

Answer 20

P site

Question 21

A change in a single nucleotide pair of a gene

Answer 21

Point mutation

Question 22

A sequence of 50–250 adenine nucleotides added onto the 3′ end of a pre-mRNA molecule.

Answer 22

Poly-A tail

Question 23

An initial RNA transcript from any gene; also called pre-mRNA when transcribed from a protein-coding gene.

Answer 23

Primary transcript

Question 24

A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.

Answer 24

Promoter

Question 25

On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis

Answer 25

Reading frame

Question 26

RNA molecules that, together with proteins, make up ribosomes; the most abundant type of RNA.

Answer 26

Ribosomal RNA

Question 27

A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large subunit and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. See also nucleolus

Answer 27

Ribosome

Question 28

An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing

Answer 28

Ribozyme

Question 29

An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand.

Answer 29

RNA polymerase

Question 30

Modification of RNA primary transcripts, including splicing out of introns, joining together of exons, and alteration of the 5′ and 3′ ends.

Answer 30

RNA processing

Question 31

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).

Answer 31

RNA splicing

Question 32

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.

Answer 32

Signal peptide

Question 33

A protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER

Answer 33

Signal-recognition particle (SRP)

Question 34

A nucleotide-pair substitution that has no observable effect on the phenotype; for example, within a gene, a mutation that results in a codon that codes for the same amino acid.

Answer 34

Silent mutation

Question 35

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.

Answer 35

Spliceosome

Question 36

In transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA.

Answer 36

Start point

Question 37

A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.

Answer 37

TATA box

Question 38

The DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript.

Answer 38

Template strand

Question 39

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.

Answer 39

Terminator

Question 40

The synthesis of RNA using a DNA template.

Answer 40

Transcription

Question 41

A regulatory protein that binds to DNA and affects transcription of specific genes.

Answer 41

Transcription factor

Question 42

The completed assembly of transcription factors and RNA polymerase bound to a promoter.

Answer 42

Transcription initiation complex

Question 43

A region of DNA that is transcribed into an RNA molecule

Answer 43

Transcription Unit

Question 44

An RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the tRNA recognizes the appropriate codon in the mRNA.

Answer 44

Transfer RNA

Question 45

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.

Answer 45

Translation

Question 46

A genetic information system in which a series of three-nucleotide-long words specifies a sequence of amino acids for a polypeptide chain.

Answer 46

Triplet code

Question 47

Flexibility in the base-pairing rules in which the nucleotide at the 5′ end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3′ end) of a codon.

Answer 47

Wobble