Chapter 17

Question 1

Gene expression

Answer 1

process by which DNA directs the synthesis of proteins or RNA

Question 2

Beadle and Tatum hypothesis

Answer 2

one-gene-one polypeptide hypothesis, states that the function of a gene is to dictate the production of a specific enzyme

Question 3

Transcription

Answer 3

synthesis of RNA using in information in the DNA, DNA->RNA,

Question 4

messenger RNA

Answer 4

carries a genetic message from the DNA to the protein synthesizing machinery of the cell

Question 5

Translation

Answer 5

synthesis of a polypeptide using the information in the mRNA, RNA->Protein, uses ribosomes

Question 6

ribosomes

Answer 6

site of translation, molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains

Question 7

primary transcript

Answer 7

initial RNA transcript from any gene

Question 8

triplet code

Answer 8

genetic instructions for a polypeptide chain written in the DNA as a series of nonoverlapping, three nucleotide words in mRNA

Question 9

template strand

Answer 9

the strand of DNA that provides the pattern, or template, for the sequence of nucleotides in an RNA transcript

Question 10

codons

Answer 10

the mRNA nucleotide triplets written in the 5 prime to the 3 prime direction

Question 11

coding strand

Answer 11

nontemplate DNA strand, used when a gene’s sequences is reported

Question 12

RNA polymerase

Answer 12

pries the two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand which elongates the RNA polynucleotide

Question 13

promoter

Answer 13

DNA sequence where RNA polymerase attaches and initiates transcription

Question 14

terminator

Answer 14

in bacteria, the sequence that signals the end of transcription

Question 15

transcription unit

Answer 15

the stretch of DNA downstream from the promoter that is transcribed into an RNA molecule

Question 16

transcription factors

Answer 16

in eukaryotes, mediates the binding of RNA polymerase and the initiation of transcription

Question 17

transcription initiation complex

Answer 17

where the whole complex of transcription factors and RNA polymerase II are bound to

Question 18

TATA box

Answer 18

a promoter crucial in forming the initiation complex

Question 19

RNA processing

Answer 19

both ends of the primary transcript are altered

Question 20

5 prime cap

Answer 20

a modified form of a guanine nucleotide

Question 21

poly A tail

Answer 21

the “3 prime cap”, modified preMRNA, modified adenine

Question 22

what do 5 prime cap and poly A tail do

Answer 22

facilitate the export of the mature mRNA from the nucleus

Question 23

RNA splicing

Answer 23

large portions of the RNA molecules are removed and the remaining portions are reconnected

Question 24

introns

Answer 24

noncoding segments of nucleic acid that lie between coding regions called intervening sequences, they go OUT

Question 25

exons

Answer 25

regions that are translated into amino acid sequences, go IN

Question 26

Ribozymes

Answer 26

RNA molecules that function as enzymes

Question 27

spliceosome

Answer 27

large complex made of proteins and small RNAs that removes introns

Question 28

alternative RNA splicing

Answer 28

genes that can give rise to two or more different polypeptides depending on which segments are used as exons

Question 29

transfer RNA

Answer 29

RNA that transfers amino acids to the growing polypeptide in a ribosome, can translate an mRNA codon into a given amino acid

Question 30

anticodon

Answer 30

the particular nucleotide triplet that base pairs to a specific mRNA codon

Question 31

aminoacyl-tRNA synthetase

Answer 31

the enzyme that finds the correct match between a tRNA and an amino acid

Question 32

ribosomal RNA

Answer 32

RNA made of ribosomes

Question 33

3 stages of translation

Answer 33

ribosome association and initiation of translation, elongation of the polypeptide chain, termination of translation

Question 34

P site

Answer 34

holds the tRNA carrying the growing polypeptide chain

Question 35

A site

Answer 35

holds the tRNA carrying the next amino acid to be added to the chain

Question 36

E site

Answer 36

discharged tRNAs leave the ribosome, eject site

Question 37

signal peptide

Answer 37

targets the protein the the ER

Question 38

signal recognition particle

Answer 38

recognizes the signal peptide as it emerges from the ribosomes

Question 39

poly ribosomes or polysomes

Answer 39

enable a cell to rapidly make many copies of a polypeptide

Question 40

mutations

Answer 40

changes to genetic information of a cell

Question 41

point mutations

Answer 41

changes in a single nucleotide pair of a gene

Question 42

nucleotide-pair substitutions

Answer 42

replacement of one nucleotide and its partner with another pair of nucleotides

Question 43

silent mutations

Answer 43

mutation that has no observable effect on the phenotype

Question 44

missense mutations

Answer 44

substitutions that change one amino acid to another

Question 45

nonsense mutation

Answer 45

when a codon for an amino acid is changed into a stop codon, lead to nonfunctional proteins

Question 46

insertions and deletions

Answer 46

have disastrous effects on the resulting protein more often that substitutions

Question 47

frameshift mutation

Answer 47

occurs whenever the number of nucleotides inserted or deleted is not a multiple of three

Question 48

mutagens

Answer 48

agents that interact with DNA in a way that causes mutations