Question

Page 2 of 8 12. What type of mutationales the base, but not the amino acid being coded for? mutations? point nonsense 12. framstiftis caused by m ense and insertion misense and nonsense Dansene and deletion 2 doletion and insertion insertion and nonsense 14. A mutation that changes a normal codon to a stop codon is called a #paint mutation silent mutation & back mutation 2 misserse mutation & nonsense mutation 15. Repreble operons require that_ bind to the repressor protein before it can bind to the operator. the product 2 acilactor ecoenzyme & the substrate the rectant 16. Gene regulation can involve a protein repressor that blods_ DNA polymerase I from initiating transcription. DNA polymerase III G RNA polymerase Coenzyme A 17. Hilinduction of the lactose operon requires & None of the above 4 Lactose present Lactose and glucose present § Lactose present without glucose All the choices induce the lactose operon 18 The operan segment composed of the gene that code for a protein repressor is called the 4 Operator Structural loans & None of the choices are correct 19. Which is incorrect about inducible operons! & Have genes tumed off by a buildup of end product b) Are offen for catabolic pathways Are normally tumed off d) Are tumed on by the substrate of the enzyme c) Indude the lac operon 20. sequence of buses an agene that does not code for protein is called a) Promoter b) Operator Operon d) Econ e Intron 21. Which of the following is income about codon? (see Figure 9.13) Are also called nonsense codons b) Indude AUG Indude UAA, UAG, UGA d) Do not have comesponding TRNA an (se figure 9.17)

Answer 1

12 ans) a. Sillent

Explaination: Silent mutation cause changes in bases but does not alter the amino acids.

13 ans) d. deletion and insertion

Explaination: Frame shift mutation cause change in reading frame of codons by addition of new base or by deleting present bases.

14 ans) e. nonsense mutation

Explaination: In nonsense mutation single base substitution can tranform normal codon into stop codon.

15 ans) a. the product

16 ans) c. RNA polymerase

Explaination: Repressor protein blocks RNA polymerase from binding to promoter hence Transcription is inhibited.

17 ans) c. Lactose present without Glucose

Explaination: When glucose is not present lac repressor does not bind to operator hence RNA polymerase carryout transcription process and full induction of Lac operon takes place

18 ans) c. Regulator

Explaination: Operon segment is composed of regulator gene that code for protein repressor

19 ans) a. have genes turned off by a buildup of end product

Explaination: Inducible operons have genes turned off by a buildup of end product

20 ans) e. Intron

Explaination: Introns doesnot code for protein whereas exons code for proteins.

21 ans) a. Are also called nonsense codons

Explaination: Codons have only three nonsense codons also called stop codons such as UAA, UAG, UGA

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