Question

4) Mary has a gene for a clotting factor that contains a CUU codon. Laura’s gene has a CUG codon in the same place. However, both of their clotting factor proteins are identical. We call this a ________ mutation. This is possible because of the __________ of the genetic code. A. missense; universality B. silent; rare codon usage C. nonsense; specificity D. silent; redundancy

5) HIV can only infect macrophages and helper T cells because they have which proteins used by HIV to enter the cell? A. p53 and CC55 B. ras and gp120 C. cytokine; neuraminidase D. CD4 and CCR5

6) Gardasil is a vaccine against _______ which is known to cause cervical cancer. A. HIV B. HPV C. EBV D. polio

Answer 1

4.

Mary has a gene for a clotting factor that contains CUU codon. Laura's gene has a CUG codon in the same place . However both of their clotting factor proteins are identical. We call this a Silent mutation. This is possible because of the Redundancy of the genetic code.

Silent mutations are neutral mutations that donot result in change in aminoacid sequence of a protein. Here both CUU and CUG code for the same aminoacid, Leucine.So there is no change in aminoacid sequence or any phenotypic change. The phenomenon of single aminoaid coded by many codons is called redundancy of genetic code. Here Leucine is coded by CUU and CUG.

Other options are wrong. Missense mutations are those cause change in aminoacids. Nonsense mutation is the mutation by introduction of stop codon. These two mutations are not seen in the above example. Universality of genetic codon is not reason for silent mutation here.

Option D is the answer.

SILENT; REDUNDANCY.

5.

HIV can only infect macrophages and helper T cells because they have proteins, CD4 AND CCR5.

CD4 is a glycoprotein found on the surface of helper T cells and macrophages. this protein is used by the HIV virus for the spread of infection.

* CD4 serves as a high affinity protein receptor for HIV .

CCR5 /CHEMOKINE RECEPTOR 5 is also used by the HIV virus to infect cells. It is the main receptor protein found on surface of macrophages. HIV utilize CCR5 as a co receptor to enter the target cells.

Other options are incorrect. P 53 is related to regulation of cell cycle. GP120 is the glycoprotein is seen on envelope of HIV virus. Neuraminidase is a enzyme that cleave glycosidic bonds. Cytokines are group of proteins secreted by immune cells. So these terms are not the answers.

Option D is the answer.

CD4 AND CCR5.

6.

Gardasil is a vaccine againt HPV.

Gardasil is vaccine which is used against Human Papillomavirus type 6 and 11. this is a non infectious  recombinant vaccine prepared from purified virus like particlesof the major capsid protein of HPV.

Gardasil is not used against HIV,polio, EBV. so other options are incorrect.

Option B is the answer.

HPV.