QUESTION 1 A scientist working in a Drosophila lab locates a mutation that has c

Question

QUESTION 1

A scientist working in a Drosophila lab locates a mutation that has caused the hind wings to be transformed into fore wings. She determines that this is a homeotic transformation. Do you agree?

True

False

QUESTION 2

The 60 amino acid homeodomain found in homeobox proteins encodes:___________ .

A. A zinc-finger.

B. An ATP-binding domain.

C. A protease.

D. A helix-turn-helix motif.

E. A leucine zipper.

QUESTION 3

Genes with products provided by the female to the egg are called:____________ .

A. Paternal-effect genes.

B. Maternal-effect genes.

C. Embryo-specific genes.

D. Egg-specific genes.

E. Sex-linked genes.

QUESTION 4

The pre-mRNAs for Sex-lethal, transformer and doublesex are:____________.

A. Longer in males.

B. Identical in length in both sexes.

C. Shorter in females.

D. Longer in females.

E. Shorter in males.

QUESTION 5

A mutation that inactivates the sex-lethal protein in fruit flies would cause:____________.

A. A fly with no ventral side.

B. Genetically male flies to develop a female phenotype.

C. A fly with two heads.

D. A fly with no dorsal side.

E. Genetically female flies to develop a male phenotype.        

QUESTION 6

Name the gene product that induces development of the apical epidermal ridge (AER) in vertebrate limb buds.

A. Giant

B. Sonic Hedgehog

C. Fibroblast growth factor

D. Cactus

E. Nanos

QUESTION 7

mRNA transcripts for Hox genes are expressed at uniform levels throughout the fruit fly embryo, but are only translated into protein in the segments they regulate.

True

False

QUESTION 8

The maternal-effect Bicoid gene codes for:_____________ .

A. A signal protein.

B. A DNA-binding transcription factor.

C. A cell-to-cell junction protein

D. A transmembrane protein.

E. A serine protease.

QUESTION 9

In Drosophila melanogaster, Hox genes are:___________________ .

A. Clustered together in two gene complexes.

B. Evenly distributed throughout the genome.

C. Clustered in one large gene complex.

D. Clustered together in three gene complexes.

E. Clustered into operons.

QUESTION 10

The class of genes required for establishing the anteroposterior axis is:____________ .

A. The maternal-effect genes.

B. The gap genes.

C. The segment polarity genes.

D. The hox genes.

E. The pair-rule genes.

Explanation / Answer

1. A mutation resulting in hind wings transformed into forewings is due to homeotic transformations. Hence, the given statement is true. Homeotic transormation result in wrong body parts in wrong locations.

2. The homeo domain is 60 amino acid length sequence and the domain binds DNA through helix - turn - helix motif. Option D is correct.

3. Maternal effect genes are the genes that provide products by females to eggs. Hence, option B is correct. The genes providing products sperms or male gametes are called paternal genes.

4. The pre-mRNAs for Sex-lethal, transformer and double sex (loss of function mutations) are longer in females than in males due to unspliced introns occurring in the pre-mRNA. Option D is correct. In males these genes undergo alternative splicing and hence, introns are removed.

5. In Drosophila mutation inactivating the sex lethal protein results in genetically female fly developing into a male fly. Option E is correct. This is because the sex lethal protein encoded by Sxl gene inactivated by trans gene encoded mutated protein that may result in formation of XY genotype.

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