Question

1. The first gene was mapped/assigned to a specific chromosome by the laboratory of:

a.   Mendel.

b.   Thomas Morgan.

c.   Emil Krebs.

d.   Walther Flemming.

e.   Alfred Sturtevant.

2. G proteins are:
   1. examples of second messengers.
   2. found in Kreb’s cycle.
   3. parts of the photosystems in green plants.
   4. essential components of DNA replication systems.
   5. common components of signal transduction pathways.

3. A human male (has a Y chromosome) is surprisingly found to also possess a Barr body in each of his cells. This individual very likely suffers from:

1. Duchene Muscular Dystrophy.
2. Klinefelter syndrome.
3. Down syndrome.
4. Turner syndrome.
5. Huntington diseas

4. During which phase of meiosis do the centromeres uncouple and sister chromatids migrate to opposite poles of the cell?

1. anaphase I
2. prophase II
3. metaphase II
4. anaphase II
5. metaphase I

5. Which of the following are commonly associated with the “shut down” components of a signal transduction pathway:
   1. protein kinases.
   2. protein phosphatases.
   3. cAMP.
   4. Gated ion channels.
   5. caspases.

6. The enzyme that connects the short DNA fragments of the discontinuous strand at a replication form in an E. coli cell is:

1. DNA polymerase I.
2. DNA polymerase III.
3. gyrase.
4. primase.
5. DNA ligas

Answer 1

1. Correct option is B. Thomas Morgan.

Explanation - Morgan proposed that the strength of linkage between two genes depends on the distance between them on the chromosome. This became the basis for construction of maps.

2. Correct option is E. Common components of signal transduction pathways.

Explanation - G proteins are guanine nucleotide-binding proteins that act as molecular switches and are involved in transmitting signals from a variety of stimuli outside a cell to interior.

3. Correct option is B. Klinfelter's syndrome.

Explanation - XX females have one Barr body per cell whereas XXX females have 2 Barr bodies per cell. Usually, barr bodies are absent in normal XY males. But XXY Klinefelter males have one Barr body per cell.

4. Correct option is B. Anaphase ll.

Explanation - During anaphase II, the centromeres will split and sister chromatids are pulled toward the poles.

5. Correct option is E. Caspases.

Explanation - Caspases are proteases playing essential roles in programmed cell death (apoptosis) and inflammation.

6. Correct option is E. DNA ligases.

Explanation - DNA ligase can connect two strands of DNA together by forming a bond between the phosphate group of one strand and the deoxyribose group of another. It is used to join together the Okazaki fragments (discontinues strand).

Thank you.