Question

1. What is the Central Dogma of genetics? -- EXPLAIN
2. Corynebacterium diptheriae, the causative agent of diptheria, secretes a toxin that enzymatically inactivates all molecules of elongation factor in a eukaryotic cell. What immediate and long-term effects does this have on the cellular metabolism of an infected person? -- EXPLAIN
3. What is the difference between horizontal gene transfer and vertical gene transfer? -- EXPLAIN
4. After running gel electrophoresis, what do the black bands represent? What can those bands tell us, and how? – EXPLAIN
5. Which statement accurately describes differences between RNA and DNA? Select one

a. The sugar in DNA contains one less hydroxyl group than the sugar in RNA.

b. RNA always folds into a single helix while DNA always folds into a double helix.

c. RNA contains the nitrogenous base thymine, while DNA contains the nitrogenous base uracil.

d. RNA contains pyrimidine bases, while DNA contains purine bases.

e. The nucleotides in DNA contain one phosphate group while those in RNA contain two phosphate groups.

6. What type of bonds are located between the nucleotides found in opposing DNA strands (i.e. the strands that are across from each other)? Select one:

a. hydrogen bonds

b. hydrophobic interactions

c. van der walls interaction

d. ionic bonds

e. phosphodiester bonds

7) Which of the following nucleotide sequences represents the complement to the DNA strand 5' TAA CAG ACT 3' ?Select one:

a. 5' AGT CTG TTA 3'

b. 3' CGG TGA GTC 5'

c. 3' TAA CAG ACT 5'

d. 3' AGT CTG TTA 5'

e. 3' ATT GTC TGA 5'

8)  When DNA is subjected to high temperatures, what happens? Select one:

a. The antiparallel strands reorient themselves to become parallel.

b. The hydrogen bonds that hold the strands together are broken.

c. The DNA molecule crystalizes.

d. The DNA strand breaks into individual nucleotides.

e. The double helix converts into a triple helix.

9)If bacterial cells were treated with a chemical known to cause DNA damage, the resulting mutations would be considered Select one:

a. spontaneous.

b. transductive.

c. induced.

d. horizontal.

e. silent.

10) What term refers to short DNA strands that are used as the starting points for DNA synthesis during PCR? Select one:

a. restriction enzymes

b. DNA polymerases

c. vectors

d. mutagens

e. primers

11) What term refers to short DNA molecules that base-pair to very specific DNA or RNA sequences in a test sample, ultimately allowing for the visual identification of a specific DNA sequence? Select one:

a. primers

b. libraries

c. probes

d. DNA polymerase

e. restriction enzymes

Answer 1

1. Central Dogma of Genetics: It outlines the basic framework on how genetic information flows from DNA to the RNA (Transcription) and the synthesis of protein from the transcribed RNA (Translation). DNA → RNA → Protein.

2. The diphtheria toxin (DT) target is the diphthamide molecule (modified histidine amino acid residue) located on the translation elongation factor 2 (eEF2). This result in the immediate obstruction of protein synthesis machinery and the subsequent cell death. In long term, the DT will spread to the other region from the damaged tissues through blood and lymphatic channels.

3. Horizontal Gene Transfer: Transfer of genetic material between unrelated species. Example: Bacterial Transformation, Transduction and Conjugation. Vertical Gene Transfer: Transfer of genetic material from parent to offspring through sexual or asexual reproduction.

4. The black bands in gel electrophoresis represents DNA fragments stained with ethidium bromide. Since, the migration of DNA fragments through the agarose gel depends on their molecular weight, we get the information about resolved DNA fragments (or gene of interest) through gel electrophoresis technique.

5. Option (a) The  pentose sugar in DNA has hydrogen atom instead of hydroxyl group at 2' position.

6. Option (a) Hydrogen bonds between purines and pyrimidines.

7. Option (e) Complementary base pairing rule

8. Option (b) Denaturation event

9. Option (c) DNA damage-induced mutation

10. Option (e) Primers (Forward and Reverse)

11. Option (c) Probes (Hybridization)

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