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

5) b) rna is single stranded but whereas dna is double helx

6) phosphodiester bond

7) a) 5'AGT CTG TTA 3'

10)e) primers

Answer 2

1. The Central Dogma of Genetics: The Central Dogma of genetics is a fundamental principle that describes the flow of genetic information within a cell. It states that genetic information flows in one direction, from DNA to RNA to protein synthesis. The process involves three main steps:

2. DNA Replication: DNA serves as the template for the synthesis of new DNA molecules through a process called DNA replication. During replication, the DNA double helix unwinds, and each strand serves as a template for the assembly of a complementary strand, resulting in two identical DNA molecules.

3. Transcription: The genetic information in DNA is transcribed into messenger RNA (mRNA) through a process called transcription. During transcription, an enzyme called RNA polymerase synthesizes a complementary mRNA strand using the DNA template. The mRNA carries the genetic code from the DNA to the ribosomes in the cytoplasm.

4. Translation: The genetic code carried by mRNA is translated into a specific sequence of amino acids to form a protein. This process occurs on ribosomes in the cytoplasm. Transfer RNA (tRNA) molecules bring the appropriate amino acids to the ribosome based on the codons (three-letter sequences) on the mRNA, and the amino acids are linked together to form a polypeptide chain, which then folds into a functional protein.

5. Effects of Corynebacterium diphtheriae Toxin on Cellular Metabolism: The toxin secreted by Corynebacterium diphtheriae inactivates the elongation factor in a eukaryotic cell. Elongation factors are essential for protein synthesis during translation. The immediate and long-term effects of this toxin on the cellular metabolism of an infected person are as follows:

Immediate Effects:

1. Inhibition of Protein Synthesis: Inactivation of elongation factors prevents the addition of amino acids to the growing polypeptide chain during translation, leading to a halt in protein synthesis. This impairs the cell's ability to produce essential proteins for its functions.

2. Disruption of Cellular Functions: Proteins are key players in various cellular processes, and their absence or reduced production disrupts normal cellular functions. This can lead to malfunctioning of cellular machinery and processes.

Long-Term Effects:

1. Cellular Damage and Death: Prolonged inhibition of protein synthesis due to the toxin can lead to cellular damage and eventual cell death. Tissues and organs that heavily rely on protein synthesis will be particularly affected.

2. Systemic Impact: The toxic effects of Corynebacterium diphtheriae can lead to systemic complications, affecting multiple organs and systems in the body. This can result in severe health consequences and potentially fatal outcomes.

3. Immune Response: The presence of the toxin triggers the immune system's response, leading to inflammation and the activation of immune cells. In severe cases, an excessive immune response can lead to tissue damage and further complications.

Overall, the secretion of the toxin by Corynebacterium diphtheriae interferes with protein synthesis, leading to immediate disruptions in cellular metabolism and long-term consequences on the infected person's health.

3. Horizontal Gene Transfer vs. Vertical Gene Transfer: Horizontal Gene Transfer (HGT) and Vertical Gene Transfer (VGT) are two mechanisms by which genetic material is transferred between organisms. Here's an explanation of each:

Horizontal Gene Transfer: Horizontal Gene Transfer is the process by which genetic material is transferred between organisms of the same generation, but not through direct parent-to-offspring inheritance. It allows genetic material to move between different species or even unrelated organisms. HGT can occur through various mechanisms, such as transformation (uptake of free DNA), transduction (transfer of DNA by viruses), and conjugation (direct transfer of DNA between bacterial cells).

Vertical Gene Transfer: Vertical Gene Transfer is the process of genetic material transfer from parent organisms to their offspring during reproduction. This is the classical mode of genetic inheritance, where genetic information is passed from one generation to the next through sexual or asexual reproduction.

Difference between HGT and VGT: The main difference between Horizontal Gene Transfer and Vertical Gene Transfer is the direction of gene transfer and the organisms involved. In HGT, genetic material moves laterally between organisms of the same generation and can occur between unrelated species. In contrast, VGT involves the transmission of genetic material from parents to offspring and is responsible for maintaining genetic continuity within a species.

4. Gel Electrophoresis and Black Bands: Gel electrophoresis is a laboratory technique used to separate and analyze DNA, RNA, or proteins based on their size and charge. In this technique, an electric field is applied to a gel matrix, and molecules are forced to move through the gel based on their charge and size.

The black bands observed after gel electrophoresis represent the migration of DNA fragments through the gel. Shorter DNA fragments move faster and travel farther in the gel, while longer fragments move more slowly and stay closer to the starting point.

These bands can provide valuable information about the size and quantity of DNA fragments present in the sample. By comparing the positions of the bands with known DNA markers of known sizes, researchers can determine the size of the DNA fragments in the sample. Additionally, the intensity of the bands (darker or lighter) can give an indication of the abundance or quantity of a particular DNA fragment in the sample.

5. Differences between RNA and DNA: The correct statement describing differences between RNA and DNA is:

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

Explanation: The main difference between RNA and DNA lies in their sugar moieties. DNA (deoxyribonucleic acid) has a deoxyribose sugar, which lacks one hydroxyl group at the 2' carbon position, while RNA (ribonucleic acid) has a ribose sugar with a hydroxyl group at the 2' carbon position.

Other statements mentioned are not correct: b. RNA can also fold into single or double helix structures depending on the type (e.g., single-stranded RNA vs. double-stranded RNA). c. DNA contains the nitrogenous base thymine, while RNA contains the nitrogenous base uracil. This statement is true, but it does not describe the difference in the sugar moiety. d. RNA contains pyrimidine bases (uracil and