Question

1-Describe what happens to the slope of the exponential phase for a population of tetracycline resistant bacteria growing in the presence of the antibiotic tetracycline. Explain what you have described.

2-In the article New Antibiotics Discovered by Sifting Through the Human Microbiome, the researchers discovered genes coding for the production of beta lactams, which targets bacterial cell wall synthesis. Because of this, beta lactams would be considered

a) Lysogenic

b) Cidal

c) Synthetic

d) Static

e)Exergonic

3-Hydroxychloroquine is used to control the replication of which of the following?

a)Plasmodium

b)Trypanosoma

c)Penicillium

d)Pseudomonas

e)Saccharomyces

4-. Nucleotide analogs stop DNA and RNA synthesis because they

a)Are not recognized by DNA or RNA polymerases

b)Do not allow the next nucleotide base to attach

c)Get incorporated by the ribosome

d)Are produced in high amounts by the cell’s metabolism

e)Are only used by eukaryotic cells

Answer 1

1. In a bacterial growth curve the exponantial phase is marked rapid increase in in number with a constant proportion. However the growth phase is largely dependent on the environmental conditions like avalibility of nutrition , temperature etc. If antibiotic is present in a bacterial culture then the susceptible bacteria will not show any exponantial phase and constantly they will die. But if a bacterial population is resistance to certain antibiotic (for examle tetracycline ) then the growth curve will be unaffacted even in the presence of the particular antibiotic. Eventually they will show normal exponental growth if other factors are remain constant.

2. beta lactam is a group of antibiotics that inhibit bacterial cell wall synthesis. So, if beta lactam is present then all of the bacteria will die due to the lack of cell wall. Hence the effect of beta lactam is considered as Cidal (capable of killing).

In bacteriostatic, bacteria will show slow growth but with beta lactam they will die.

3. Hydroxychloroquine is used to control the replication of Plasmodium

The drug is largely used in controlling of malaria caused by Plasmodium vivax.

4. Nucleotide analogs stop DNA and RNA synthesis because they Do not allow the next nucleotide base to attach

when nucleotide analouges are incorporated in a growing DNA/RNA chain by DNA or RNA pol , they prevent the chain exension and addition of any further nucleotides.

The others options are wrong because- They do recognized by polymerase (not by ribosome) and subsequently incorporated in the growing chain.