Background information:

1.       Temperature-sensitive cell cycle (cdc) mutants are important tools for studying cell cycle. These mutants grow and divide normally at low temperature but express the mutant phenotype at higher temperature.

2.       Hydroxyurea inhibits the enzyme ribonucleotide reductase, and thus blocks DNA synthesis. Hydroxyurea inhibition of cell cycle can be overcome by changing the incubation media to remove the drug.

Experimental design and results:

A.      A culture of cdcx mutations is incubated at 37°C for two hours (the approximately length of the cell cycle in yeast), and then transferred to a medium containing hydroxyurea at 20°C.

a.       None of the cdcx mutants divide.

B.      You first incubate cdcx cells at 20°C for 2 hours with hydroxyurea, and then transfer them to a medium without the drug at 37°C.

a.       The cdcx mutants divide once.

C.      You repeat these two experiments with the cdcy mutant cells.

a.       The cdcy mutant cells do not divide in either experiment.

·         Identify what phase of the cell cycle the cdcx mutant cells are blocked at for the restrictive temperature. Provide reasoning.

·         Identify what phase of the cell cycle the cdcx mutant cells are blocked at for the restrictive temperature. Provide reasoning.

1. Imagine you have two beakers: one with 750 ml of sea water and one with 750 ml of distilled water. You bubble CO2 into each and take the pH of each solution every minute for 15 minutes.

Q1: Why did pH decrease when CO₂ was added to water and sea water?

Q2: Why did the pH of the water decrease more quickly than the sea water?

1. Explain how the buffer system in our blood is related to ocean acidification.

According to the video “Changing Waters on the Oregon Coast”:

1: What aquatic organisms are most vulnerable to ocean acidification?

Q2: Why will the Oregon coast continue to see an increase in ocean acidification for 30-35 years even if we were to completely stop CO2 emissions today and cap the atmospheric levels?

How would you determine whether a colorless colony on MacConkey agar is Salmonella or Shigella? Why would you want to identify a colorless colony? Briefly explain

Is Genetic Engineering of humans a good thing or a bad thing?

The Pasteur Effect

In 1861 Louis Pasteur observed that yeast, a facultative anaerobe, could grow in a sugar and protein broth without air, i.e. Oxygen. For every gram of yeast in a culture, 60-80 grams of sugar disappeared from the broth. When the yeasts are cultured with air 4-10 grams of sugar are consumed for every gram of yeast added to the culture. When the yeasts were cultured only on protein broth, only yeast culture with air grew. Below is a table that summarizes the conditions that allowed the yeast to grow.

• How does this data demonstrate yeast are facultative anaerobes?
• Is the ratio of sugar required without oxygen compared to the sugar required with oxygen like the ratio of ATP produced with fermentation and with aerobic respiration?
• How did the yeast without sugar grow?
• Why did the yeast with only protein in the broth require oxygen to grow?
• Explain the Pasteur Effect.

Compare and contrast the kidneys between fish, Amphibians, and Mammals. What are the differences and similarities? What does a loop of henle allow, what happens to the ability of a mammal that has a longer loop?

Genetic engineering of microorganisms involved in MLF of wine has only been partially successful, why?

In a typical microbiology laboratory, reasons for no bands from a gel of a polymerase chain reaction may be due to errors relating to omission of ingredients in the reaction mix and absence of the target sequence in the template DNA. Based on (i) primer problem and (ii) purity/potential contamination of the target sequence, explain the reasons for non-appearance on bands.

1. (i) Explain why it is important to assign individuals to species. (ii) What is a species concept? (iii) Name and formally define one species concept. (iv) Explain ONE of the weaknesses associated with the concept named in (iii). Critically discuss the question of what is a species? please NO hand writing. explain in more details.  

1) how can the knowledge on the metabolism of parasite be used for effective control strategy

2) discuss carbohydrate metabolism in protozoans

3)most protozoans under go anaerobic metabolism.discuss