explain the role of lipids in maintaining the structure of the cell membrane.

Describe the principles of In-frame cloning

Describe the movement of Na⁺ and K⁺ in each event.

Events:

• Resting membrane potential
• Depolarization (rising phase)
• Falling phase
• Hyperpolarization

A tumor cell with a mutation in Rb can divide in the absence of extracellular signals.

A. If the Rb mutation is responsible for the increased cell division, is it likely that Rb is always active or always inactive? Explain your reasoning.

B. Which of the following molecules would be likely to block division of these tumor cells? Select all that would block division in cells with this Rb mutation.

       a. An inhibitor of Ras GEF

   b. A MAPK inhibitor

       c. An inhibitor of the G1 checkpoint Cdk

   d. An inhibitor of E2F (transcription factor regulated by Rb)

   e. An inhibitor of DNA polymerase

C. Explain why the choice/one choice in part B would block division of cells expressing this Rb mutant.

D. Explain why one of the choices in part B that you did NOT select would NOT block cell division in cell expressing this Rb mutant.

1. Draw a picture of a cell located in the intestines for yourself and label the surfaces and draw the location of the different receptors found on the plasma membranes. Then explain in your own words to turn in all of the different carrier proteins involved in the reabsorbtion of sodium and glucose from the intestinal mucosa to the blood.
2. What is the functional significance of tight junctions? Reflect on the fact that this is the same system involved in the kidneys for the reuptake of sodium and glucose in the kidney tubules. Why is that important to consider?
3. Draw a picture of a parietal cell located in the stomach for yourself. What protein carriers are important in the production and secretion of HCl in the stomach. How is this process influenced by carbon dioxide transport on the erythrocyte plasma membrane?
4. What is the importance of solute concentration on the reuptake of water in animal and plant cells?
5. How do vacuoles work? What is the importance of V-class H+ ATP-ase pumps in the uptake of water?
6. Channel proteins are typically involved in the import of ions across the plasma membrane. What are the major characteristics of potassium leak channels?
7. What is the importance of the water of hydration in the importance of movement of ions, like potassium, through channel proteins?
8. How is the Na+/K+ ATP-ase critical in the re-establishment of the resting membrane potential across the plasma membrane of animal cells.
9. How do voltage-gated ion channels work in the venus fly trap.
10. In anatomy and physiology, we discussed how nerve signals travel to the cochlear nerve allowing us to hear. Using your knowledge of anatomy and the information provided on the power point slides provided to you explain the role of stress-activated channels in this process.
11. Cholera toxin, a pathogenic intestinal bacterium, causes an indirect reduction in the activity of the Na+/K+-ATPase in intestinal epithelial cells. This results in reduced uptake of small sugars and amino acids from the intestine, as well as severe diarrhea. How are these two problems (eg. reduced nutrient uptake and diarrhea) coupled to impaired Na+/K+- ATPase function?
12. Like animal cells, the plasma membrane of plant cells has a membrane potential and plant cells also use cation-based symport for nutrient uptake. However, plant cells do not have Na+/K+-ATPase in their plasma membranes. Explain, then, how they establish and maintain a membrane potential and how they co-import nutrients in the absence of the Na+/K+ pump. Also explain how plant cell volume is regulated in light of this major difference.

Food Chains on the Isle of Dell

On the Isle of Dell, a large island with a variety of habitats and plant/animal species, the food chain has been left undisturbed by human development.  In the subtropical forests of the inland region, the elephants and rhinos forage on the native low shrubs. Inland water ways contain large schools of great goldfish which thrive on the indigo waterweed.   Nearer the coastal areas, donkeys, camels, and hippos consume the lush, green verdigrass. In the plains of the south, bison, horses, and cows rely on the tall, plains bushtail grasses as a staple of their diets.  The goats of the highlands graze over large areas in search of the dry goatweed.

The large wild cats of the islan, blend in with the bushtail grass, allowing them to stalk and prey upon the bison and cows.  Tigers on the island use their strength and speed to hunt down camels and donkeys along the coast.  In the highlands, lions use the rough terrain as cover to hunt the highly dispersed goat herds.  When goats are more difficult to find, lions do head to the coast and hunt camels and donkeys.  Bears living inland, traversing between both forests and plains, may actively hunt small, weak elephant, rhino, and cows, but mostly rely on the great goldfish and plains bushtail grass for their diets.

Based on the information above, fill out the two columns of the table below.

You have 2 strains of bacteria, strain 1 = trpA- trpB- trpC+ and strain 2 = trpA+ trpB+trpC-. You grow P1 transducing phage on strain 1 (you infect strain 1 with the phage), then infect strain 2 with this lysate and select for transductants on minimal medium (trpA,B,C mutants are all Trp auxotrophs). You get 1000 transductants growing with 0.1 ml lysate. You then infect strain 2 with your phage, then transduce strain 1 and get 15 transductants. a. What is the order of trpA, trpB, trpC? b. What is the genetic distance between trpA and trpC?

What is the role of polar auxin transport in embryo development?

Compare and contrasts meiosis and mitosis.  How do the behavior of chromosomes during meiosis generate variation and explain Mendel’s law of independent assortment? Long answer, please.

what is mean by doubling time? Has it gotten longer or shorter for the world's population? Cite and use actual numbers in your answer.

Explain why the motor proteins myosin and kinesin are enzymes and write the reaction that each catalyzes.