You are studying a density-dependent elephant population that has the following relationships for the birth rate (b) and the death rate (d), as functions of N.

b=0.10+0.03N-0.0005N^2

d=0.20+0.01N

Plot these functions on the same graph (on a separate page). Using Excel can help you with this: plug into the equation a range of numbers for N from 1 to 60 or so elephants. How many equilibrium points are shown by your graph? You do not have to calculate the values of the equilibria, but indicate where they occur on the graph with arrows that show the population size at the equilibrium point(s) (2 points)

Stability is a quality of an equilibrium point such that when the population is perturbed away from that point, it will return to that equilibrium density. To determine the stability, predict what will happen when N is near, but not at, each equilibrium point and determine the trajectory of the population by comparing the relative magnitudes of b and d at your chosen points. Which one(s) of the equilibrium points are stable? Explain your reasoning. (2 points)

How does this model differ from the logistic growth equation? (1 point)

Research in cell biology and metabolism has progressed due to the discovery of molecules that artificially stimulate or inhibit glucagon/epinephrine and insulin signaling pathways. Let’s say you are working in a lab cataloging the effects of a library of small molecules on these pathways and have a “hit” on molecule 1stAVNGR. Preliminary data on molecule 1stAVNGR indicates that the cardiac isoform of PFK2/FBPase2 is doubly phosphorylated when this molecule is present at micromolar concentrations in cell cultures. Given this context answer the following questions.

a. Under these conditions what is the predicted degree of association between the regulatory subunits and the catalytic subunits of PKA?

b. Further investigation of molecule 1stAVNGR indicates elevated levels of cAMP within the cell despite the absence of epinephrine or glucagon. Hypothesize two possible explanations for this data.

c. When cell cultures are given both molecule 1stAVNGR and molecule RedSKLL (a G-protein inhibitor) cAMP levels remain high (again despite the absence of epinephrine or glucagon). Given this new information hypothesize a possible explanation for the data.

d. In consideration of the data presented in this problem what would be the expected effect of molecule 1stAVNGR on glycolytic flux in a culture of cardiac myocytes? Explain your reasoning?

e. Finally, if molecule 1stAVNGR were infused into a culture of hepatocytes what would be the expected effect on glycolytic flux in these cells? Explain your reasoning.

Whats the effect of the reeler mutation on cell-cell interaction

How does comparative anatomy support evolution?

DNA sequence may be used to identify different species. Assuming that you can use PCR to generate products for sequencing, describe in detail an experiment that will allow you to determine which strain of Salmonella has caused the more recent outbreak.

what does it mean to be alive? all life has some common characteristics such as:

list some characteristics of life you observed by the water bear: list some observations about the water bear and why its apparently so successful in a variety of environments

10.) In complex eukaryotes, what relationships exist between these DNA elements?

a. Centromeres, tandemly repeated DNA and constitutive heterochromatin

b.Interphase chromosomes, mitotic chromosomes, nucleosomes, histones.

c. Supercoiling and chromatin

11.) Which of the following statements is true?

a. Histones are an example of a sequence-specific DNA-binding protein.

b. The majority of human DNA is not known to be useful to our cells.

c. Human females have 23 different chromosomes, whereas human males have 24.

d. Because nucleosomes play a key role in packaging DNA into chromosomes, they bind to the DNA molecule very tightly and, once they are assembled, they cannot be moved.

e. A nucleosome consists of DNA wrapped around eight histone proteins, plus a short segment of linker DNA.

f. Nucleosomes are found only in mitotic chromosomes.

g. Histone proteins have a high proportion of positively charged amino acids, which bind tightly to the negatively charged DNA backbone.

12.) Micrococcal nuclease (MNase) is an enzyme that non-specifically cuts exposed DNA in its phosphodiester backbone. Brief digestion of eukaryotic chromatin with micrococcal nuclease gives DNA fragments ~200 bp long. You repeat the experiment, but incubate the samples for a longer period of time. This longer digestion yields 146 bp fragments. Why? Explain, using a diagram of the packaging of DNA by histone proteins into the basic unit of chromatin.

A pH gradient exists between the internal and external surfaces of the inner mitochondrial membrane of 1.4 pH units, where the external side is more acidic.

a. If the membrane potential is 0.6 V (where the internal side is negative), what is the free energy change on transporting 1 mol of protons across the membrane from outside to inside at 298 K?

b. Under standard state conditions, how many protons must be transported to provide enough free energy for the synthesis of 1 mol of ATP?

What are the main types of glial cells, and what is the main function of each? Glia outnumber neurons in the brain, yet neurons tend to be the focus of studies. Why?

The father of Mr. Spock, first officer of the starship Enterprise, came from the planet Vulcan. Mr. Spock’s mother came from Earth. Pure-bred Vulcans like Mr. Spock’s father have pointed ears (P), no adrenal glands (A), and a right-sided heart (R) and are homozygous for all of these alleles. These Vulcan alleles are dominant over normal earthling alleles. These three genes are autosomal, and they are linked as shown in this map:

P__15 map units_________A_____20 map units________R

If Mr. Spock marries a woman from Earth, what is the likelihood (expressed as a percentage or as a decimal) that their children would:

a) have Vulcan traits for all three of these characteristics?

b) have Vulcan ears, earthling adrenal glands, and earthling heart?

c) have Vulcan ears, earthling adrenal glands, and Vulcan heart?

6.) In the 1952 Hershey-Chase experiment showed that DNA is the genetic material of bacteriophage. Explain where the protein labeled with 35S ended up and where the DNA labeled with 32P ended up after centrifugation in their experiment. a. Draw a diagram of the experiment in support of your explanation. b. Is it possible to do the reverse labeling? (protein labeled with 32P and DNA is labeled with 35S) Why or why not?

7.) For each base-pair set, state if the two pairs are distinguishable using the minor groove, the major groove, or both. a. G:C vs. C:G ________ b. A:T vs. G:C _________

c. A:T vs. T:A _________

8.) Ethidum bromide (EtBr) is a large flat, multiringed cation. Its flat shape allows it to insert itself between the stacked base pairs of double stranded (dsDNA). Because it fluoresces when exposed to UV light and because its fluorescence increases dramatically after intercalation, it is used as a stain to visualize DNA. When ethidium intercalates it causes the DNA to unwind by about 26 degrees, reducing the normal rotation per base pair, decreasing the twist (T) of the DNA.

a. What effect would this change have on the writhe (W) of the plasmid?

b. When EtBr is used to visualize a relaxed covalently closed circular plasmid by gel electrophoresis, what effect would this have on the migration of the plasmid?

Concisely, describe the particular features of Creighton’s and McClintock’s experiment that allowed them to prove Morgan’s hypothesis that coupling and repulsion results from the physical exchange of DNA between homologous chromosomes?

A spontaneous mutation occurs in one of the copies of MT-TK, a gene found in mitochondrial DNA. MT-TK generates a tRNA required to make proteins formitochondrial function.

a. How can this mutation become deleterious?

b. In which parent and in which cells must this spontaneous mutation occur for it to be inherited? (hint: what happens if the mutation occurs in the heart.)

3.) Describe, to the best of your ability the bond chemistry behind the following attributes of DNA:

a. the double-strandedness

b. the antiparallel nature of the two strands.

c. the twist of the ladder into a helix.

4.) Griffith discovered that S. pneumoniae caused pneumonia in mice. In his experiments, mice were injected with different strains of treated and untreated bacteria. For each of the following, indicate whether the mice lived or died and why.

a. Mice injected with heat-killed S (smooth) strain

b. Mice injected with living S (smooth) and heat-killed R (rough) strain

c. Mice injected with heat –killed S and living R