the thermodynamic parameters indicate that the _______ of duplex DNA is enthalpically opposed and entropically favored, while the _________ of duplex DNA is enthalpically favored and entropically opposed (hint: see the discussion of entropy in Chapter 1).

melting; formation

formation; melting

Draw the signal transduction pathway that occurs in the outer segment of vertebrate photoreceptors. Be sure to describe what the components are and what they do (half a sentence each)

The outer covering of an adult sea squirt is called the .

mantle

exoskeleton

shell

tunic

Why are sponges considered metazoans and all other animals considered eumetazoans?

What do bivalves and tunicates have in common?

On an isolated island you discover a vertebrate animal that has never been described before. It has feathers, a feathered, bird-like tail, lays hard-shelled eggs and can fly, but it has teeth instead of a beak. Provide an explanation for the evolution of this animal and possible relationship with other clades of vertebrates that accounts for this unusual combination of features.

The E. coli trp operon encodes proteins involved in the biosynthesis of the amino acid tryptophan. Control of trp operon expression is mediated by two distinct regulatory mechanisms. Describe these two regulatory mechanisms in detail.

Note

Please give detail and comprehensive answer .

A lipid bi-layer membrane can be described as a “fluid mosaic”, with free lateral diffusion and almost no unassisted flipping. What are the features of lipids and lipid bi-layers that contribute to these characteristics?

Question 9 [10 marks / 10 minutes]
Suppose there are two different mutant alleles of the same gene. Sequence analysis shows that both alleles are single nucleotide substitutions, and that different nucleotide positions within the gene are affected in each allele. Phenotypic analysis shows that one allele is a null allele, and the other is dominant negative (antimorphic).
Explain what this information reveals about the two mutations. Give a hypothesis for how these two mutant alleles could show such markedly different effects. [10 marks]

Question 11 [10 marks / 10 minutes]
For the mutations in the 5’ UTR of the trp operon given below, explain the effect on expression of the trp operon relative to wildtype (increased, decreased, or unchanged).
Assume medium levels of tryptophan, such that TrpR (repressor) is inactive and attenuation is active.
a) A mutation in region 2 such that it cannot bind with region 3. [4 marks]
b) A mutation in region 4 such that it cannot bind with region 3. [4 marks]
c) Insertion of T-A basepairs immediately after region 3, such that uracils are transcribed. This insertion does not change the stem-loop formation properties of regions 1, 2, 3 or 4. [2 marks]

1. Unbeknownst to Joe, his bout of enteritis severely injures his pancreas and he unknowingly has developed type 1 diabetes. Describe the disease progression that Joe went through before diagnosis and how he was treated.

2. Describe how caloric excess excess leads to disease

1. Briefly describe three ways that insulin is stimulated? A direct response to high glucose is not an acceptable answer.

2. What is the clinical relevance of detecting glucose in the urine?

1. what is a virus?
What are the causes of the common cold?

Most vitamins are cofactors or coenzymes. What happens if we do not consume enough vitamins in our diet (specifically to the enzymes that use them)?

Several international students have performed a glucose tolerance test as part of a scientific study of lactase persistence. Here are the results:

1. Draw line graphs (all on the same grid) to show this data visually. Use a different color for each person.

2. Based on your graph, divide these students into two groups.

3. Imagine that the same test had been done on these individuals as babies. What do you predict the shape of the graph would be like? EXPLAIN your reasoning.

4. When someone takes a blood glucose test, they are usually asked to fast for twelve hours before the test. Why do you think this is done?

5. Would it be a mistake to consider blood glucose level a proxy data? EXPLAIN.

Assuming 1.5 ATP per FADH, 2.5 ATP per NADH in mitochondria, compare approximately how many ATP equivalents would be generated from the complete oxidation of 12-carbon worth of

a. saturated fatty acid

b. sugar (e.g. glucose)

Show work (possibly drawing out the cycle).