1. Attenuation is a regulatory mechanism that has been well studied in the E. coli trp operon, involved in tryptophan biosynthesis. Which of the following accurately describes attenuation?
A: The goal of attenuation is to suppress the expression of biosynthetic enzymes when the end product of the pathway is available.
B: The attenuator is a stem loop structure at the 5´ end of the mRNA transcript that resembles the structure of the factor-independent termination sequence.
C: When tryptophan levels are low, the trp operon transcript is attenuated before the operon's structural genes are transcribed.
D: Attenuation allows fine-tuning of the levels of mRNA transcript from the trp operon in response to small changes in the availability of tryptophan.
E: The trpL mRNA contains a "stall" sequence for the ribosome that includes two adjacent trp codons.

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2. Which of the following are true statements concerning the similarities and differences between prokaryotic and eukaryotic DNA replication:
A: Prokaryotes use DNA polymerase III as the primary replicative enzyme, whereas eukaryotes use DNA polymerase I.
B: Most prokaryotes replicate a single chromosome from a single origin of replication, whereas eukaryotes have thousands of origins of replication spread over multiple chromosomes.
C: In eukaryotes, DNA replication is continuous, whereas prokaryotes replicate their DNA discontinuously in a process that generates Okazaki fragments.
D: Eukaryotic DNA replication is more complex than prokaryotic replication, because eukaryotes must dissociate and replicate chromatin as part of the process.
E: A homodimer of DNA polymerase III catalyzes the replication of both leading and lagging strands in prokaryotes, whereas two different DNA polymerases are required to replicate the leading and lagging strands in eukaryotes.

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3. Ammonia is toxic and must be converted to urea in order to be excreted. The following statements describe the process:
A: ammonia is transported into the liver as either alanine or glutamine.
B: transamination is a key step in the release of ammonia from glutamine.
C: urea is formed and excreted primarily by the kidneys.
D: alanine carries ammonia waste from muscle to the liver; once in the liver, alanine is converted via pyruvate to glucose, which may be returned to the muscle.
E: carbamoyl phosphate is a key intermediate in the conversion of ammonia to urea.
F: urea is ultimately formed by hydrolysis from ornithine

Explain deviation from Mendel's model of the inheritance of traits(ie. his principles/theory of inheritance)  (.

please use the terms below in your answer)

Chi-square

Linked genes

map distance

Multiple alleles

Poly genic

Mitochondrial DNA

Maternal inheritance

In corn, the following allele pairs are on chromosome 9: colored (C) vs. white (c) aleurone color; starchy (Wx) vs. waxy (wx) endosperm; and full (Sh) vs. shrunken (sh) endosperm. F₁ plants heterozygous for all three alleles were test crossed; the resulting progeny had the following phenotypic ratios:

colored, waxy, shrunken 116

colored, starchy, full 601

colored, starchy, shrunken 2538

white, starchy, shrunken 4

white, starchy, full 113

white, waxy, full 2708

white, waxy, shrunken 626

colored, waxy, full _____2

6708

Determine the order of and distances between the three genes.  Also determine the coefficient of

coincidence (C) and the interference (I).

The undigested antibodies and pepsin digested antibodies were tested for haemagglutination. In the haemagglutination assay, the titre for undigested antibodies is 8 and pepsin digested antibodies is 4. why pepsin digested abs has lower titre compared to undigested abs. State 2 reason.

There are two ways to study receptor responsiveness in cultured cell lines: use a cell line that naturally expresses the receptor of interest; and transfect a cell line with a gene for the receptor you are interested in in order to ensure large numbers of this receptor. Taking into consideration what you know about G protein-coupled receptors and about measurement in pharmacology, briefly discuss what the possible advantage(s) and disadvantage(s) might be of each of these approaches.

fill the table.

Addison's disease develops when the adrenal cortex doesn't secrete enough mineralocorticoids and glucocorticoids. President John F. Kennedy was diagnosed with the disease when he was a young man. Before he started treatment with hormone replacement therapy, he was hypoglycemic and lost weight. Which missing hormone was responsible for his weight loss? How might Addison's disease have affected his blood pressure?

9. Which of the following
statements is true of a
tendon?
a. joins two bones over a
ball-and-socket joint
b. connects muscles to
bones
c. can be either fast-twitch
or slow-twitch type
d. is found between fibrous
and cartilaginous joints
10. Which muscle is an
example of an involuntary
muscle?
a. tongue
b. thigh
c. heart
d. bicep
11. The integumentary system
includes hair, fingernails,
and
a. skin.
b. tendons.
c. myosin.
d. marrow.

12. Which statement best
describes the subcutaneous
fat layer of your skin?
a. made up of mostly dead
cells, flaking away
b. is the outermost layer;
contains many pores
c. cushions large blood
vessels and neurons
d. contains cells that make
elastin and collagen
13. Which of the following
items is a pigment that
absorbs harmful ultraviolet
sunlight?
a. collagen
b. myosin
c. melanin
d. keratin
14. Sweat glands found in the
skin help maintain
homeostasis by
a. controlling body
temperature.
b. producing protective
proteins.
c. secreting antibacterial
fluids.
d. waterproofing the outer
skin.
15. Which set of characteristics
best describes the dermis?
a. contains glands that
produce oils or sweat
b. produces protective
melanin and keratin
c. insulates the muscles and
internal organs
d. consists of layered,
tough, waterproof protein

What is the name of the tissue lining the organs in the peritoneal cavity?

1. We know that an F+ cell can donate its F plasmid to a recipient cell to create a new F+ cell.

But what about an Hfr? Can an Hfr transfer its DNA as well? (yes/no) Please explain your answer. Why did you answer yes or no?

2. Let’s just assume,, that an Hfr cell could transfer DNA. What would the recipient cell look like? What would it be called? F+? F-? Hfr+? Something else altogether? Please explain your answer.

A group of scientists wants to determine if fin length variation is genetically or environmentally controlled. They think the presence of predator pressure may be an environmental determinant of fin length. The scientists take eggs from short-tailed parents and raise them in both low and high predator pressure environments. They also take eggs from long-tailed parents raise them in both low and high predator pressure environments. The scientists then evaluate the tail length of the fish hatched from the eggs at adulthood. Select the correct dependent variable for this experiment.

A.Level of predation pressure.

B.Tail length at adulthood.

C.Tail length of the parents of the eggs.

D.The eggs.