A cell is LEAST likely to require a transport protein to move which of the following molecules across its membrane?:

(A) Sucrose

(B) Hydrogen ions

(C) Carbon dioxide

(D) Chloride ions

Although mitosis and meiosis share some similarities, they differ in several significant ways. In an essay of between 100-150 words, give one purpose of mitosis and one purpose of meiosis. Explain why these purposes are important

Ebola virus is a virus that is frequently and rapidly lethal in humans. The envelopes around particles of Ebola virus are studded with a viral glycoprotein (GP). Researchers hypothesized that, to enter a human cell, GP molecules must be cleaved by a protease enzyme, after which they bind with a protein called NPC1 in the human cell membrane. Reptile cells do not normally express the NPC1 protein, but the researchers modified some reptile cells to express NPC1. They then exposed the unmodified and modified cells to Ebola virus, both in the presence of a protease inhibitor that prevents GP cleavage, and without that inhibitor present. They then measured the frequency at which Ebola viruses infected the cells. These treatments are summarized below. I. Unmodified reptile cells, protease inhibitor absent II. Unmodified reptile cells, protease inhibitor present III. Modified reptile cells, protease inhibitor absent IV. Modified reptile cells, protease inhibitor present V. Unmodified human cells, protease inhibitor absent Of the following, which is a correct reason for including group V? :

(A) If the virus cannot enter group V but can enter group III, it shows that GP cleavage is not necessary for infection.

(B) If the virus can enter group V but cannot enter group IV, it shows that NPC1 is necessary for infection.

(C) If the virus can enter group V but cannot enter groups I, II, III, or IV, it shows that both GP cleavage and NPC1 are necessary for infection.

(D) Group V is a positive control.

A brown-eyed, right-handed man marries a blue-eyed, right-handed woman. Their first child is blue-eyed and left-handed. What are the chances of having another child who is blue-eyed and left-handed?

A) 25

B) 12.5

C) 75

D) 50

1.     How does each of your mutations affect the amino acid sequences? Are the mutations missense mutations, silent mutations or nonsense mutations?

a.     Point mutation?

b.     Frameshift-insertion?

c.     Frameshift-deletion?

2.     What differences did you notice between the point mutation and the frameshift mutations?

3.     Is it possible to determine the DNA sequence from the following amino acid sequence?: Leu Pro Arg. Why or Why not?

References:

Complete the following statements to describe how independent assortment contributes to genetic variation. Not all choices will be used.

During independent assortment, ____________ chromosomes separate.

This separation is ____________ ; it is due to their alignment down the metaphase plate.

The maternal or paternal homologue may be oriented toward either ____________ .

This randomized separation aids in genetic ____________ for offspring.

This variation helps in the long-term ____________ of the species.

Word Bank:

Complete the following statements of how meiosis increases genetic variation. Not all choices will be used.

Two events within meiosis increase variability. During prophase I, ____________ and crossing-over occurs.

This event allows for ____________ to break and rejoin.

This results in two chromosomes with a different combination of ____________ than they had before.

During metaphase I, homologous pairs align ____________ at a cell's equator.

This results in random separation of maternal and paternal chromosomes when the cell divides, creating ____________ combinations of final chromosome combinations in human cells.

Word Bank:

Complete the following statements to describe the differences between chromosomes and chromatin. Not all choices will be used.

Genetic material within the nucleus of a cell is typically arranged as ____________ , or long tangled collections of DNA and proteins.

During cell division, this DNA condenses into tightly coiled structures to form ____________ .

Humans have 46 of these; 22 of these pairs are called the ____________ and one pair is called the ____________ chromosomes.

These ____________ chromosomes control gender. Males have ____________ X chromosome and a Y chromosome, while females have ____________ X chromosomes.

Word Bank:

Complete the following statements to describe the differences between chromosomes and chromatin. Not all choices will be used.

Duplicated chromosomes called ____________ chromatids, contain the same genes.

They are held together by a region called the ____________ .

The chromatids remain together until a phase within mitosis, where the ____________ splits.

At this point, the chromatids separate and two individual ____________ chromosomes are fully formed.

Word Bank:

1. Provide a chemical reason for why Na+ ions are associated with ds-DNA relative to single strands.

2. The addition of Na+ ions stabilized ds-DNA. Can you suggest other types of chemical species that might also stabilize ds-DNA? What types of chemical species would destabilize ds-DNA?

Trace the fate of the isotopic label from [2-13C]-alanine to glucose

what are two ways that humans have altered the environment of fishes? pls give two examples of how these have negatively affected them. pls help

Amyloid precursor protein (APP) is an integral membrane protein with important functions at synapses between nerve cells. It is cleaved within the membrane to release an extracellular peptide fragment called Ab. When Ab peptides accumulate, they can aggregate to form amyloid fibrils associated with Alzheimer’s disease

The cleavage of APP to Ab is catalyzed by Presenilin-1. Presenilin-1 is inhibited by transition state analogues specific for aspartyl proteases.

A. In one sentence, describe why transition state analogues are excellent competitive inhibitors of enzymatic activity.

B. Presenilin-1 has two important catalytic residues, Asp257 and Asp385, which cleave APP to Ab within the hydrophobic membrane. Describe TWO reasons why these catalytic aspartates have elevated pKa values.

C. During catalysis, there is a buildup of negative charge on the oxygen atom of the scissile amide bond. To stabilize the transition state, Asp385 donates a proton to the oxyanion that forms. To what amino acid would you mutate Asp385 to prevent proton transfer whilst having minimal impact on the rest of the protein? Will this amino acid still be able to stabilize the transition state via hydrogen bonding?

D. Aspartyl proteases directly activate water for hydrolysis without forming a covalent enzyme-substrate intermediate. Draw a mechanism for peptide hydrolysis. Clearly show Asp385 stabilizing the oxyanion transition state. Clearly show what role Asp257 may have.

1. Generally speaking, overall do you think Americans are healthy? Why or Why not? Please describe some areas where we are healthy and some areas we are not healthy.   

2. Where do you think America's health care system rank? I am not looking for a specific number, but compared to the rest of the world, do we offer better health care, worse, about the same? Why-what makes it better, worse or the same?

3.   What do you think are the 3 biggest health concerns facing Americans? Why do you think these are the biggest concerns?

it is a tall plant with clear xylem and phloem, the gametophyte is dependent on the sporophyte and there are seeds. It could be either _______________.

1. Distinguish between “genome-wide” selective sweeps, versus “gene-specific” selective sweeps. Which of these would you expect to find in bacterial populations? Why? How could you distinguish between them? Discuss several reasons (as many as possible) why bacteria have evolved a somewhat higher error rate (in DNA replication) than multicellular animals.

Why are ribosomal proteins (and/or ribosomal RNAs) used for constructing a “universal tree of life”? Why are such trees usually presented in an “unrooted” form?

Describe the structure and function of wing coupling mechanisms in insects.

Which of the following is considered the LEAST important factor in controlling zonation in the rocky intertidal?

space competition

predation

salinity

desiccation tolerance