MET 2010 Lecture Notes - Lecture 2: Smog, Vapor Pressure, Stratus Cloud

Water is critical for life and is considered the universal solvent because of its unique properties. However, when temperatures drop below the freezing point of water, ice crystals form and can be lethal to cells. Cold-blooded organisms that live in cold climates have evolved mechanisms to cope with freezing temperatures, one of which is the synthesis of antifreeze proteins that block ice crystal growth. The larval antifreeze protein contains multiple stretches of 12 amino acids, repeating the sequence threonine-cysteine-threonine. The placement of the threonines in the repeating amino acid sequence positions hydroxyl groups at precisely the spacing needed to maximize hydrogen bond formation with the water at the leading edge of the ice crystal, and thereby blocks further growth of the crystal lattice.

QuestionGroup: #71 You and the environment3

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71

Recent reports indicate that the polar ice caps are melting. This melting will cause which of the following?

A

Increase in coastal flooding

B

A drop in atmosphere temperature

C

Increase in carbon dioxide in the atmosphere

D

Increase in inland flooding

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QuestionGroup: #72 Global warming

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72

How does incomplete combustion occur?

A

Incomplete combustion is the slow, lowtemperature, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel.

B

Incomplete combustion is a form of oxidation otherwise known as a fire, in which large amounts of heat and light energy are released, which often results in a flame.

C

Incomplete combustion will only occur when there isn't enough oxygen to allow the fuel to react completely to produce carbon dioxide and water.

D

Incomplete combustion, the reactant burns in oxygen, producing a limited number of products.

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QuestionGroup: #73 Global warming 2

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73

Chlorofluorocarbons have been banned due to which of the following?

A

They contribute to ozone depletion which increases global warming.

B

They contribute to ozone depletion which allows more radiation from the sun to hit the earth

C

They directly increase the concentration of carbon dioxide in the atmosphere.

D

They decrease the acidity of the oceans producing a more alkaline ocean

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QuestionGroup: #74 Drought

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74

Which of the following is the correct order of countries with the highest population?

A

USA, China, India

B

China, USA, India

C

China, India, USA

D

India, USA, China

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QuestionGroup: #75 Drought2

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75

Drought and flooding may occur in cycles. The result of flooding is that the water maybe contaminated with Cholera which is a major public safety concern. Which of the following points about Cholera is correct?

A

It is a bacteria that invades the stomach and can cause vomiting by causing the intestinal solution to be a hypotonic solution relative to the cells.

B

Cholera is found only in food and not in water. In flood situations, public sanitation is always maintained so people do not drinking contaminated water.

C

It is a bacteria that invades the intestinal tract and can cause diarrhea by causing the intestinal solution to have a hypertonic solution relative to the cells.

D

It is a virus that invades the stomach and can cause diarrhea by causing the intestinal solution to have a hypotonic solution relative to the cells became a major problem.

The bacterium E. coli, which is a major model system for the study of genes and DNA, has a singular circular chromosome of about 4x106 bp. In contrast, human diploid cells have __1__ chromosomes, of __2__ different types (don’t forget that the X ¹ Y!). The total amount of DNA found in a haploid cell such as a sperm or egg is called the organism’s “C-value”; the human C-value is __3__.

Also in contrast to the E. coli circular chromosome is the fact that eukaryotic chromosomes are not circular, but instead are __4__. Eukaryotic chromosomes are complexed heavily with protein to form a DNA-protein complex generically called __5__. The proteins found can be considered to fall into two general classes: __6__ and __7__. The first class is made up of 5 major proteins called __8__, __9__, __10__, __11__, and __12__. On a weight to weight basis, these proteins make up about __13__% of the total mass of a chromosome. Since these proteins must associate relatively non-specifically with DNA, they are rich in the basic amino acids __13__ and __14__, which gives the proteins a net __15__ charge.

One goal of packaging the DNA into chromatin is to compact the genome so it will fit into a nucleus. The basic unit of chromatin structure is the __16__, which has __17__ base pairs of DNA wrapped around a “core particle” composed of __18__ copies each of the core histones. Each nucleosome is separated by a stretch of “linker” DNA so that the repeating unit is approximately 200 bp. Lets do a little arithmetic: If we consider that the nucleosome is approximately __19__ nm in diameter, that there is about 200 bp in this structure, and that 200 bp of DNA would normally occupy __20__ nm if stretched out straight (recall that each base is spaced about 0.34 nm from the next), we can see that the nucleosome alone allows for a __21__-fold compaction ratio.

The nucleosome structure is further compacted by histone __22__, which is not a part of the core particle. Instead, this histone __23__ (does what?) to cause the nucleosomal 10 nm fiber to condense into a higher-order structure referred to as the __24__ nm fiber. In the nucleus, chromosomes do not just float around freely: they are tethered to a proteinaceous structure called the __25__ at specific DNA regions called “SARs”, which stands for __26__. SARs are rich in topoisomerases, to allow the winding and unwinding of the DNA that accompanies replication and transcription to occur, despite this constraint.

The 30 nm fiber discussed above is the form in which transcriptionally active DNA is believed to exist in the nucleus; however, further condensation leads to a highly condensed inactive form called __27__; in this terminology, the active form is referred to as __28__. The inactive condensed form can be divided into two types: one type is essentially invariant between cell types, and since it is “on all t time”, it is referred to as __29__. The other type comes and goes, depending on the expression of the genes present in that region of the chromosome; it is referred to as __30__.

Eukaryotic chromosomes carry the genes, of course, but also have other functional regions. One such region is the place where the spindle apparatus attaches during mitosis and meiosis; this region of the chromosome is called the __31__. Another important part of the linear eukaryotic chromosome is the ends; these are called __32__. In humans, the end of each chromosome is composed of many repeats of the short sequence __33__. One more type of functional region on each chromosome is the place where DNA replication starts; in humans, each chromosome has several of these __34__. Thus, eukaryotic chromosomes carry several different types of functional sequences, which together allow for their __35__ during S phase, __36__ during mitosis and meiosis, and the __37__ of their genes