Anabolic Pathways and Synthesis

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1

What is the likely genetic make-up of a virus which contains a RNA-dependent RNA polymerase?

Minus-strand RNA

Plus-strand RNA

Single-stranded DNA

Double-stranded DNA

Double-stranded RNA

Explanation

We're given the type of enzyme contained within a virus, and we're asked to make a determination of the virus' genetic makeup.

To begin with, we're told that the enzyme is an RNA-dependent RNA polymerase. The name of the enzyme gives us insight into what it does. It requires RNA as a template to produce more RNA.

So if this enzyme can convert RNA into RNA, where does the original RNA come from? The answer is that it must come from the virus. This means that we must be dealing with single-stranded RNA.

Now, the question is to determine the sense of the RNA genome of the virus. That is to say, it can be minus or plus. A minus-sense RNA is one whose complementary sequence can be translated into protein. A plus-sense RNA is one that doesn't need any processing to be translated. Rather, plus-sense RNA can be translated right away. Since we know that the enzyme present is going to produce RNA from RNA, we can then reason that the viral genome is likely minus-sense. When the minus-sense RNA is enacted on by this enzyme, the result is a new strand of RNA that can be translated into protein to serve the needs of the virus.

2

What is the likely genetic make-up of a virus which contains a RNA-dependent RNA polymerase?

Minus-strand RNA

Plus-strand RNA

Single-stranded DNA

Double-stranded DNA

Double-stranded RNA

Explanation

We're given the type of enzyme contained within a virus, and we're asked to make a determination of the virus' genetic makeup.

To begin with, we're told that the enzyme is an RNA-dependent RNA polymerase. The name of the enzyme gives us insight into what it does. It requires RNA as a template to produce more RNA.

So if this enzyme can convert RNA into RNA, where does the original RNA come from? The answer is that it must come from the virus. This means that we must be dealing with single-stranded RNA.

Now, the question is to determine the sense of the RNA genome of the virus. That is to say, it can be minus or plus. A minus-sense RNA is one whose complementary sequence can be translated into protein. A plus-sense RNA is one that doesn't need any processing to be translated. Rather, plus-sense RNA can be translated right away. Since we know that the enzyme present is going to produce RNA from RNA, we can then reason that the viral genome is likely minus-sense. When the minus-sense RNA is enacted on by this enzyme, the result is a new strand of RNA that can be translated into protein to serve the needs of the virus.

3

What two molecules are the links between the urea cycle and gluconeogenesis?

Fumarate and aspartate

Fumarate and citrate

Citrate and aspartate

Oxaloacetate and fumarate

Oxaloacetate and citrate

Explanation

Aspartate can form arginosuccinate, which can then release a fumarate molecule. The fumarate can enter into the Krebs cycle and eventually the pathway can lead to gluconeogenesis. The arginine from the arginosuccinate can continue through the urea cycle.

4

What two molecules are the links between the urea cycle and gluconeogenesis?

Fumarate and aspartate

Fumarate and citrate

Citrate and aspartate

Oxaloacetate and fumarate

Oxaloacetate and citrate

Explanation

Aspartate can form arginosuccinate, which can then release a fumarate molecule. The fumarate can enter into the Krebs cycle and eventually the pathway can lead to gluconeogenesis. The arginine from the arginosuccinate can continue through the urea cycle.

5

What is the likely genetic make-up of a virus which contains a RNA-dependent RNA polymerase?

Minus-strand RNA

Plus-strand RNA

Single-stranded DNA

Double-stranded DNA

Double-stranded RNA

Explanation

We're given the type of enzyme contained within a virus, and we're asked to make a determination of the virus' genetic makeup.

To begin with, we're told that the enzyme is an RNA-dependent RNA polymerase. The name of the enzyme gives us insight into what it does. It requires RNA as a template to produce more RNA.

So if this enzyme can convert RNA into RNA, where does the original RNA come from? The answer is that it must come from the virus. This means that we must be dealing with single-stranded RNA.

Now, the question is to determine the sense of the RNA genome of the virus. That is to say, it can be minus or plus. A minus-sense RNA is one whose complementary sequence can be translated into protein. A plus-sense RNA is one that doesn't need any processing to be translated. Rather, plus-sense RNA can be translated right away. Since we know that the enzyme present is going to produce RNA from RNA, we can then reason that the viral genome is likely minus-sense. When the minus-sense RNA is enacted on by this enzyme, the result is a new strand of RNA that can be translated into protein to serve the needs of the virus.

6

What two molecules are the links between the urea cycle and gluconeogenesis?

Fumarate and aspartate

Fumarate and citrate

Citrate and aspartate

Oxaloacetate and fumarate

Oxaloacetate and citrate

Explanation

Aspartate can form arginosuccinate, which can then release a fumarate molecule. The fumarate can enter into the Krebs cycle and eventually the pathway can lead to gluconeogenesis. The arginine from the arginosuccinate can continue through the urea cycle.

7

Which of the following carbohydrates cannot be continuously linearized with glycosidic bonds?

Sucrose

Lactose

Glycogen

Galactose

Explanation

In order to linearize using a linkage, there needs to be an unbound carbon on the 1 position. However, sucrose is a linkage and doesn't have a carbon available to linearize in the 1 position. It isn't a reducing sugar and therefore cannot be linearized. All of the other sugars have their anomeric carbon located at the 1 position and all of them are reducing sugars that can be linearized.

8

Which of the following carbohydrates cannot be continuously linearized with glycosidic bonds?

Sucrose

Lactose

Glycogen

Galactose

Explanation

In order to linearize using a linkage, there needs to be an unbound carbon on the 1 position. However, sucrose is a linkage and doesn't have a carbon available to linearize in the 1 position. It isn't a reducing sugar and therefore cannot be linearized. All of the other sugars have their anomeric carbon located at the 1 position and all of them are reducing sugars that can be linearized.

9

Which of the following carbohydrates cannot be continuously linearized with glycosidic bonds?

Sucrose

Lactose

Glycogen

Galactose

Explanation

In order to linearize using a linkage, there needs to be an unbound carbon on the 1 position. However, sucrose is a linkage and doesn't have a carbon available to linearize in the 1 position. It isn't a reducing sugar and therefore cannot be linearized. All of the other sugars have their anomeric carbon located at the 1 position and all of them are reducing sugars that can be linearized.

10

Which of the following is/are true regarding prokaryotic RNA polymerases?

I. RNA polymerase requires the sigma protein factor to initiate transcription.

II. Prokaryotes have multiple types of RNA polymerase.

III. RNA polymerase requires the rho protein factor to terminate transcription.

IV. Sigma protein is not required for RNA polymerase to initiate transcription in prokaryotes.

I and III

I and IV

I, II, and III

II, III, and IV

I and II

Explanation

There are few differences between prokaryotes and eukaryotes in what concerns transcription. In prokaryotes there is only one RNA polymerase, while in eukaryotes there are three: I , II and III. In prokaryotes, both sigma factor and rho factor are required for transcription to occur, but not in eukaryotes.

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