Biology Exam Chapter 17

1. Garrod hypothesized that 'inborn errors of metabolism' such as alkaptonuria occur because

B) enzymes are made of DNA, and affected individuals lack DNA polymerase.

A) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

C) many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA.

D) certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors.

Garrod's hypothesis focused on genetic defects leading to enzyme deficiencies, not directly related to the composition or interaction with DNA or other molecules.

Explanation

Garrod's hypothesis focused on genetic defects leading to enzyme deficiencies, not directly related to the composition or interaction with DNA or other molecules.

2. According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway?

A) 0

D) 3

C) 2

B) 1

Beadle and Tatum's hypothesis states that for a specific biochemical pathway, two genes are necessary for the pathway to function properly.

Explanation

Beadle and Tatum's hypothesis states that for a specific biochemical pathway, two genes are necessary for the pathway to function properly.

3. A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation?

A) an accumulation of A and no production of B and C

B) an accumulation of A and B and no production of C

C) an accumulation of B and no production of A and C

D) an accumulation of B and C and no production of A

In this scenario, a defective enzyme A would lead to the accumulation of A and a lack of production of B and C. This is because the defective enzyme is unable to convert A into products B and C, resulting in an excess of A.

Explanation

In this scenario, a defective enzyme A would lead to the accumulation of A and a lack of production of B and C. This is because the defective enzyme is unable to convert A into products B and C, resulting in an excess of A.

4. If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media?

B) minimal medium supplemented with nutrient 'A' only

D) minimal medium supplemented with nutrient 'C' only

C) minimal medium supplemented with nutrient "B" only

A) minimal medium

For growth, all three nutrients A, B, and C are required. Since the strain is mutant for enzyme A, it can only survive if nutrient B is supplemented in the medium to compensate for the absence of enzyme A.

Explanation

For growth, all three nutrients A, B, and C are required. Since the strain is mutant for enzyme A, it can only survive if nutrient B is supplemented in the medium to compensate for the absence of enzyme A.

5. If A, B, and C are all required for growth, a strain mutant for the gene encoding enzyme B would be capable of growing on which of the following media?

A) minimal medium

C) minimal medium supplemented with 'B' only

D) minimal medium supplemented with "C" only

B) minimal medium supplemented with 'A' only

For growth, A, B, and C are all required. Therefore, a mutant strain lacking enzyme B would not be able to grow in minimal medium alone or supplemented with only 'A' or 'B'. The mutant would only be capable of growing if supplemented with nutrient 'C' which is the missing essential component.

Explanation

For growth, A, B, and C are all required. Therefore, a mutant strain lacking enzyme B would not be able to grow in minimal medium alone or supplemented with only 'A' or 'B'. The mutant would only be capable of growing if supplemented with nutrient 'C' which is the missing essential component.

6. The nitrogenous base adenine is found in all members of which group?

C) ATP, RNA, and DNA

B) proteins, ATP, and DNA

A) proteins, triglycerides, and testosterone

D) alpha glucose, ATP, and DNA

Adenine is a nitrogenous base that is a component of nucleotides found in ATP, RNA, and DNA. It is not found in proteins, triglycerides, testosterone, or alpha glucose.

Explanation

Adenine is a nitrogenous base that is a component of nucleotides found in ATP, RNA, and DNA. It is not found in proteins, triglycerides, testosterone, or alpha glucose.

7. Why is using RNA as a template for protein synthesis instead of translating proteins directly from the DNA advantageous for the cell?

Only one mRNA molecule can be transcribed from a single gene, lowering the potential rate of gene expression.

TRNA, rRNA and others are not transcribed.

B) RNA acts as an expendable copy of the genetic material.

RNA is much more stable than DNA.

By using RNA as an expendable copy of the genetic material, the cell can safely carry out protein synthesis without risking damage to the original DNA. This allows for flexibility and adaptability in gene expression.

Explanation

By using RNA as an expendable copy of the genetic material, the cell can safely carry out protein synthesis without risking damage to the original DNA. This allows for flexibility and adaptability in gene expression.

8. If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?

B) 2

A) 1

D) 4

C) 3

In a genetic system with four different nucleotides, the minimum number of nucleotides required to code for 12 amino acids (2^x >= 12, where x is the number of nucleotides) is 2. This is because 2^2 = 4, which is the smallest power of 2 greater than 12.

Explanation

In a genetic system with four different nucleotides, the minimum number of nucleotides required to code for 12 amino acids (2^x >= 12, where x is the number of nucleotides) is 2. This is because 2^2 = 4, which is the smallest power of 2 greater than 12.

9. The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many artificial mRNA 3 nucleotide codons would be possible?

A) 3

B) 4

C) 8

D) 16

When adding polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate, the possible artificial mRNA 3 nucleotide codons would be 2^3 = 8, as there are 2 nucleotide options (A and G) at each of the 3 positions within the codon. This results in 8 unique combinations possible.

Explanation

When adding polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate, the possible artificial mRNA 3 nucleotide codons would be 2^3 = 8, as there are 2 nucleotide options (A and G) at each of the 3 positions within the codon. This results in 8 unique combinations possible.

10. A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be

A) 5' TTG-CTA-CAG-TAG 3'

B) 3' AAC-GAC-GUC-AUA 5'

D) 3' AAA-AAT-ATA-ACA 5'

The correct codon sequence for phe-leu-ile-val is AUG-CTG-CAG-TAT, which is in option C, the other options do not match the correct sequence.

Explanation

The correct codon sequence for phe-leu-ile-val is AUG-CTG-CAG-TAT, which is in option C, the other options do not match the correct sequence.