Q: Adenine has a molecular formula of $$\mathrm{C_5H_5N_5}. $$What is the mass in Daltons (Da) of a single adenine molecule? (Atomic masses: C = 12 Da, H = 1 Da, N = 14 Da)

$$\mathrm{(5 \times 12) + (5 \times 1) + (5 \times 14) = 60 + 5 + 70 = 135\ Da}$$

Question 1

Adenine has a molecular formula of $$\mathrm{C_5H_5N_5}. $$What is the mass in Daltons (Da) of a single adenine molecule? (Atomic masses: C = 12 Da, H = 1 Da, N = 14 Da)

Accepted Answer

$$\mathrm{(5 	imes 12) + (5 	imes 1) + (5 	imes 14) = 60 + 5 + 70 = 135\ Da}$$

Question 2

How much does one mole of adenine ($$\mathrm{C_5H_5N_5}) $$weigh in grams? (Atomic masses: C = 12 g/mol, H = 1 g/mol, N = 14 g/mol)

Accepted Answer

$$\mathrm{135\ g}$$

Question 3

How many covalent bonds are present in a single adenine molecule ($$\mathrm{C_5H_5N_5}$$), assuming the typical bonding patterns for C, H, and N? (Count double bonds as TWO covalent bonds.)

Accepted Answer

15

Question 4

In the adenine molecule, how many polar covalent bonds are present? (Recall that C–N and N–H bonds are polar, while C–C and C–H are nonpolar.)

Accepted Answer

6

Question 5

How many atoms in adenine have undergone $$sp^3$$ hybridization?

Accepted Answer

2

Question 6

Which functional group found in nucleotides, DNA, and RNA is acidic at cellular pH?

Accepted Answer

Phosphate group

Question 7

A researcher isolates a nucleotide and finds it contains a group that can donate a proton at physiological pH. Which group is most likely responsible for this property?

Accepted Answer

Phosphate group

Question 8

If a molecule contains only C–H and C–C bonds, what can you infer about its polarity?

Accepted Answer

It is nonpolar because both C–H and C–C bonds are nonpolar.

Question 9

Which of the following best describes the difference between a gram and a Dalton?

Accepted Answer

A Dalton is the mass of one atomic mass unit, while a gram is a macroscopic unit of mass.

Question 10

Adenine contains several nitrogen atoms. Which type of covalent bond is most likely to form between carbon and nitrogen in adenine?

Accepted Answer

Polar covalent bond

Question 11

Which of the following statements about $$sp^3$$ hybridization is correct?

Accepted Answer

An atom with $$sp^3$$ hybridization forms four single bonds in a tetrahedral geometry.

Question 12

A mutation changes a nucleotide in DNA, replacing a phosphate group with a methyl group. What is the most likely effect on the molecule's charge at cellular pH?

Accepted Answer

The molecule will become less negatively charged.

Question 13

Which of the following best explains why the phosphate group is acidic at cellular pH?

Accepted Answer

It can donate a proton ($$\mathrm{H^+}) to $$the solution.

Question 14

Which of the following bonds in adenine is most likely to be nonpolar?

Accepted Answer

C–H bond

Question 15

A scientist is analyzing the hybridization of atoms in adenine. Which statement is correct regarding the $$sp^3$$ hybridized atoms?

Accepted Answer

They are typically found at positions where the atom forms four single bonds.

Question 16

Which of the following functional groups is NOT typically found in nucleotides?

Accepted Answer

Carboxyl group

Question 17

If a molecule contains a double bond between two carbon atoms, how many covalent bonds does this double bond represent?

Accepted Answer

2

Question 18

Which of the following best describes the relationship between moles, grams, and Daltons?

Accepted Answer

One mole of a substance has a mass in grams equal to its molecular mass in Daltons.

Question 19

Which of the following is a real-world consequence of the phosphate group’s acidity in DNA and RNA?

Accepted Answer

DNA and RNA are negatively charged at physiological pH, affecting their interactions with proteins.

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