ASU BIO 181 Exam 2 Question and Answer
2026/2027 | A+ Verified Updated | Exam Focus
• What are the 3 components of a nucleotide? -✓✓pentose (5' Carbon) sugar,
phosphate group, nitrogenous base
• What 5'C sugar is present in DNA? -✓✓Deoxyribose
• What 5'C sugar is present in RNA? -✓✓Ribose
• What are the nitrogenous bases found in DNA? -✓✓A, G, C, T
• What are the nitrogenous bases in RNA? -✓✓A, G, C , U
• Which nitrogenous bases are purines? -✓✓Adenine and guanine
• Which nitrogenous bases have 2 rings? -✓✓Purines (Adenine and guanine)
• Which nitrogenous bases are pyrimidines? -✓✓Cytosine, Uracil (in RNA), Thymine (in
DNA)
• Which nitrogenous bases have 1 ring? -✓✓Pyrimidines (Cytosine, uracil, thymine)
• How are nucleotides joined together? (Dehydration or hydrolysis?) -✓✓Dehydration
• What bond forms between complementary base pairs to hold the two strands of the
double helix together? -✓✓Hydrogen bonds
• Where are phosphodiester bonds formed? -✓✓Phosphate group in one nucleotide
(5'C) and the OH group (3'C) in the other nucleotide
• What is the backbone of a nucleotide strand made of? -✓✓Sugar and phosphate
(sugar-phosphate backbone)
• What shape does DNA form? -✓✓Double helix
• Are the 2 strands of DNA parallel or anti-parallel? -✓✓Anti-parallel
• A pairs with (in DNA) -✓✓T
• G pairs with -✓✓C
, • A pairs with (in RNA) -✓✓U
• What are Chargaff's rules? -✓✓#A's=#T's
#G's=#C's
#Purines=#Pyrimidines
• How many hydrogen bonds form between A & T/U? -✓✓2 hydrogen bonds
• How many hydrogen bonds form between G & C? -✓✓3 hydrogen bonds
• How is the single strand of DNA stabilized? -✓✓Phosphodiester bonds
• How is the double helix of DNA stabilized? -✓✓Hydrogen bonds
• Where is the attachment site for the phosphate group on a pentose sugar? -✓✓5' C
• Where is the attachment site for the nitrogenous base on a pentose sugar? -✓✓1' C
• What are the 3 main types of RNA? -✓✓rRNA, tRNA, mRNA
• What is the function of rRNA? -✓✓Synthesizes proteins
• What is the function of tRNA? -✓✓Delivers amino acids to ribosomes during protein
synthesis
• What is the function of mRNA? -✓✓Copies gene (DNA) and carries the info to
ribosomes
• What are the steps of the central dogma? -✓✓DNA -> RNA -> Protein
• What are genes? -✓✓DNA sequence that carries instructions to make one protein
• What is transcription? -✓✓Process of copying the information in DNA (gene) into
mRNA
• What are the 3 stages of transcription? -✓✓Initiation, elongation, termination
• What is the coding/non-template strand? -✓✓The DNA strand that has the same
sequence as the mRNA produced during transcription (except that thymine (T) in DNA
is replaced by uracil (U) in RNA)
• What is the template/non-coding strand? -✓✓The DNA strand that is complementary
to the RNA molecule being produced (and is read in the 3' to 5' direction, allowing RNA
polymerase to synthesize RNA in the 5' to 3' direction)
2026/2027 | A+ Verified Updated | Exam Focus
• What are the 3 components of a nucleotide? -✓✓pentose (5' Carbon) sugar,
phosphate group, nitrogenous base
• What 5'C sugar is present in DNA? -✓✓Deoxyribose
• What 5'C sugar is present in RNA? -✓✓Ribose
• What are the nitrogenous bases found in DNA? -✓✓A, G, C, T
• What are the nitrogenous bases in RNA? -✓✓A, G, C , U
• Which nitrogenous bases are purines? -✓✓Adenine and guanine
• Which nitrogenous bases have 2 rings? -✓✓Purines (Adenine and guanine)
• Which nitrogenous bases are pyrimidines? -✓✓Cytosine, Uracil (in RNA), Thymine (in
DNA)
• Which nitrogenous bases have 1 ring? -✓✓Pyrimidines (Cytosine, uracil, thymine)
• How are nucleotides joined together? (Dehydration or hydrolysis?) -✓✓Dehydration
• What bond forms between complementary base pairs to hold the two strands of the
double helix together? -✓✓Hydrogen bonds
• Where are phosphodiester bonds formed? -✓✓Phosphate group in one nucleotide
(5'C) and the OH group (3'C) in the other nucleotide
• What is the backbone of a nucleotide strand made of? -✓✓Sugar and phosphate
(sugar-phosphate backbone)
• What shape does DNA form? -✓✓Double helix
• Are the 2 strands of DNA parallel or anti-parallel? -✓✓Anti-parallel
• A pairs with (in DNA) -✓✓T
• G pairs with -✓✓C
, • A pairs with (in RNA) -✓✓U
• What are Chargaff's rules? -✓✓#A's=#T's
#G's=#C's
#Purines=#Pyrimidines
• How many hydrogen bonds form between A & T/U? -✓✓2 hydrogen bonds
• How many hydrogen bonds form between G & C? -✓✓3 hydrogen bonds
• How is the single strand of DNA stabilized? -✓✓Phosphodiester bonds
• How is the double helix of DNA stabilized? -✓✓Hydrogen bonds
• Where is the attachment site for the phosphate group on a pentose sugar? -✓✓5' C
• Where is the attachment site for the nitrogenous base on a pentose sugar? -✓✓1' C
• What are the 3 main types of RNA? -✓✓rRNA, tRNA, mRNA
• What is the function of rRNA? -✓✓Synthesizes proteins
• What is the function of tRNA? -✓✓Delivers amino acids to ribosomes during protein
synthesis
• What is the function of mRNA? -✓✓Copies gene (DNA) and carries the info to
ribosomes
• What are the steps of the central dogma? -✓✓DNA -> RNA -> Protein
• What are genes? -✓✓DNA sequence that carries instructions to make one protein
• What is transcription? -✓✓Process of copying the information in DNA (gene) into
mRNA
• What are the 3 stages of transcription? -✓✓Initiation, elongation, termination
• What is the coding/non-template strand? -✓✓The DNA strand that has the same
sequence as the mRNA produced during transcription (except that thymine (T) in DNA
is replaced by uracil (U) in RNA)
• What is the template/non-coding strand? -✓✓The DNA strand that is complementary
to the RNA molecule being produced (and is read in the 3' to 5' direction, allowing RNA
polymerase to synthesize RNA in the 5' to 3' direction)
