Question

bio1115 exam #3
name:_____________________ date:___________
total points: 100 time: 15 - 20 minutes
section 1: dna structure & gene function
multiple choice questions (1 point each):

1. which of the following is a correct base pairing in dna?

• a. a - g
• b. c - t
• c. a - t
• d. g - t

1. what holds the two strands of dna together?

• a. ionic bonds
• b. hydrogen bonds
• c. covalent bonds
• d. peptide bonds

1. which enzyme is responsible for transcription?

• a. dna polymerase
• b. rna polymerase
• c. ligase
• d. helicase

1. where does transcription occur in the cell?

• a. cytoplasm
• b. ribosome
• c. nucleus
• d. mitochondria

1. what is the central dogma of molecular biology?

• a. dna → protein → rna
• b. rna → dna → protein
• c. dna → rna → protein
• d. protein → rna → dna

1. which of the following is a nitrogenous base in dna?

Explanation:

1. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). So, A - T is correct.
2. Hydrogen bonds hold the two strands of DNA together. Ionic bonds involve transfer of electrons, covalent bonds are strong bonds within a molecule, and peptide bonds are in proteins.
3. RNA polymerase is responsible for transcription (synthesis of RNA from DNA template). DNA polymerase is for DNA replication, ligase joins DNA fragments, and helicase unwinds DNA.
4. Transcription occurs in the nucleus (in eukaryotes) as DNA is mainly located there. Cytoplasm has other functions, ribosome is for translation, and mitochondria are for energy production.
5. The central dogma of molecular biology is DNA → RNA → Protein. DNA is transcribed to RNA which is translated to protein.

Answer:

1. C. A - T
2. B. Hydrogen bonds
3. B. RNA polymerase
4. C. Nucleus
5. C. DNA → RNA → Protein