Molecular biologyLesson 2 of 4 in the course Biochemistry of the Genome

DNA Structure, Strand Organization, and Cellular Roles

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

DNA carries hereditary information in the order of its nucleotides. In this lesson, we examine the parts of a DNA nucleotide and how nucleotides link to form a strand.

The carbons in deoxyribose are numbered 1′ through 5′. The prime symbol distinguishes sugar-carbon numbers from positions in the nitrogenous base. A nucleoside consists of the sugar and base only; adding one or more phosphate groups makes it a nucleotide.

All flashcards

What is a deoxyribonucleotide?
A DNA building block composed of deoxyribose, a phosphate group, and a nitrogenous base.
What does it mean for DNA strands to be antiparallel?
The strands run in opposite chemical directions: one 5′ to 3′ and the other 3′ to 5′.
What are the DNA base-pairing rules?
Adenine pairs with thymine, and cytosine pairs with guanine.
What is DNA denaturation?
Separation of double-stranded DNA into single strands when conditions disrupt hydrogen bonds between bases.
How does GC content affect DNA denaturation?
DNA with higher GC content generally requires more energy to denature because C–G pairs have three hydrogen bonds.

Quiz questions

  1. What does it mean for the two strands of DNA to be antiparallel?Answer: They run in opposite chemical directions.
  2. Which relationship describes Chargaff’s rules for double-stranded DNA?Answer: Adenine is approximately equal to thymine, and cytosine to guanine.
  3. How are the components arranged in the DNA double helix?Answer: Sugar-phosphate backbones are outside, and paired bases are inside.
  4. What happens to DNA during denaturation?Answer: The strands separate as hydrogen bonds between complementary bases are disrupted.
  5. What is vertical gene transfer?Answer: Transmission of genetic information from a parent cell to its descendants.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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