Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

15. Gene Expression

Introduction to Transcription

General Biology

15. Gene Expression

Introduction to Transcription

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0:47 minutes

Problem 3

Textbook Question

DNA's primary structure is made up of just four different bases, and its secondary structure is regular and highly stable. How can a molecule with these characteristics hold the information required to build and maintain a cell?

Verified step by step guidance

Understand that DNA's primary structure consists of a sequence of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases are arranged in a specific order along the DNA strand, and this sequence encodes genetic information.

Recognize that the secondary structure of DNA is a double helix, where two complementary strands are held together by hydrogen bonds between specific base pairs: adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G). This complementary base pairing ensures accurate replication and stability of the genetic information.

Realize that the sequence of bases in DNA acts as a code, where groups of three bases (called codons) correspond to specific amino acids. These amino acids are the building blocks of proteins, which perform essential functions in the cell.

Understand that the information in DNA is transcribed into messenger RNA (mRNA) through a process called transcription. The mRNA then carries this information to ribosomes, where it is translated into proteins during the process of translation.

Appreciate that the stability of DNA's secondary structure ensures the long-term storage of genetic information, while the variability in the sequence of bases allows for the diversity of proteins and cellular functions necessary to build and maintain a cell.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

DNA Structure

DNA is composed of a backbone made of sugar and phosphate groups, with four nitrogenous bases (adenine, thymine, cytosine, and guanine) attached. The sequence of these bases encodes genetic information, with specific combinations corresponding to different genes. The primary structure refers to the linear sequence of these bases, while the secondary structure describes the double helix formed by base pairing.

Base Pairing and Complementarity

The stability of the DNA double helix arises from specific base pairing: adenine pairs with thymine, and cytosine pairs with guanine. This complementarity ensures accurate replication and transcription of genetic information. The hydrogen bonds between paired bases contribute to the overall stability of the DNA structure, allowing it to maintain its integrity while still being accessible for cellular processes.

Genetic Code and Protein Synthesis

The genetic code is a set of rules that defines how sequences of nucleotide bases in DNA correspond to amino acids in proteins. This code is read in triplets, known as codons, during the processes of transcription and translation. The information encoded in DNA ultimately directs the synthesis of proteins, which are essential for cell structure and function, thereby enabling the cell to build and maintain itself.