Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 40m
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 20m
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 52m
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 57m
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

18. Biotechnology

Introduction to DNA Cloning

General Biology

18. Biotechnology

Introduction to DNA Cloning

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1:48 minutes

Problem 2`

Textbook Question

Which of the following is true of a codon?
a. It never codes for the same amino acid as another codon.
b. It can code for more than one amino acid.
c. It can be either in DNA or in RNA
d. It is the basic unit of protein structure

Verified step by step guidance

Understand the definition of a codon: A codon is a sequence of three nucleotides in RNA that corresponds to a specific amino acid or a stop signal during protein synthesis.

Recall that codons are found in messenger RNA (mRNA) and are read during the process of translation to assemble amino acids into a polypeptide chain.

Analyze option (A): This is incorrect because multiple codons can code for the same amino acid due to the redundancy of the genetic code (e.g., both UUU and UUC code for phenylalanine).

Analyze option (B): This is incorrect because each codon specifies only one amino acid or a stop signal; codons do not code for multiple amino acids.

Analyze option (C): This is incorrect because codons are specifically found in RNA, not DNA. DNA contains triplets, which are transcribed into codons in RNA.

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Key Concepts

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

Codon Definition

A codon is a sequence of three nucleotides in DNA or RNA that corresponds to a specific amino acid or a stop signal during protein synthesis. Codons are essential for translating genetic information into proteins, as they dictate the order in which amino acids are assembled.

Genetic Code

The genetic code is the set of rules by which information encoded in genetic material is translated into proteins. It is nearly universal among organisms and consists of 64 codons that specify 20 amino acids, allowing for redundancy where multiple codons can code for the same amino acid.

Difference Between DNA and RNA Codons

Codons can be found in both DNA and RNA, but they play different roles in the two types of nucleic acids. In DNA, codons are transcribed into mRNA, which then carries the genetic information to ribosomes for translation into proteins. This distinction is crucial for understanding the flow of genetic information.