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

18. Biotechnology

Introduction to DNA Cloning

General Biology

18. Biotechnology

Introduction to DNA Cloning

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1:10 minutes

Problem 6

Textbook Question

Which of the following is not true of cDNA produced using human brain tissue as the starting material?
a. It can be amplified by the polymerase chain reaction.
b. It was produced from pre-mRNA using reverse transcriptase.
c. It can be labeled and used as a probe to detect genes expressed in the brain.
d. It lacks the introns of the pre-mRNA.

Verified step by step guidance

Understand what cDNA is: cDNA, or complementary DNA, is synthesized from an mRNA template using the enzyme reverse transcriptase. This process involves converting the RNA sequence into a DNA sequence.

Consider the role of reverse transcriptase: Reverse transcriptase is an enzyme that synthesizes cDNA from an RNA template. This means that cDNA is derived from mature mRNA, which does not contain introns, as introns are removed during RNA processing.

Evaluate option a: cDNA can indeed be amplified by the polymerase chain reaction (PCR) because it is a DNA sequence, and PCR is a technique used to amplify DNA.

Evaluate option b: cDNA is produced from mature mRNA, not pre-mRNA. Pre-mRNA contains introns, which are spliced out to form mature mRNA before reverse transcription occurs.

Evaluate option c and d: cDNA can be labeled and used as a probe to detect gene expression, and it lacks introns because it is synthesized from mature mRNA. Therefore, option b is not true because cDNA is not produced from pre-mRNA.

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Key Concepts

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

cDNA and Reverse Transcriptase

cDNA, or complementary DNA, is synthesized from an mRNA template using the enzyme reverse transcriptase. This process involves converting the single-stranded RNA into double-stranded DNA, which is crucial for studying gene expression. cDNA lacks introns because it is derived from processed mRNA, which has already undergone splicing to remove introns.

Polymerase Chain Reaction (PCR)

The polymerase chain reaction (PCR) is a technique used to amplify specific DNA sequences, making millions of copies from a small initial sample. This method is essential for analyzing small amounts of DNA, such as cDNA, allowing for further study or use in various applications like cloning or sequencing. PCR requires primers, nucleotides, and a DNA polymerase enzyme to replicate the target DNA.

Gene Expression and Probes

Gene expression refers to the process by which information from a gene is used to synthesize functional gene products like proteins. cDNA can be labeled with radioactive or fluorescent tags to serve as probes, which are used to detect specific gene sequences in various samples. This technique helps identify which genes are active in particular tissues, such as the brain, by hybridizing the labeled cDNA to complementary sequences.