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-Based Technology

General Biology

18. Biotechnology

Introduction to DNA-Based Technology

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Multiple Choice

Why do the two possible PCR products differ in size by 300 base pairs?

The PCR reaction temperature causes one product to denature and reanneal, increasing its size by 300 base pairs.

A mutation in the template DNA causes one product to be 300 base pairs longer.

The DNA polymerase used in the reaction adds 300 extra base pairs to one product.

One of the primers binds to a site 300 base pairs upstream or downstream compared to the other, resulting in a size difference.

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Verified step by step guidance

Understand the concept of PCR (Polymerase Chain Reaction): PCR is a technique used to amplify specific DNA sequences. It requires primers, which are short DNA sequences that bind to the target DNA and define the region to be amplified.

Recognize the role of primers in determining the size of the PCR product: The primers dictate the start and end points of the amplified DNA fragment. If one primer binds to a site upstream or downstream compared to the other, the amplified region will differ in size.

Analyze the scenario described in the problem: The size difference of 300 base pairs is due to one primer binding to a site that is 300 base pairs upstream or downstream relative to the binding site of the other primer.

Rule out incorrect explanations: The temperature of the PCR reaction does not cause a size difference, mutations in the template DNA do not explain the consistent 300 base pair difference, and DNA polymerase does not randomly add extra base pairs to the product.

Conclude that the correct explanation is based on primer binding locations: The difference in size arises because one primer binds to a site that is 300 base pairs away from the binding site of the other primer, resulting in a PCR product that is either longer or shorter by 300 base pairs.