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

DNA Fingerprinting

General Biology

18. Biotechnology

DNA Fingerprinting

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1:20 minutes

Problem 3

Textbook Question

The DNA profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a DNA profile shows
a. The order of bases in a particular gene.
b. The presence of various-sized fragments of DNA.
c. The presence of dominant or recessive alleles for particular traits.
d. The order of genes along particular chromosomes.

Verified step by step guidance

Understand the context of DNA profiling: DNA profiles are created using a technique called gel electrophoresis, which separates DNA fragments based on their size. This is a key concept to keep in mind when analyzing the options.

Recall that DNA fragments are generated by cutting DNA with restriction enzymes. These enzymes recognize specific sequences in the DNA and cut at those sites, producing fragments of varying lengths.

In gel electrophoresis, these DNA fragments are loaded into a gel and subjected to an electric current. Smaller fragments move faster and farther through the gel, while larger fragments move more slowly. This creates a pattern of bands that is unique to an individual.

Analyze the options: The pattern of bars in a DNA profile does not directly show the order of bases in a gene (option a), the presence of dominant or recessive alleles (option c), or the order of genes along chromosomes (option d). Instead, it reflects the presence of DNA fragments of different sizes (option b).

Conclude that the correct answer is based on the principle that DNA profiles represent the presence of various-sized fragments of DNA, as determined by gel electrophoresis.

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Key Concepts

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

DNA Profiling

DNA profiling is a forensic technique used to identify individuals based on their unique DNA characteristics. It involves analyzing specific regions of DNA that vary greatly among individuals, resulting in a pattern that can be visualized similarly to a barcode. This method is crucial in criminal investigations as it can link a suspect to a crime scene or exonerate innocent individuals.

Restriction Fragment Length Polymorphism (RFLP)

RFLP is a technique used in DNA profiling that involves cutting DNA into fragments with restriction enzymes. The resulting fragments vary in size due to differences in the DNA sequence among individuals. These size variations are then separated by gel electrophoresis, creating a distinct pattern that can be compared between samples, much like a barcode.

Alleles and Genetic Variation

Alleles are different versions of a gene that can exist at a specific locus on a chromosome. The combination of alleles an individual possesses contributes to their genetic makeup and can influence traits. In DNA profiling, the presence of various alleles can lead to differences in fragment sizes, which are critical for distinguishing between individuals in forensic analysis.

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Related Practice

Multiple Choice

The gel below shows a region of STRs from a DNA sample taken from a crime scene. It also shows the same region of STRs from 4 suspects involved in the case. Which suspect' DNA was found at the crime scene?

Genetic profiles are used to determine whether Sam could be the father of Becky's baby. Sam is not the father if __________ genetic profile shows some bands not present in __________ genetic profile.

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Multiple Choice

Genetic profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a genetic profile shows __________.

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Textbook Question

Imagine you have found a small quantity of DNA. Fill in the following diagram, which outlines a series of DNA technology experiments you could perform to study this DNA.

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Textbook Question

A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). To compare a specific region of the DNA from a sample with DNA from living birds, which of the following would be most useful for increasing the amount of dodo DNA available for testing?

a. SNP analysis

b. Polymerase chain reaction (PCR)

c. Electroporation

d. Gel electrophoresis

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Textbook Question

Why does DNA profiling rely on comparing specific genetic markers rather than the entire genome?

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Textbook Question

A friend who works in a research lab performed a GWAS and discovered a tight association between a SNP allele and the disease she is studying. She concluded that the SNP allele must be the mutation that causes the disease. Explain why she is likely to be wrong.