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Questions and Answers
What is the primary purpose of biotechnology?
Which step in biotechnology involves the use of restriction enzymes?
What is a major risk associated with the CRISPR gene-editing technology?
Which of the following describes recombinant DNA technology?
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What is a potential concern regarding genetically modified organisms (GMOs)?
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What distinguishes a dominant trait from a recessive trait?
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Which type of selection would favor individuals at both extremes of a trait?
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What part of Darwin's theory contributed to the understanding of shared characteristics among species?
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What is the primary challenge associated with gene therapy?
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Which of the following is NOT a characteristic of DNA fingerprinting?
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In a test-cross, which type of individual is used to determine the genotype of an unknown organism?
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What is a characteristic feature of polygenic traits?
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Which mechanism of evolution describes changes in allele frequencies due to random sampling effects?
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Which of these is NOT a method of genetic testing?
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What does the Law of Segregation state about alleles?
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Study Notes
Biotechnology Definition and Examples
- Biotechnology uses living organisms or their components to make useful products.
- Examples include: genetic engineering, fermentation, vaccine production, and enzyme production.
Important Processes in Biotechnology
- Chop: Restriction enzymes cut DNA at specific sequences.
- Amplify: PCR (Polymerase Chain Reaction) makes multiple copies of DNA.
- Insert: Vectors like plasmids introduce DNA into host cells.
- Grow: Modified organisms are cultured to produce desired products.
CRISPR
- CRISPR is a gene-editing technology that acts like molecular scissors.
- It uses the Cas9 enzyme to cut DNA at specific locations.
- Allows precise modification of genes.
- Risks: Off-target effects (unintended DNA modifications), potential ecological impacts, and ethical concerns about human germline editing.
Agriculture
- Genetic Engineering: Directly manipulating an organism's genes to introduce desired traits.
- Recombinant DNA Technology: Combining DNA from different sources to create organisms with new genetic combinations.
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Factors Driving Modified Crop Adoption:
- Insecticides/Insect Resistance: Crops produce their own pesticides, reducing chemical spraying.
- Herbicide Resistance: Crops tolerate herbicides, allowing better weed control.
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Rewards vs. Risks:
- Transgenic Salmon: Faster growth rate but concerns about ecological impact.
- Featherless Chicken: Easier processing but animal welfare concerns.
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GMO Concerns:
- Environmental impact, gene transfer to wild species, food safety, and biodiversity loss.
Human Health
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Treat vs. Prevent and Cure:
- Treatment: Manage symptoms.
- Prevention: Stop disease before it occurs.
- Cure: Eliminate disease completely.
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Applications:
- Diabetes: Synthetic insulin production.
- Human Growth Hormone: Treatment for growth disorders.
- Gene Therapy: Modifying genes to treat diseases. Poor success due to immune responses, targeting difficulties, and complex genetic diseases.
- Genetic Testing: Parental carrier testing, prenatal diagnosis, and predictive testing for late-onset conditions.
Forensic Science
- Humans share 99.9% of their DNA sequences.
- 0.1% variation makes each person unique.
- STRs (Short Tandem Repeats): Repeated DNA sequences that vary between individuals. Used for identification.
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DNA Fingerprinting:
- Pros: Highly accurate, small sample needed, long-term stability.
- Cons: Cost, privacy concerns, processing time.
Key Definitions
- Heredity: Transmission of traits from parents to offspring.
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Dominant vs. Recessive Traits:
- Dominant: Expressed with only one copy.
- Recessive: Expressed only with two copies.
- Test-cross: Crossing with homozygous recessive to determine genotype.
- Pedigrees: Family trees showing inheritance patterns.
- Incomplete Dominance: Neither allele is completely dominant.
- Codominance: Both alleles are expressed equally.
- Polygenic Traits: Influenced by multiple genes.
- Additive Traits: Genes have a cumulative effect.
- Pleiotropy: One gene affects multiple traits (e.g., Marfan syndrome).
- Phenotypes: Observable characteristics.
- Dihybrid: Cross involving two traits.
- Independent Assortment: Random separation of different gene pairs.
- Linked Genes: Genes close together on the same chromosome.
Mendel's Research
- Critical Features: Pure-breeding plants, controlled breeding, statistical analysis.
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Important Ideas:
- Traits are controlled by factors (genes).
- Factors come in pairs.
- Factors separate during gamete formation.
- Law of Segregation: Allele pairs separate during gamete formation, each gamete receives one allele.
Using Punnett Squares
- Tool for predicting offspring genotypes.
- Shows all possible combinations of gametes.
- Helps calculate the probability of traits.
Darwin's Contributions
- Observed Patterns: Variation within species, fossil evidence, geographic distribution.
- Origin of Species: Common descent, natural selection, gradual change.
Evolution Mechanisms
- Mutations: Random genetic changes, source of new alleles. Can be beneficial, harmful, or neutral.
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Genetic Drift: Random changes in allele frequencies.
- Founder Effect: Small group establishes a new population.
- Bottleneck Effect: Population severely reduced.
- Gene Flow: Movement of genes between populations through migration and interbreeding.
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Natural Selection:
- Conditions: Variation exists, traits are heritable, differential reproduction.
- Fitness Elements: Survival, reproduction, resource acquisition.
- Sexual Selection: Mate choice and competition for mates.
Types of Selection
- Directional: Favors one extreme.
- Stabilizing: Favors intermediate traits.
- Disruptive: Favors both extremes.
Evidence for Evolution
- Fossil Record: Radiometric dating, fossilization, missing links show transitions.
- Biogeography: Geographic distribution of species (Example: Marsupial distribution).
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Comparative Anatomy/Embryology:
- Homologous Structures: Same origin, different functions.
- Vestigial Structures: Reduced, non-functional.
- Convergent Evolution: Similar traits in unrelated species.
- Molecular Biology: DNA/protein similarities and genetic code universality.
- Laboratory/Field Studies: Observable evolution and experimental evidence.
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