Genetics and Biotechnology Final Review
Historical Pioneers and Figures in Genetics and Evolutionary Biology
Willard Libby: Recognized for the invention of Radioactive dating.
Charles Lydell: Associated with the Theory of Evolution alongside Charles Darwin.
Georges Cuvier: Renowned as a great comparative anatomist of fossils.
Ernst Mayr: Provided the modern definition of species.
Calvin Bridges: Studied sex determination specifically in fruit flies.
Nettie Stevens: Credited with the discovery of sex chromosomes in insects.
Earnest Haeckel: Famous for the phrase "Ontogeny recapitulates Phylogeny."
Thomas Hunt Morgan: The founder of the Columbus Fly room; conducted seminal work on fruit fly genetics.
Russel Wallace: A geologist whose work inspired Charles Darwin's evolutionary theories.
Herman Muller: Discovered that X-Rays cause gene mutations.
Hugo deVire: One of the scientists who rediscovered Gregor Mendel's work in .
Theodor Boveri: Used sea urchins to postulate that cancer cells could derive from abnormalities of the chromosomes.
Craig Venter: Helped sequence the human genome and advanced whole genome sequencing technology.
Walter Gilbert: Developed important DNA sequencing methods and contributed to molecular biology research.
Hamilton Smith: Discovered restriction enzymes used in genetic engineering and biotechnology.
Herbert Boyer: Pioneer of recombinant DNA technology and co-founder of Genentech.
Kary Mullis: Invented the Polymerase Chain Reaction (), which amplifies DNA for testing and research; won the Nobel Prize.
Stanley Cohen: Collaborated with Boyer; demonstrated that DNA could be cut and inserted into plasmids, leading to the first successful gene cloning.
Paul Berg: Early researcher in recombinant DNA; organized the Asilomar Conference () to address safety and ethics.
Werner Arber: Discovered restriction enzymes, allowing DNA to be cut at specific sites.
Frederick Sanger: Developed the Sanger sequencing method, the first method to read DNA sequences.
Svante Pääbo: Sequenced the Neanderthal genome, providing insights into human evolution.
Jennifer Doudna & Emmanuelle Charpentier: Developed gene editing technology; won the Nobel Prize in .
Fundamental Principles of Genetics and Inheritance
Species Definition: A group of interbreeding, genetically compatible natural populations that are isolated from other such groups; capable of producing fertile offspring.
Victorian - Uniformitarianism: A conceptual framework mentioned in the context of evolutionary history.
The Chromosome Theory of Inheritance: Implies that Mendel’s postulated units of inheritance are located on chromosomes.
August Weissman’s Mouse Experiment: Showed that acquired traits are not inherited, contradicting earlier theories like Lamarckism.
Genetic Fitness: A couple with children is said to have lower genetic fitness compared to a couple with children.
Genetic Linkage: Occurs when genes are located close together on the same chromosome.
Mendelian Ratios: If Mendel had crossed the generation tall plants (obtained from tall and short parents) back to the short parental plants, he should have obtained tall and short plants in a ratio of tall to short.
Sex-Linked Inheritance in Fruit Flies: * Initial work by Thomas Hunt Morgan showed that crossing a male white-eyed fruit fly with a female red-eyed fly yielded all red-eyed flies in the generation. * Crossing the generation to themselves resulted in all red-eyed females, while half the males had white eyes and the other half had red eyes.
Human Parallels to Fruit Fly Inheritance: The same inheritance pattern seen in white-eyed fruit flies is observed in humans with the disorder Hemophilia.
Continuous Variation: Traits like height and do not follow simple Mendelian Dominant/Recessive inheritance; instead, they follow a "bell-shaped continuous" distribution.
Sex Determination in Humans: * The default phenotype is female if the gene is deleted.
Anticipation: A situation where a genetic disease has even more serious clinical manifestations in successive generations.
Heterozygote Advantage: A relationship often associated with Malaria and Sickle Cell Anemia.
Comparative Primate Biology and Social Structures
Orangutans: * Basic Unit: Live in packs. * Female Biology: Possess an Estrous Cycle (periods of sexual receptivity). * Male Investment: Males contribute sperm and then leave the group ("walk").
Chimpanzees: * Basic Unit: Live in groups. * Sexual Strategy: Promiscuous; multiple males copulate with an estrous female. * Paternal Investment: Minimal effort in rearing "troop infants."
Gorillas: * Basic Unit: Harem-like organization. * Leadership: An Alpha Male copulates with multiple estrous females. * Labor Division: Child rearing is a female occupation; the Alpha male focuses on fighting off rival males.
Gibbons: * Basic Unit: Small, scattered populations. * Sexual Strategy: Form couples and exhibit shared child-rearing responsibility.
Summary of Observed Primate Patterns: * Monogamous couples. * Promiscuity (both male and female). * Harems led by an Alpha male. * "Deadbeat" or "walk-away" male behavior. * Both heterosexual and homosexual behaviors.
The Nature and Chemistry of Mating
Helen Fisher: Rutgers Anthropologist and author of Why We Love: The Nature and Chemistry of Romantic Love.
Core Brain Systems for Mating: 1. Lust: The sex drive or libido; evolved to initiate mating with various partners. 2. Attraction: Early-stage intense romantic love; evolved to focus mating energy on one partner at a time. 3. Attachment: Deep feelings of union; evolved to enable pair bonding and cooperative child rearing.
Prenatal Hormones: Studies in rats and mice show that exposing female fetuses to high levels of exogenous testosterone during critical brain development leads to male mating behavior as adults.
Sex reassignment and The Case of David Reimer
John Money (Johns Hopkins): Argued that gender was learned rather than biological.
The Incident (): After a botched circumcision, David Reimer was reassigned as a female named "Brenda."
Medical Intervention: Surgical orchidectomy was performed at .
Outcome: Though Money reported the case as a success, it was a failure. Reimer eventually reassumed a male identity.
Tragedy: David's twin brother Brian (schizophrenic) committed suicide in ; David committed suicide in . Reimer's parents blamed Money's methodology.
Transsexuality and Gender Identity
Definition: Identifying as the gender opposite to birth sex.
Notable Examples: * Bruce/Caitlyn Jenner. * Dr. Rachel Levine: Reached the rank of Admiral and served as a high-ranking official after serving as the Pennsylvania Secretary of Health.
Human Origins and Paleoanthropology
Forms of Scientific Evidence: 1. Fossil Remains: Physical skeletal and dental evidence. 2. Radioactive Dating: Use of isotropic decay to date fossils and archaeological layers. 3. Genetic Evidence: Study of Mitochondrial DNA () and chromosomes from indigenous, isolated populations.
Australopithecus afarensis ("Lucy"): * Age: Approximately million years old. * Discovery: Found in at Hadar, Ethiopia. * Temporal Range: Species existed from to million years ago. * Traits: Bipedal (human-like pelvis/legs); apelike face (low forehead, bony ridge over eyes, flat nose, no chin). * Dentition: Protruding jaws with large back teeth (teeth were more humanlike than the skull). * Cranial Capacity: to . * Sexual Dimorphism: Females approx. ; males approx. . * Diet: Likely vegetarian (fruits, seeds, soft roots).
Homo erectus: * Migration: First hominid species to migrate out of Africa. * Geography: Colonized Asia ("Beijing Man," "Java Man") and Europe. * Temporal Range: Lived from about million years ago. * Anatomy: Taller stature; brain averaging ; sexual dimorphism similar to modern humans. * Ancestry: Common ancestor of Neanderthals, Homo denisovan, Homo floresiensis, and Homo sapiens.
Homo neanderthalensis (European Hominids): * Range: Inhabited Europe from approx. to years ago. * Brains: As large as modern humans, but shaped differently. * Physique: Heavily built; larger nose; larger/broader rib cage; shorter forearm and tibia; broader hips.
Hypotheses for Modern Human Origins: 1. Multiregional Hypothesis: Modern humans evolved in parallel from local populations; occasional interbreeding explains similarity; last common ancestor in Africa over million years ago. 2. "Out of Africa" (Replacement) Hypothesis: All evolved from a second migration out of Africa approx. years ago, replacing all regional populations derived from the first migration.
Biotechnology Industry and Tools
Restriction Enzymes: Bacterial enzymes that defend against viral attacks; crucial for the development of sequencing and the biotech industry.
DNA Ligase: Enzyme that unites or joins DNA fragments together.
Vectors: Vehicles like plasmids (e.g., ) and viruses used to carry and transfer DNA.
Gene Cloning: The amplification of a specific gene sequence in bacteria to produce a significant amount of DNA for study.
Polymerase Chain Reaction (PCR): Rapidly generates millions of copies of DNA; uses Taq DNA polymerase.
Sanger Sequencing: Uses dideoxide trinucleotides to determine nucleotide sequences.
CRISPR Technology: Advanced gene editing tool used for precise DNA modifications (e.g., creating animals similar to the extinct Dire Wolf via gene cloning).
Bioreactors: Genetically modified animals containing an incorporated gene to produce pharmaceutical products.
Evolution of Science Stage: Transition from "analysis to synthesis" when a science can predict experimental outcomes to create new products.
Active Site: The place within an enzyme where chemical bonds are created or broken; enzymes generally increase the rate of reaction.
Industry Milestone: Genentech was the first company to produce a successful commercial pharmaceutical product (e.g., insulin).
Genetic Disorders and Characteristics
Cystic Fibrosis (B): Recessive trait; characterized by excessive thick mucus in the lining of the airways, pancreas, and other ducts.
Huntington’s Disease (A): Dominantly inherited; characterized by excessive triplet nucleotide repeats at the beginning of the gene.
Marfan’s Disease (A): Dominantly inherited; shows abnormal body proportions, heart disease, and dislocation of the eye lens.
Achondroplasia: Dominantly inherited; caused by a mutation in the gene; results in bone growth abnormalities.
Sickle Cell Anemia: Recessive disorder affecting hemoglobin; associated with heterozygote advantage against Malaria (which requires reproduction in the human liver and red blood cells).
Duchenne Muscular Dystrophy: -linked recessive disorder causing muscle degeneration.
Mitochondrial Inheritance: A situation where the disease is only inherited from the Mother and can affect both sons and daughters.
Autosomal Recessive Pedigrees: Consanguineous (related by blood) marriages are most often observed in these pedigrees.
Biotechnology Matching and Metrics
Human Genome DNA content: Billion Base Pairs.
Biomedical application of Biotechnology: Hemopoietic stem cell gene editing.
Forensic application of Biotechnology: Identity testing (e.g., DNA fingerprinting).
Asilomar California Meeting: Established genetic engineering regulations.
Multifactorial Genetics: Associated with most common diseases (cancer, diabetes, obesity).
Important restriction enzyme: .
Useful cloning vector: .
Reproductive Cloning: Nuclear transplants.
Tissue Culture: Growing cells outside the body.
Modern Genetic Techniques and Ethics
Human Genome Project: International team worked from to ; sequenced billion base pairs and identified approx. genes.
Testing Types: * Newborn screening (early detection). * Prenatal testing (assessing fetus). * Carrier screening (identifying mutated gene carriers). * Preimplantation genetic diagnosis (testing embryos in ).
Modern Techniques: Whole genome sequencing, gene panels, and microarrays (simultaneous gene expression analysis).
Ethical Concerns: "New Eugenics" regarding genetic selection and equitable access to technology.