Terry McGuire: Lead Editor

All Articles Within Gene Inheritance and Transmission (32)

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Gene Mapping (1)

• Gene Mapping: Then and Now
  Model organisms have long been valuable resources for mapping the genes responsible for specific phenotypes. Today, with the help of entire genomic sequences, scientists are equipped with additional tools to help them map genes to chromosomes. How does this work? How has genome sequencing changed the landscape of gene mapping? How do we use model organisms, like zebrafish, to locate specific genes involved in human biology?

The Foundation of Inheritance Studies (11)

• Non-nuclear Genes and Their Inheritance
  Some genes are passed on from parent to offspring without ever being part of a nuclear chromosome. Where are these genes found, and how does this non-nuclear inheritance occur?
• Multifactorial Inheritance and Genetic Disease
  Multifactorial diseases, such as coronary artery disease, can be as complex as their name suggests. How much can we hope to understand about diseases with such variation in inheritance?
• Gregor Mendel and the Principles of Inheritance
  Gregor Mendel's principles of inheritance form the cornerstone of modern genetics. So just what are they?
• Genetic Recombination
  How does DNA recombination work? It occurs frequently in many different cell types, and it has important implications for genomic integrity, evolution, and human disease.
• Mitosis, Meiosis, and Inheritance
  Although mitosis and meiosis both involve cell division, they transmit genetic material in very different ways. What happens when either of these processes goes awry?
• Developing the Chromosome Theory
  Scientists were able to identify chromosomes under the microscope as early as the 19th century. But what did it take for them to figure out how important chromosomes really are?
• Test Crosses
  When you see a dominant trait, the underlying genetic make-up can still be ambiguous. See how researchers use test crosses to find out the genotype behind the phenotype.
• Sex Chromosomes and Sex Determination
  In humans and many other animals, specific chromosomes determine sex. But how did researchers discover these so-called sex chromosomes?
• Mendelian Genetics: Patterns of Inheritance and Single-Gene Disorders
  What can Gregor Mendel’s pea plants tell us about human disease? Single gene disorders, like Huntington’s disease and cystic fibrosis, actually follow Mendelian inheritance patterns.
• Sex determination in honeybees
  In humans, sex is determined by the presence or absence of X or Y sex chromosomes. In honeybees, however, evolution has resulted in a very different and unique sex determination system.
• Polygenic Inheritance and Gene Mapping
  Ever griped about your height? Figuring out its origins hasn't been any easier for geneticists who are turning to high-throughput, genome-wide association studies for clues.

Gene Linkage (5)

• Thomas Hunt Morgan and Sex Linkage
  Can paying attention establish a new field? Learn about Thomas Hunt Morgan, the first person to definitively link trait inheritance to a specific chromosome and his white-eyed flies.
• Chromosome Theory and the Castle and Morgan Debate
  Scientific debates can be as passionate and high-profile as political ones. Learn about an epic battle waged between the Castle and Morgan laboratories over the organization of genes.
• Thomas Hunt Morgan, Genetic Recombination, and Gene Mapping
  How would you feel if you had to be the one to challenge Gregor Mendel's paradigm-shifting laws of inheritance? Yet Thomas Hunt Morgan did exactly this and in the process made gene mapping possible.
• Discovery and Types of Genetic Linkage
  Soon after the rediscovery of Mendel's work, several scientists noted traits in their crosses seemed “coupled.” But this deviated from Mendel's principles, so how did they explain this?
• Genetics and Statistical Analysis
  "Significance" has a very particular meaning in biology thanks to statistics. How does this term prove an experiment's results are worth special attention?

Variation in Gene Expression (6)

• Pleiotropy: One Gene Can Affect Multiple Traits
  How can a mutation in one single gene cause a disease with a wide range of symptoms? This situation is referred to as pleitropy, and it has been identified in a wide range of species, even humans.
• Phenotype Variability: Penetrance and Expressivity
  Sometimes, identical genes will produce different expression patterns. Why? Geneticists are now examining the "penetrance" and "expressivity" of genotypes and their phenotypes.
• Genetic Dominance: Genotype-Phenotype Relationships
  Why can you possess traits neither of your parents have? The relationship of genotype to phenotype is rarely as simple as the dominant and recessive patterns described by Mendel.
• Environmental Influences on Gene Expression
  Internal and external environmental factors, like gender and temperature, influence gene expression.
• Phenotypic Range of Gene Expression: Environmental Influence
  Obviously, genes are not the only factors that determine phenotype—after all, even identical twins are not exactly alike. But what can armadillos teach us about being an individual?
• Epistasis: Gene Interaction and Phenotype Effects
  Epistasis describes how gene interactions can affect phenotypes. Did you know that genes can mask each other’s presence or combine to produce an entirely new trait?

Methods for Studying Inheritance Patterns (7)

• Mapping Genes to Chromosomes: Linkage and Genetic Screens
  After the invention of whole-genome sequencing, we now know the sequences that make up an entire organism. Now what do they mean? To answer that, we turn back to linkage mapping in model organisms.
• Paternity Testing: Blood Types and DNA
  The modern-day paternity test compares a baby’s DNA profile to the potential father’s. How did we ever manage it before genetics?
• Mendelian Ratios and Lethal Genes
  What happens when good genes go bad? What kinds of mutations create "lethal genes," and how are they passed on?
• Biological Complexity and Integrative Levels of Organization
  If someone gave you a stranger’s complete genetic code, could you predict everything about that person? Of course not, but why isn't there one code to explain how everything works?
• Human Evolutionary Tree
  Researchers have used distinct markers from human subpopulations to trace back to our common African root in a giant human "tree." However, a “trellis” model might be more appropriate.
• C. elegans: Model Organism in the Discovery of PKD
  What does the sex of worms have to do with human kidneys? See how C. elegans research has unlocked scientists' understanding of polycystic kidney disease.
• Genetics of Dog Breeding
  How did your friendly Fido become so different from his closest living relative, the wolf? See what scientists believe about humans' artificial selection pressures on the dog genome.