recessive lethal

(adjective)

an inheritance pattern in which an allele is only lethal in the homozygous form and in which the heterozygote may be normal or have some altered non-lethal phenotype

Related Terms

  • dominant lethal
  • mutation

Examples of recessive lethal in the following topics:

  • Lethal Inheritance Patterns

    • An inheritance pattern in which an allele is only lethal in the homozygous form and in which the heterozygote may be normal or have some altered non-lethal phenotype is referred to as recessive lethal.
    • For crosses between heterozygous individuals with a recessive lethal allele that causes death before birth when homozygous, only wild-type homozygotes and heterozygotes would be observed.
    • In other instances, the recessive lethal allele might also exhibit a dominant (but not lethal) phenotype in the heterozygote.
    • For instance, the recessive lethal Curly allele in Drosophila affects wing shape in the heterozygote form, but is lethal in the homozygote.
    • However, just as the recessive lethal allele might not immediately manifest the phenotype of death, dominant lethal alleles also might not be expressed until adulthood.
  • Genetic Variation

    • This low genetic diversity means they are often susceptible to disease and often pass on lethal recessive mutations; only about 5% of cheetahs survive to adulthood.
  • Recessions

    • A recession is a business cycle contraction; a general slowdown in economic activity.
    • In economics, a recession is a business cycle contraction; a general slowdown in economic activity.
    • When these relationships become imbalanced, recession can develop within a country or create pressure for recession in another country.
    • Most mainstream economists believe that recessions are caused by inadequate aggregate demand in the economy, and favor the use of expansionary macroeconomic policy during recessions.
    • As an informal shorthand, economists sometimes refer to different recession shapes, such as V-shaped, U-shaped, L-shaped, and W-shaped recessions.
  • Humans and Electric Hazards

    • Shocks range in severity from painful but otherwise harmless to heart-stoppingly lethal.
    • The lethality of an electric shock is dependent on several variables:
    • Current: The higher the current, the more likely it is lethal.
    • Duration: The longer the duration, the more likely it is lethal -- safety switches may limit the time of current flow.
    • Pathway: If current flows through the heart muscle, it is more likely to be lethal.
  • Mendel's Law of Dominance

    • In a heterozygote, the allele which masks the other is referred to as dominant, while the allele that is masked is referred to as recessive.
    • One allele can be dominant to a second allele, recessive to a third allele, and codominant to a fourth.
    • If a genetic trait is recessive, a person needs to inherit two copies of the gene for the trait to be expressed.
    • Thus, both parents have to be carriers of a recessive trait in order for a child to express that trait .
    • Recessive traits are only visible if an individual inherits two copies of the recessive allele
  • The Recession

    • Bush's administration in the early 1990s, the United States entered into a mild recession that lasted for six months.
    • Coming at around the same time as President Bush's budget deal with Congress, the United States entered into a mild recession that lasted for six months.
    • The first burst of the recession was short-lived, as fervent pre-election activity by the governments of the United States and Canada created what many economists at the time saw as an economic miracle: a growing consumer confidence and increased consumer spending almost single-handedly lifted the North American economy out of recession.
    • Bush in the United States may have been aided by the brief recovery of 1988, he could not hold on to power through the last part of the recession.
    • This graph illustrates the GDP growth (at annualized rates) in the United States between 1989 and 1992, showing the 1990-91 recession.
  • Genetic Defects from Radiation

    • Initial stage: the first 1–9 weeks; the period with the greatest number of deaths—90 percent due to thermal injury and/or blast effects and 10 percent due to super-lethal radiation exposure.
    • Intermediate stage: from 10–12 weeks; deaths in this period are from ionizing radiation in the median lethal range.
  • Complementation

    • Complementation refers to a relationship between two different strains of an organism which both have homozygous recessive mutations.
    • Since the mutations are recessive, the offspring will display the wild-type phenotype.
    • If there is an allele with an observable phenotype whose function can be provided by a wild type genotype (i.e., the allele is recessive), one can ask whether the function that was lost because of the recessive allele can be provided by another mutant genotype.
    • Because the mutations are recessive, there is a recovery of function in that pathway, so offspring recover the wild-type phenotype.
    • Thus, the test is used to decide if two independently derived recessive mutant phenotypes are caused by mutations in the same gene or in two different genes.
  • Arguments For and Against Fighting Recession with Expansionary Fiscal Policy

    • Expansionary fiscal policies, which are usually implemented during recessions, attempt to increase economic demand.
    • Expansionary fiscal policies are usually implemented during recessions because they attempt to increase economic demand, and as a result, increase economic output which is reduced during a recession.
    • Evaluate the pros and cons of fiscal policy intervention during recession
  • Peacetime Economy

    • The postwar transition to a peacetime economy saw strikes and a recession, but the economy fared much better than expected.
    • The decline in government spending, at the end of World War II in 1945, led to an enormous drop in gross domestic product, making this technically a recession.
    • The post-war years were unusual in a number of ways, unemployment was never high, and this era may be considered a "sui generis end-of-the-war recession," or a very unique type of recession.
    • Three years later, the 1948 recession became a brief economic downturn.
    • Although no recession of the post-World War II era has come anywhere near the depth of the Great Depression, this graph shows that the recession during the transition to a peacetime economy during the Truman administration was significant.
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