incomplete dominance
LowTechnical/Scientific
Definition
Meaning
A genetic condition where neither of two alleles for a gene is completely dominant over the other, resulting in an intermediate phenotype in heterozygotes.
More broadly, can metaphorically describe any situation where no single factor, trait, or influence fully prevails, leading to a blended or intermediate state.
Linguistics
Semantic Notes
The term is specific to genetics and is not used figuratively in general English, though its components ('incomplete', 'dominance') are common.
Dialectal Variation
British vs American Usage
Differences
No lexical or spelling differences exist. Usage is identical across scientific communities.
Connotations
Purely denotative; carries no additional cultural or connotative differences between regions.
Frequency
Exclusively used in academic or educational contexts related to biology/genetics; extremely rare outside these fields in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
[Gene/Trait] exhibits incomplete dominance.Incomplete dominance occurs when...The phenomenon of incomplete dominance...This is a classic case of incomplete dominance.Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Academic
Primary context. Used in biology textbooks, research papers, and lectures to describe non-Mendelian inheritance patterns.
Everyday
Virtually never used.
Technical
Exclusively used in genetics, biotechnology, and related life science fields.
Examples
By Part of Speech
verb
British English
- The allele for red flower colour incompletely dominates over the allele for white.
- This gene does not completely dominate in the heterozygous condition.
American English
- The red allele incompletely dominates the white allele.
- The trait demonstrates a pattern where neither allele fully dominates.
Examples
By CEFR Level
- In some flowers, red and white alleles mix to make pink. This is called incomplete dominance.
- Our biology teacher showed us a picture of a pink flower from a red and white parent plant as an example of incomplete dominance.
- Unlike Mendel's peas, where one trait was dominant, snapdragons exhibit incomplete dominance, resulting in a third, blended phenotype.
- The geneticist explained that the intermediate height of the hybrid plants was due to incomplete dominance of the height gene.
- The research paper postulated that the quantitative variation in the enzyme's activity could be attributed to a mechanism resembling incomplete dominance at the molecular level.
- Distinguishing between codominance and incomplete dominance requires precise phenotypic analysis at the biochemical or cellular level.
Learning
Memory Aids
Mnemonic
Imagine two painters (alleles) mixing their colours (traits) on a canvas. Neither colour fully covers the other; instead, they create a new, blended colour (phenotype). This is 'incomplete' dominance.
Conceptual Metaphor
GENETIC INHERITANCE IS A BLENDING OF TRAITS (where neither parent trait fully 'wins').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating as 'неполное *господство*', which implies political/social control.
- Correct biological term is 'неполное доминирование'.
Common Mistakes
- Confusing it with 'codominance' (where both alleles are fully expressed, not blended).
- Using it as a general synonym for 'partial control' outside genetics.
- Misspelling as 'incomplete dominence'.
Practice
Quiz
What is the key difference between incomplete dominance and codominance?
FAQ
Frequently Asked Questions
It is a modern genetic concept that describes a similar outcome to the historical idea of 'blending inheritance', but with the crucial difference that the alleles themselves remain distinct and can be separated in future generations.
True, classic examples in humans are rare. Sometimes traits like hair texture (curly vs straight producing wavy) or sickle cell trait (where carriers have a mix of normal and sickle-shaped cells under low oxygen) are cited as analogous, though the latter is often more precisely classified as codominance.
You use the same method as for complete dominance, but the heterozygous genotype (e.g., Rr) produces a distinct phenotype (e.g., pink) different from either homozygous genotype (RR = red, rr = white). The phenotypic and genotypic ratios in the F2 generation are the same (1:2:1).
It demonstrates that dominance relationships are not always absolute, expanding the simple Mendelian model. It helps explain continuous variation in traits and is foundational for understanding more complex quantitative genetics.