Dominant and Recessive Traits in Plants, Animals, and Humans

There are 23 pairs of chromosomes in each human cell and hundreds of thousands of distinct genes on each chromosome.

An individual inherits two versions of each gene, known as alleles, from each parent.

An allele is a chromosomal pair of genes that controls a heritable trait.

Alleles can be categorized as dominant or recessive, where dominant refers to the visible trait, and recessive refers to the one that is not visible morphologically.

Dominant alleles are generally denoted by capital letters, whereas recessive alleles are denoted by lowercase letters.

Dominant and Recessive Traits
Dominant and Recessive Traits

A homozygous trait has either two capital letters or two lowercase letters.

Heterozygous traits are those that have alternating letters. The capital letter will always come first in heterozygous alleles.

For example: 

If the dominant gene for brown eyes is “B” and the recessive gene is “b” for blue eyes, then the alleles for the dominant trait can be either “BB” or “Bb” while “bb” is for a recessive trait.

A person will exhibit the dominant trait if they have a heterozygous set of alleles, i.e., BB or Bb.

In the case of a recessive trait, the alleles of the trait-causing gene are the same, and both recessive alleles must be present to express the trait (bb). 

Having the same two copies of an allele is a homozygous condition.

When only one copy is present, a recessive allele does not result in any trait. 

On the other hand, a dominant trait can also be expressed when one of the two alleles is present.

Many genes interact in the production of one trait, such as hair color, eye color, size, shape, and so forth, and one gene (in conjunction with others) often influences many traits.

Dominant and Recessive Traits in Plants

Name of PlantDominant TraitRecessive Trait
NettleSerrated leavesSmooth margined leaves
SunflowerBranched habitUnbranched habit
CottonColored lintWhite lint
MaizeRound starchy kernelWrinkled sugary kernel
SnapdragonRed flowerNon-red flower
BarleyBeardlessnessBeardness
WheatSusceptibility to rustImmunity to rust
TomatoTwo-celled fruitsMany-celled fruit

Dominant and Recessive Traits in Animals

Name of AnimalBody characterDominant TraitRecessive Trait
CatSkin colorTabbyBlack or Blue
CatLength of hairShort hairLong Hair
DogSkin colorGreyBlack
DogTailStumpyNormal
CattleFace ColorWhiteColored
CattleHornPoled or HornlessHorned
HorseSkin colorBlackRed
HorseMovementTrottingPacing
SheepHair/Wool/FleeceWhiteBlack
SwineSkin colorBlackRed
SwineHoofUncleftNormal
SalamanderBody colorDarklight
DrosophilaEye colorRedWhite
DrosophilaWingsFlat and yellowCurled and White
DrosophilaBody colorGreyBlack
Land snailShape of shellUnbanded shellBanded shell

Dominant and Recessive Traits in Humans

TraitsDominantRecessive
Baldness (In male)PresenceAbsence
Body HairAbundantLittle
Bend Pinkie FingerAble to bendNot able to bend
Cleft in ChinPresenceAbsence
Crossing of ThumbsLeft thumb over right thumbRight thumb over left thumb
DimplesPresenceAbsence
EarlobesFree earlobesAttached earlobes
FrecklesPresenceAbsence
IrisBrownBlue
HairlineWidow’s peakStraight
Hair ColorDarkLight
HandednessRight handednessLeft handedness
Hitchhiker’s ThumbsAbsencePresence
Lips widthBroad lipsThin lips
Mongolian Eye FoldPresenceAbsence
Nose ShapeRoman nose (bump)Straight
Nose WidthBroad noseNarrow nose
Rh factor in BloodRh factor positive (+)Rh factor negative (-)
Toe LengthSecond toe longer than first toeFirst toe longer than second toe
Tongue Rolling Ability to roll tongueInability to roll tongue
Webbed FingersPresenceAbsence

References

  1. Altenburg E. (1965). The Relation of Genes to Traits. In Genetics (Revised Edition). Holt, Rinehart and Winston, Inc., pp. 16
  2. Biologywise. (2022). Dominant and Recessive Traits in Humans. 
  3. Accessed from: https://biologywise.com/dominant-recessive-traits-in-humans. Accessed on: 13.09.2022
  4. Classroom Partners. (2022). Punnett Square.
  5. Accessed from: https://pressbooks.umn.edu/classroompartners/chapter/punnett-squares/. Accessed on: 13.09.2022
  6. National Human Genome Research Institute (NIH). (2022). Recessive Traits and Alleles. Accessed from: https://www.genome.gov/genetics-glossary/Recessive-Traits-Alleles. Accesed on: 13.09.2022.
  7. Verma P.S. and Agarwal V.K. (2005). Mendel and His work. In Cell Biology, Genetics, Molecular Biology, Evolution and Ecology. Multi-color Edition. S. Chand & Company Ltd. Ram Nagar, New Delhi, pg 29-30

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