Genes are tiny particles that contain genetic material (DNA, dioxyribonucleic acid) and produce proteins responsible for determining and transmitting hereditary characters.
In this way, genes can express distinct genetic categories. For example, dominant traits, expressed by homozygous (AA) and heterozygous (Aa) beings, and recessive traits found only in homozygous (aa).
allele genes
Allele genes are segments of DNA (deoxyribonucleic acid) made up of pairs. One of them comes from the mother (egg) and the other from the father (sperm), which are at the same locus on the homologous chromosomes. They are classified into:
- Recessive Allele Genes: represented by lowercase letters (aa, bb, vv) where the phenotypes are expressed only in homozygosis
- Dominant Allele Genes: represented by capital letters (AA, BB, VV) and expressed phenotypically in heterozygosis.
When the allele genes are the same, it is called "homozygous" and when different, "heterozygotes".
dominant genes
You dominant genes are those that determine a hereditary characteristic even when in a single dose in the genotype. That is, they determine their character even in the absence of their dominant allele.
They are classified into:
- Dominant Homozygote (pure), represented by the capital letters, AA, BB, VV.
- Heterozygous Dominant (hybrid) expressed by an uppercase and lowercase letter Aa, Bb, Vv.
Dominant Characteristics
Some features expressed in the dominant allele genes:
- aquiline nose
- Dislocated earlobe
- Dimpled chin and prognathus
- Thick lips
- Dark hair
- Baldness
- Dark eyes
- Ability to roll the tongue
- curved little finger
- curved thumb
Dominant Gene-Related Diseases
Some diseases related to dominant allele genes:
- polydactyly
- Huntington's Disease
- von Hippel's disease
Recessive Genes
You recessive genes produce proteins considered “defective” as they become inactive. That is, they are hidden (recessive) with the presence of a dominant gene manifesting its characteristics in the absence of its dominant allele.
They are represented by lowercase letters, aa, bb and vv and unlike the dominants, they express their character only in double dose, that is, homozygous recessive (pure).
Learn more about the topic by reading the texts:
- Phenotype and Genotype
- Homozygous and Heterozygous
Recessive Features
Some features expressed in the recessive allele genes:
- straight nose
- glued ear lobe
- Dimpled chin and straight
- Thin lips
- blond and red hair
- Blue eyes
- Does not have the ability to roll the tongue
- straight little finger
- straight thumb
- Left-handed
- Negative Blood Type
Recessive Gene-Related Diseases
Some diseases related to recessive allele genes:
- color blindness
- albinism
Continue your research by reading the articles:
- Introduction to Genetics
- chromosomes
- homologous chromosomes
- Inheritance
