Human genetics
genes exist in varieties called alleles that can be dominant or recessive.
describe the inheritance of selected traits in humans.
Most human traits depend on genetic assemblies (multigenetic inheritance). These include eye colour, hair colour and structure, shape of the ears, right and left‑handedness, height, body weight, intelligence, cholesterol concentration in the blood. Some genetic diseases are inherited from only one gene.
Table. Selected dominant and recessive human traits dependent on gene assemblies
Dominant feature | Recessive feature |
hair is not red | hair is red |
dark hair | light hair |
protruding ears | ears not protruding |
the ability to roll tongue | lack of ability to roll tongue |
right handed | left handed |
presence of dimples in the cheeks | no dimples in the cheeks |
presence of freckles | no freckles |
long eyelashes | short eyelashes |
free earlobes | attached earlobes |
simple thumb | hitchhikers thumb |
oval shape eyed | round eye shape |
oval shaped face | square shaped face |
putting the left thumb on the right when folding hands | putting the right thumb on the left when folding hands |
Use the table to determine what you have, and what .
Use the table to determine what dominant traitsdominant traits you have, and what recessive traitsrecessive traits.
Krzysio grew up in good conditions and has always been a healthy child. Today he is a teenage athletic and full of life blond boy. Krzysia's parents are surprised by the colour of their son's hair because they both have dark hair. Indicate all the arguments that should be used to explain to the boy's parents where the colour of his hair came from.
- Both Krzysia's parents have genes that condition a light hair colour.
- Krzysio did not inherit from his parents the genes conditioning the dark hair colour.
- Alleles conditioning the dark hair colour are predominant with alleles conditioning a light hair color.
- Krzysia's light hair is the result of the impact of adverse environmental conditions.
Summary
Most human traits are conditioned by a set of many genes that occur in the form of two or more alleles.
Keywords
dominant trait, recessive trait, allele
Glossary
cecha dominująca – cecha determinowana przez allel dominujący danego genu. Ujawnia się w fenotypie zarówno w układzie homozygotycznym jak i heterozygotycznym.
cecha recesywna – cecha determinowana przez allel recesywny danego genu. Ujawnia się w fenotypie jedynie w układzie homozygotycznym.