Living Environment Translated English 2014 | Page 24

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o The phenotype is the way the organisms looks as a result of
the genotype.
 GG- looks dominant ( green)
 gg- looks recessive (yellow)
 Gg- looks dominant( green)
Principles of Heredity:
o Traits are controlled by alleles on chromosomes.
o An allele’s effect is dominant or recessive.
o When a pair of chromosomes separate during meiosis, the
different alleles for a trait move into separate sex cells.
Incomplete dominance is when both alleles for a trait are equal.
o There are no dominant or recessive alleles.
o Two different uppercase letters represent each allele.
( Ex: R= red W= white)
o The genotypes follow the same pattern as regular dominant/
recessive crosses:
 RR
 WW
 RW
o The phenotypes DO NOT follow the same patterns as regular
dominant/ recessive crosses.
 RR= looks red
 WW= looks white
 RW= looks pink ( it is a blend of the two allele colors)
Many traits are controlled by two or more alleles.
Polygenic inheritance is the name given to traits that are controlled
by more than two alleles. ( Ex: eye color, hair color, blood type)
Autosome- chromosomes that contain genes for characteristics not
directly related to the sex of the organism. Humans have 22
autosomes.
Sex chromosome- directly controls the development of the sex of
the offspring.