Human Trait Inheritance Note

KARNIVAL AKADEMIK KMPh 2019

Group Heredity
(1M1D14)

At the end of activity, students should be
able to:
1. Determine the inheritance of genetic

trait controlled by single gene in
human.
2. Identify dominant and recessive
phenotype in human
3. Realize the uniqueness each individual
inherit from their parent





Genes come in different varieties, called alleles. Somatic
cells contain two alleles for every gene.

Each allele provided by parent of an organism (father
and mother). Combination of alleles can be homozygous
dominant, heterozygous or homozygous recessive (genotype).

Often, it is impossible to determine which two alleles of
a gene are present within an organism's chromosomes. It is
much easier to observed physical character/appearance of that
organism (phenotype).

However, an allele that is hidden, or not expressed by an
organism, can still be passed on to that organism's offspring
and expressed in a later generation.

Shape of nose
Attached or detach earlobe

Ability to roll tongue
Present or absent of dimple

Right or left handed
Ability to bend thumb
Hair line style and hair type

Cleft clin

CHARACTERISTIC 1: SHAPE OF NOSE
Straight nose (E_) is dominant to

curved nose (ee).

CHARACTERISTIC 2: EARLOBE
Free earlobe (P_) is dominant to

attached earlobe (pp).

CHARACTERISTIC 3: TONGUE ROLLING
Ability of tongue rolling into “U” shape (C_) is dominant

to inability of tongue rolling into “U” shape (cc).

CHARACTERISTIC 4: DIMPLE
Individual with are genotypically (D_) dominant compared

to those without dimple (dd).

CHARACTERISTIC 5: LEFT-HANDED
The right-handed characteristic (H_) is dominant to

left-handed (hh).

CHARACTERISTIC 6: HITCH HIKER THUMB
The ability to bend thumb at 60 angle or more are
genotypically (tt) recessive compared to normal thumb –

bending (T_)

Straight nose (E_) Curved nose(ee)

Free earlobe (P_) Attached earlobe (pp)

Can roll tongue (C_) Can’t roll tongue (cc)

Have dimple(D_) Doesn’t have dimple (dd)

Left – handed (hh) Right – handed (H_)

Normal thumb bending (T_) Ability to bend thumb 60˚(tt)

Widow’s peak(W_) Straight hairline(ww)

Cleft chin (K_) No cleft chin (kk)

Curly hair(RR) Wavy hair(Rr) Straight hair(rr)