STRATEGIC

INTERVENTION MATERIAL

(S.I.M.) IN SCIENCE 9

Non-Mendelian

Patterns of Inheritance:

Codominance and

Incomplete dominance

Prepared by: ROMNICK O. SEGUIBAN

GUIDE CARD

TASK:

Explain and describe the characteristics of

codominance and incomplete dominance;

Find out the ratios or percentages of

identified genotype and phenotype

Use punnet square to show how an allele of

the parent affects their offspring

LEAST MASTERED SKILL:

Identifying the patterns of inheritance

Computing phenotypic and genotypic ratio of

non-mendelian genetics

OVERVIEW

In Grade 8, you learned that cells

divide to produce new cells and meiosis is one of

theprocesses producing genetic variations in

Mendelian patterns of inheritance. You will focus

on describing the location of genes in

chromosomes, explain the different patterns of

non- Mendelian inheritance and describe the

molecular structure of the DNA.

Gregor Mendel’s principles form the

base for the understanding of heredity and

variation. Although Mendel’s work failed to

discuss thoroughly the ‘factors’ or genes he

mentioned in his laws of inheritance, his findings

prompted other scientists to probe further into the

mystery of heredity. Several researches were

conducted after the rediscovery of Mendel’s work.

Mendelian laws of inheritance have

important exceptions to them. For example, not all

genes show simple patterns of dominant and

recessive alleles.

In incomplete dominance, a

heterozygote shows a phenotype that is

intermediate between the two homozygous

phenotypes. Neither allele is dominant over the

other.

Another pattern of inheritance is

codominance. This results when one allele is not

dominant over the other. The resulting

heterozygotes exhibit the traits of both parents.

ACTIVITY 1: “What pattern am I?

Identify if the following pictures exhibits CODOMINANCE

or INCOMPLETE DOMINANCE.

1.)

2.)

3.)

4.)

ACTIVITY 2: “FAIR & SQUARE”Use punnet square to predict their offspring based on

the type of inheritance.

1. Leaf color is controlled by

incomplete dominance. The allele

green leaf is “G” and “Y” for

yellow leaf. Both parents are

heterozygous.

2. Hair color is

controlled by

codominance. The

allele for blonde hair is

“B” and “G” for

grayish hair. The father

is a homozygous

blonde while the

mother is a

homozygous black hair.

ACTIVITY 3: “RA-TIO ME”Compute for the phenotypic ratio and

genotypic ratio of the following statements:

1. 2 pit bull dogs are homozygous and their skin color

is controlled by CODOMINANCE. The father has

dark skin while the mother has white skin.

2. A roan cow is a product of

codominance. What will be

the phenotypic ratio and

genotypic ratio if both parents

are roan cows?

3.The pattern of inheritance of black and white fur

of mice is controlled by incomplete dominance.

The father is a heterozygous and the mother is a

pure white.

ASSESSMENT CARD

Answer the following questions:

1.Explain the difference between incomplete dominance and

codominance:

2.In some chickens, the gene for feather color is controlled by

codominance. The allele for black is B and the allele for white is W. The

heterozygous phenotype is known as erminette.

a.What is the genotype for black chickens? ____

b.What is the genotype for white chickens? ____

c.What is the genotype for erminette chickens? ____

3.If two erminette chickens were crossed, what is the probability that:

a.They would have a black chick? ____%

b.They would have a white chick? ____%

4.In snapdragons, flower color is controlled by incomplete dominance. The

two alleles are red (R) and white (W). The heterozygous genotype is

expressed as pink.

a.What is the phenotype of a plant with the genotype RR? ___________

b.What is the phenotype of a plant with the genotype WW? ___________

c.What is the phenotype of a plant with the genotype RW? ___________

5.A pink-flowered plant is crossed with a white-flowered plant. What is the

probability of producing a pink-flowered plant? ____

ENRICHMENT CARD

REMEMBER THIS: If it is codominance BOTH alleles are expressed. If it

is incomplete dominance, alleles are MIXED or they BLEND when

expressed.

Go to youtube.com to

check out tons of related

videos about

codominance and

incomplete dominance. I

recommend this one for

you:

https://www.youtube.com/w

atch?v=YJHGfbW55l0

CHALLENGE:

a. If Gregor Mendel worked on

simple dominance, who discoved

incomplete dominance using four

o’ clocks?

b. What blood type exhibits

codominance?

ANSWER

CARD

ACTIVITY 1:

1. CODOMINANCE

2. INCOMPLETE DOMINANCE

3. CODOMINANCE

4. INCOMPLETE DOMINANCE

ACITIVITY 2:

1)

homozygous yellow leaf

homozygous green leaf

yellow green leaf

2.)

Blonde & grayish hair

Y G

Y YY YG

G YG GG

B B

G BG BG

G BG BG

ACTIVITY 3:

1) All or 100 % will have both skin color be expressed

1) 1 BB: 2BW: 1 WW

1 White cow: 2 Roan cows: 1 Brown

3) 1 BW: 1 WW

1 Gray fur: 1 pure white fur

ASSESSMENT:

1)INCOMPLETE DOMINANCE = ALLELES ARE MIXED/

BLEND; CODOMINANCE = BOTH ALLELES ARE

EXPRESSED

2)a. BB

b. WW

c. BW

3) a.25 %

b. 25%

4) a. RED FLOWER COLOR

b. WHITE FLOWER COLOR

c. PINK FLOWER COLOR

5) 50%

REFERENCE CARD

DEPED Learners’ Material Science9 Module 2 pp. 1-7

Modern Biology (Philippine Edition) pp.115 -127 by Velasquez,

C. & Asis, C.;

Concepts of Genetics pp 94 – 100 by Brooker, R.;

http://www.ck12.org/biology/Non-Mendelian-

Inheritance/lesson;

http://www.vcstulsa.org/faculty/Schenfield160/editoruploads/

files/genetics%20worksheet