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DAY 1: Mendelian Genetics Vocabulary
A. Genetics- Study of
B. Heredity- The passing on of characteristics (traits) from _______________ to
____________________
C. Trait – A particular
that can vary from one individual to
another. Ex:
________
D. Fertilization- Joining of male and female
(reproductive cells)
during
___________reproduction
E. Genes- Section of a chromosome that determine the trait we will inherit Ex: Sally
has the gene for brown hair
F. Allelesof one gene
Ex: Brown, red, or blond hair are all different forms the hair color
gene
G. Dominant Geneexpressed if present
for a trait
 Dominant allele = capital letter (B)
H. Recessive Gene- Only expressed if
__________ are
present for that trait
 Recessive allele = lowercase letter (b)
PRACTICE! Use the term Dominant or Recessive to identify the type of trait
shown.
1. TT
4. SS
2. tt
5. ss
3. Tt
6. Ss
I. Homozygous- Organisms have
alleles for a trait
 Ex: RR (BIG/BIG) or rr (small/small)
J. Heterozygous- Organisms have
alleles for a trait
 EX: Rr (BIG/small)
PRACTICE! Use the term Homozygous or Heterozygous to identify each of the
following:
1. AA
4. gg
2. Aa
5. GG
3. Mm
6. Gg
K. Genotype- the genetic makeup (________) or combination of _______
___________________ (one from mom and one from dad)
 Ex: QQ, Qq, qq
L. Phenotypecharacteristics of the trait
 Ex: Brown Hair (what you see)
EGG
SPERM
Gregor Mendel (1822-1884)
A. Austrian Monk
B.
The “
________________”
C.
Cross Bread common
_______
to study the inheritance of traits through each
generation.
Mendel’s Pea Plant Experiment
A. P1 –
B. F1C. F2Mendel’s Conclusions:
A. Biological Inheritance is ________________ from one
________________________ to the next.
 Ex: your traits were determined by your
parents’ genes that were passed onto you.
PAP
B. Law of
 During _____________, the pairs of _________
__________________ so that each gamete receives
only one gene for each trait
C. Law or Principal of
 Some alleles are _________________ and some are
______________________.
 Recessive traits will only show up if dominant is
___________ present
Punnett Squares following Mendelian Rules of Genetics
A. A Punnett Square is a __________________ used to _________________ the outcome of a
particular cross or breeding experiment
B. Used to determine the __________________________of _____________offspring’s
genotypes and phenotypes
C. This does ___________determine how many offspring will be produced or exactly what the
offspring’s genotype and phenotype will be…just the chances!
D. There are five steps (you must always show your work)
1. Key- List the trait, Both alleles, and which phenotype corresponds with each
allele
2. Parents- List the genotypes of each parent
3. Draw the Punnett square
4. Determine the genotype ratio
5. Determine the phenotype ratio
Complete the following Punnett squares using all 5 steps
SAMPLE PROBLEM: Wavy hair is dominant to straight hair. Cross two heterozygous parents.
1. Key:
3.
Punnett Square
2. Parents: ____X_____
4. Genotype:
5. Phenotype:
Worksheet Problems: YES, THIS IS FOR A GRADE. YOU need to complete it!
For each phenotype below, list the POSSIBLE genotypes (remember to use the letter of the dominant trait)
Brown eyes are dominant to blue eyes
Widow’s peak is dominant to straight hair line
________Homozygous Brown
________Widow’s peak
________Heterozygous Brown
________Widow’s peak
________blue
________straight hair line
PAP
1. In rabbits, black hair color is dominant to white. Cross homozygous black rabbit with a white rabbit.
1. Key:
2. Parents: _______X_______
4. Genotype:
5. Phenotype:
2. In roses, red is dominant to yellow. Cross a homozygous red rose with a heterozygous red rose
1. Key:
2. Parents: ________X_______
4. Genotype:
5. Phenotype:
3. In cats, long tails are dominant to short tails. Cross two heterozygous long tail cats.
1. Key:
2. Parents: ________X_______
4. Genotype:
5: Phenotype:
4. In lizards, green skin color is dominant to purple. Cross a heterozygous green lizard with a purple lizard.
1. Key
2. Parents:
4: Genotype Ratio
5: Phenotype Ratio
Match the terms with the definitions.
1. _____ Genetics
2. _____ Dominant
3. _____ Genes
4. _____ Homozygous
5. _____ Gamete
6. _____ Recessive
7. _____ Heterozygous
8. _____ Heredity
9. _____ Phenotype
10. _____ Genotype
A. the weaker of a pair of genes
B. When the pair of genes are identical
C. the study of heredity
D. The passing of traits from parents to their young
E. the stronger of a pair of genes
F. sex cells, wither male or female
G. segment of DNA that codes for a particular protein
H. the physical appearance of an organism
I. the actual genetic make-up of an organism
J. when the pair of genes are different
DAY 1
1. In humans, a widow’s peak is dominant to a straight hair line. Cross homozygous widow’s peak with a
straight hair line.
1. Key:
2. Parents: _______X_______
4. Genotype:
5. Phenotype:
2. In humans, a widow’s peak is dominant to a straight hair line. Cross a straight hair line with a straight hair
line.
1. Key:
2. Parents: _______X_______
4. Genotype:
5. Phenotype:
3. Mendel discovered that yellow pea color is dominant to green pea color. Cross a green pea plant with a
heterozygous yellow pea plant.
1. Key:
2. Parents: _______X_______
4. Genotype:
5. Phenotype:
4. Using Mendel’s information about pea plants, (yellow is dominant to green) cross a homozygous yellow
pea plant with a heterozygous yellow pea plant.
1. Key:
2. Parents: _______X_______
4. Genotype:
5. Phenotype:
Mendelian Genetics- Dihybrid Crosses (Crossing 2 Traits/Factors)
Review of Monohybrid Crosses

Remember, monohybrid crosses involve only ____________ trait
Example: In fruit flies, red eyes are dominant over white eyes. RR x rr
In this example you are only examining the ______ ______________ trait.
Dihybrid Cross: the study of ________ pairs of contrasting traits at the same time
Example: Fur color WITH Coat Texture
Fur Color:
B: Black
b: White
Coat Texture:
R: Rough
r: Smooth
Mother is black fur AND rough coat
BbRr
Father is black fur AND rough coat
BbRr
Notice that each parent has _____ ________so that results in _____ ________ (1 trait= 2 alleles)
The Law of Independent Assortment

During ____________formation, segregating pairs of unit ____________ (alleles) assort
__________________ of each other when on different chromosomes.

The two traits are inherited totally independently of each other.

Example: Fur color is inherited independently of coat texture.
Sample problem 1: We will cross a heterozygous individual with another heterozygous individual. Their
genotypes will be BbRr x BbRr
Step 1: Find ALL possible gametes that can be made from each parent.
Remember, each gamete must have one B and one R. USE THE FOIL METHOD
BbRr
x BbRr
Step 2: Arrange all possible gametes for one parent on the top of your Punnett Square and the other
parent on the side
Fur Color:
B: Black
b: White
Coat Texture:
R: Rough
r: Smooth
Step 3: Fill in the Punnett Square
(find the possible genotypes of the
offspring)
Step 4: Figure out the genotypic and phenotypic ratios:
How many of the offspring would have a black, rough coat?
How many of the offspring would have a black, smooth coat?
How many of the offspring would have a white, rough coat?
How many of the offspring would have a white, smooth coat?
_____
_____
_____
_____
Phenotypic ratio _____:_____:_____:_____
Sample Problem 2:
What are the genotypic and phenotypic ratios in the offspring resulting from a cross between two people
heterozygous for eye color and eyelash length? What is the phenotype of the parents in this cross?
B – Brown
b – Blue
L - Long
l – short
Parents are heterozygous for both traits.
The cross is B b L l
x
B b L l.
STEP 1: Determine the possible gametes that the parents can produce. USE FOIL for independent
assortment
STEP 2: Enter the possible gametes at the top and side of the Punnett square.
Always keep the same letter first and capitals of each first.
STEP 3: Complete the Punnett square by writing the alleles from the gametes in the appropriate boxes.
The alleles from the gamete above the box and the alleles from the gamete to the side of the box are combined
inside each of the boxes. The letters inside each box represent the probably genotypes of the offspring resulting
from the cross.
STEP 4: Determine the genotypes of the offspring.
Count each row from left to right (as you read). Mark each one as it is used.
Determine the phenotypes of the offspring.
Count each row vertically (top to bottom).
Genotypes
Phenotypes
Practice Problems: In mice, the ability to run normally is a dominant trait. Mice with this trait are called running
mice (R). The recessive trait causes mice to run in circles only. Mice with the trait are called waltzing mice (r).
Hair color is also inherited in mice. Black hair (B) is dominant over brown hair (b). For each of the following
problems, draw a Punnett Square in the space provided and fill in the information on the indicated lines.
CREATE THE KEY:
1. Cross a heterozygous running, heterozygous black mouse with a homozygous running, homozygous black
mouse.
Parents: _________X__________
2. Cross a homozygous running, homozygous black mouse with a heterozygous running, brown mouse.
Parents: _________X__________
3. Cross a waltzing, brown mouse with a waltzing, brown mouse.
Parents: _________X__________
4. Cross a homozygous running, heterozygous black mouse with a waltzing brown mouse.
Parents: _________X__________
5. Cross a heterozygous running, brown mouse with a heterozygous running, homozygous black mouse.
Parents: _________X__________
6. Cross a hemophilic man with blood type AB with a hemophilic-carrier woman with
blood type A (homozygous).
Parents: _________X__________
7. A colorblind man with type B blood, whose dad was type O marries a normal woman with
no colorblindness in her family and has type AB blood. What are the possible ratios for future children?
Parents: _________X__________
8. A woman whose dad has Duchenne’s muscular dystrophy and type AB blood marries a man
that is normal with type AB. What are the possible outcomes for their future family?
Parents: _________X__________
Non-Mendelian Incomplete Dominance
*Exceptions to the Mendel Rule*
Notes:
Incomplete Dominance
A. A cross between organisms with
phenotypes
Ex: Red x White
B. Produce offspring with a
phenotype that is a
____________________ of the parental traits
C. EXAMPLE: If a homozygous
Ex: Pink is a blend of red & white
flowered snap dragon plant (RR) is
crossed with a homozygous
flowered snap dragon plant (WW), all of
the F1 offspring will have
flowers.
1. RED flower x WHITE flower  PINK flower
*be careful- notice that the alleles are ALL capitalized
D. The
of
individuals is
(in the middle) between those of two homozygotes
Sample Problem:
In another flower, if red (RR) and blue (BB) flowers are crossed, they produce a 3rd purple (RB) flower
What would be the genotype ratio and phenotype ratio if you crossed two purple flowers?
Cross of two purple flowers (parents)
_______ X _______
What are gamete possibilities?
genotype ratio ________________________
phenotype ratio _______________________
Can you have a heterozygous red or hybrid blue flower? _______
Section 1: Incomplete dominance in four-o’clocks - When a four-o’clock plant homozygous for red flowers is
crossed with one homozygous for white flowers, all of the offspring bear pink flowers. Cross a homozygous red
flowered plant with a homozygous white flower plant.
1. Key:
2. Parents:
4. Genotype:
5. Phenotype:
What is the genotype of the F2 generation from the problem above?
1. Key:
2. Parents:
4. Genotype:
5. Phenotype:
Explain how the red or white variety of four-o’clocks is maintained:
___
Section 2: Inheritance of color in MInk – The same principle of inheritance of coat color in Shorthorns also
applies to mink. When a mink homozygous for white fur is crossed with one homozygous for black fur, the
offspring are all Koh-i-nur or shiny black cross. Show the result in crossing two Koh-i-nur minks. Show your work.
1. Key:
2. Parents:
4. Genotype:
5. Phenotype:
Explain how people who raise mink could maintain only minks with white fur:
Section 3: Practice Incomplete Dominance – show all work.
1. In noses, dry nostrils are incompletely dominant to runny nostrils. A cross will result in a slimy nostril.
a. Cross a slimy nostril with a dry nostril.
Key:
Parents:
Genotype:
Phenotype:
b. Cross a dry nostril with a runny nostril.
Key:
Parents:
Genotype:
Phenotype:
c. Cross two slimy nostrils.
Key:
Parents:
Genotype:
Phenotype:
2. In people, happy people are incompletely dominant to sad people. A cross between the happy and sad people
results in a grumpy person. Cross two grumpy people.
Key:
Parents:
Genotype:
Phenotype:
Non-Mendelian Genetics: Codominant Traits with Blood Typing
Codominance
A. A cross between organisms with
_
phenotypes
1. Ex: Red x White
B. Produce offspring with a
phenotype that
displays
traits at the same time
1. Ex: Red and White striped
C. EXAMPLE: If a homozygous
homozygous
flowered snap dragon plant (RR) is crossed with a
flowered snap dragon plant (WW), all of the F1 offspring will have
flowers.
1. RED flower x WHITE flower  RED AND WHITE flower
Human Codominance
A. Sickle-Cell Anemia
1. An individual who is heterozygous for sickle-cell alleles will express BOTH _________
and
blood cells.
 The oxygen carrying protein hemoglobin differs by one amino acid than the regular cause
the shape to change: Normal RBC are
are
and abnormal
or sickle shaped.
2. Abnormally shaped blood cells
,
______________, and result in tissue damage and
.
3. Heterozygous individuals are said to have the sickle-cell trait because they show signs of sickle-cell
related disorders if the availability of oxygen is reduced.
B. Blood types
1. Blood type is determined by
alleles. This
means there are more than two types of alleles possible that can make up a paring.
_______
: red blood cells produce A antigens (protein)
on the outside of the cell
A. Allele is expressed IA because it is
_______
_______
: red blood cells produce B antigens (protein)
on the outside of the cell
B. Allele is expressed IB because it is _________
_______
: red blood cells will
produce an antigen (protein)
C. Allele is expressed i because it is
2. Determining Blood types is necessary before you receive a blood transfusion because incompatible
red blood cells
together or clot causing death.
3. Your immune system or antibodies recognizes the red blood cells belonging to you. If cells with a
_____ ____________ of antigen enter your body your immune system will attack them.
Complete the following chart:
Phenotype or blood type
Type A
All genotypes possible
Type B
Type AB (Codominant)
Type O (recessive)
***The true universal blood donor are O-
***The true universal recipient is AB+
SAMPLE PROBLEMS:
Cross a parent with Type AB blood with a parent that has heterozygous type A blood.
Parents: ___________X_____________
Genotype:
Phenotype:
Cross a heterozygous type A blood father with a heterozygous type B blood mother.
Parents: ___________X_____________
Genotype:
Phenotype:
Practice Problems: Include all steps.
1. Is it possible for parents with type A blood to have a child with type O blood? __________
Show your work and PROVE your answer.
A. If it is possible, list the necessary genotypes of the parents and explain why their child could have a
different blood type.
B. What is the genotype of a child with type O blood? ___________
C. Work the following cross: Heterozygous type A x heterozygous type B
Parents: ___________X_____________
Genotype:
Phenotype:
PAP
2. A man with homozygous A blood has children with a woman with heterozygous B blood. What are the
possible blood types for their children?
Parents: ___________X_____________
Genotype:
Phenotype:
3. Pick one child from problem #2 and cross that person with a person with heterozygous A blood.
Parents: ___________X_____________
Genotype:
Phenotype:
4. Suppose that a man with type A blood marries a young woman who has type AB blood. What blood types
would you expect to find among their children. Remember to take all possibilities into account.
5. Mr. Jones was taken to court and charged with being the father of a woman’s child. He is homozygous
type A blood. She is heterozygous type B blood. The child is type O blood. Is Mr. Jones the father? Show
all your work.
6. Two newborn babies were accidentally switched in a hospital. In an effort to correct the mistake blood
types of the babies and parents were determined. Here are the results of the blood types. Which baby
belongs to which parent?
Baby 1 – type O
Mrs. Brown – type B
Mrs. Smith – type B
Baby 2 – type B
Mr. Brown – type AB
Mr. Smith – type B
A. Baby 1 belongs to the parents ________________________. Prove your answer with 4 steps.
B. Baby 2 belongs to the parents ________________________. Prove your answer with 4 steps.
Non- Mendelian Genetics: SEX- LINKED TRAITS
A. Determining Sex
1. Humans have a
number of
chromosomes or
2. 22 of the pairs are autosomes, they are the
for
males and females
3. The 23rd pair of chromosomes
in males
and females
 These are the sex chromosomes and are
indicated by

___ and
determine the baby’s sex.
B. Inheriting Sex linked traits
1. Genes located on the _________
___________________ are called sex- linked traits
2. Because the Y chromosome is small it carries
, including the male determinant sex gene.
3. Males who receive a
on the X
chromosomes will express the_______________
_________
because he cannot inherit on
the Y chromosome.

There is
4.
dominant allele to
the recessive gene
have a higher percent chance of expressing the recessive trait
C. Examples in Humans
1. Hemophilia

Causes a problem with

Caused by a ___________________ allele on the _______ chromosomes

Males: 1/10,000


Females: 1/10,000,000


Need __________ recessive allele from carrier mom
Need _________ recessive alleles; one from mom and one from dad
Sex- Linked Traits
2.
Color Blindness

People who have red-green color blindness cannot differentiate between the two colors.

Caused by a
___
allele on the X chromosomes
Sample problem 1:
A colorblind man marries a woman who is not colorblind. Assuming there is no colorblindness in the woman’s ancestr
what will most likely be the genotype and phenotypes of their sons and daughters? Show your work
a. Key:
e. Punnett Square
b. Parents:
c. Genotype Ratio:
d. Phenotype Ratio:
USE THIS CHART TO HELP YOU ANSWER THE PRACTICE PROBLEMS THAT FOLLOW!!
Colorblindness- C= normal
c’= colorblindness
Hemophilia- H=normal
h=hemophilia
PHENOTYPE
GENOTYPE
PHENOTYPE
GENOTYPE
Female normal
X
Female normal
X
X
X
Y
X
Female normal, Carrier
Female normal , Carrier
Female, color-blind
Female, hemophiliac
Male normal
Male, color-blind
X
Y
Male normal
Male hemophiliac
*Males either have colorblindness or they don’t. They only have one X chromosome that was received from the mothe
** More males have hemophilia and color blindness because males need one gene for hemophilia or
Color-blindness to occur.
PRACTICE PROBLEMS: SHOW ALL 5 STEPS!
A. A normal woman marries a normal man producing two colorblind sons, two normal sons
and three normal daughters. Show your work.
1. Key:
3. Punnett Square
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
B. A female carrier of hemophilia marries a normal male. What are the genotypes and phenotypes
of the possible offspring? Show your work.
1. Key:
3. Punnett Square
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
C. Normal man X Hemophiliac woman
1. Key:
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
3. Punnett Square
D. Hemophiliac man X Heterozygous normal woman
1. Key:
3. Punnett Square
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
E. Hemophiliac man X Homozygous normal woman
1. Key:
3. Punnett Square
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
F. If a normal woman marries a normal man and two of their three sons are hemophiliacs,
what is her genotype? Is this possible? Show this problem.
1. Key:
2. Parents:
3. Geno Ratio:
4. Pheno Ratio:
3. Punnett Square