Download I. Heredity Vocabulary - Parkway C-2

Test #5- Mendelian Genetics and Human Heredity (Chapters 11 & 14)
I. Heredity Vocabulary
 Heredity –________________________________________________________________________

Parental Generation (P1 ) – ________________________________

Filial Generation (F1 ) – ___________________________________

Pure – _________________________________________________
_________________________________________________

Hybrid - offspring of crosses between pure parents with different traits
II. Mendel’s Experiments and Results

Mendel crossed two pure traits and saw that only one of the traits appeared in the F 1 generation, only to
reappear in the F2.

Mendel concluded that something inside the plant controlled which of the two traits appeared, he called it a
factor. What Mendel called a factor, we call a _____________________.

Mendel concluded that since there were two forms of every trait/characteristic he studied (height, color,
seed texture, etc.) that there were two factors/genes controlling each trait.

Gene – _________________________________________________________________________

Allele – Alternate forms of a trait (tall vs. short, round pea vs. wrinkled pea, etc.)
Mendel’s Principles (based on observational evidence without the help of microscopes, chemical evidence, etc...)
 Why is Gregor Mendel called the “Father of Genetics” – ___________________________________
_____________________________________________________________________________
1.
Principle of Dominance & Recessiveness – When 2 different factors for the same trait appear in a organism,
1 factor (or “gene”) will dominate or be expressed, while the other
factor/ gene will not appear or be expressed.
*Ex. tall pea plant X short pea plant = tall pea plant
2. Principle of Segregation – Since all organisms have 2 factors/genes for each trait, then
during the making of sex cells (meiosis) there must be a
separation of factors, one to each new sex cell (during
anaphase).
3. Principle of Independent Assortment – Factors for different traits are not connected,
they are sent to sex cells independent of each
other (just because the plant was tall it need not have round seeds).
 What could cause the Principle of Independent Assortment to be incorrect? -
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* How far apart different genes are on a
chromosome is indicated by how often
the genes are found together. Linked
genes do not assort independently, they
tend to get sent to sex cells together
because they are so close to each other
on the chromosome. This information
has helped scientists build chromosome
maps.
Many organisms are used today to study heredity. Zebrafish and Fruit Flies are just a couple of examples.
 Why are these good organisms to study –
*
*
*
*
*
*
IV. Genetic Crosses
Dominant alleles will be symbolized with a capital letter (T), Recessive alleles with a lower case letter of the
dominant allele (t).
Genotype – The actual genes an organism possesses (TT, Tt, tt) - one from each parent
Phenotype – The outward appearance of the organism, which is determined by its genotype
(TT = Tall, Tt = Tall, tt= short)
Homozygous – ______________________________________________________________________
Heterozygous – _____________________________________________________________________
Probability – The likelihood that a specific event will occur. It can be expressed as a decimal, percentage,
fraction, or a ratio.
Ex. Flipping a coin. What is the chance of getting 1 heads?
What is the chance of getting 3 heads in a row?
Punnett Square – A tool used to predict the genotypes and phenotypes of genetic crosses.
How to set up a punnett square:
T
t
1) Identify and abbreviate all known alleles (T = tall, t = short)
t
Tt
tt
2) Write the genotype of the parents to be crossed (Tt x tt)
t
Tt
tt
3) Draw a punnett square and put one parent across the top and the other down the side.
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4) Complete the punnett square. Place the parental alleles in the empty boxes of their corresponding
row/column.
5) List all genotypes and phenotypes in probability form.
Offspring Genotypes: Tt = 50%
tt = 50%
Offspring Phenotypes: Tall = 50%
Short = 50%
A. Simple Dominance and Recessiveness
Tall is dominant to short. Cross two parents who are both heterozygous for height.
Alleles =
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
B. Codominance – When both forms of a trait are dominant. The resulting phenotype for a heterozygous
offspring is a combination of the two traits. Ex: White x Red = red + white speckles (Roan)
Both Red ( R ) and White ( W ) are dominant. RW would be both red and white and look roan. Cross a red horse
with a white horse.
Alleles =
Parental Genotype =
Offspring Genotype =
Offspring Phenotype =
C. Incomplete Dominance – When neither form of a trait is dominant. The resulting phenotype for a
heterozygous offspring is usually a mix. Ex: White x Red = Pink
Neither red nor white is dominant. In incomplete dominance, heterozygotes would look pink. Cross two pink
flowers.
Alleles =
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
D. Multiple Alleles- When more than two alleles (forms of a trait) determine the phenotype
Alleles = A, B, O (A and B are both dominant, while O is recessive)
Blood Types:
AA (homo) or AO (hetero) = Type A
AB = Type AB
BB (homo) or BO (hetero) = Type B
OO = Type O
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 Heterozygous Type A x Homozygous Type B
Alleles:
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
E. Genetic Problems involving Two Traits:
Alleles: T = Tall, t = short, R = Round, r = wrinkled
Homozygous dominant for Height & Homozygous recessive for Seed Texture x Heterozygous for both traits
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
F. Sex-linked Traits
Sperm (male)
1. Sex Determination
X
X
Eggs (female)
X
Y
a) Sex Chromosomes – Chromosomes that determine the gender of an organism (XX = female, XY = male).
b) Autosomes – ____________________________________________________________________
(22 pair in human body cells).
Human cells - 2 sex chromosomes
Males - __________
Females- _________
+ 44 autosomes = _____ chromosomes per cell
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2. Sex linked punnett squares
Sex-linked traits are those carried on the X chromosome, such as colorblindness or male pattern baldness:
N = Normal Vision n = colorblind
Possible female genotypes: XN XN = _____________
X N Xn = ______________
Possible male genotypes:
Xn Y = Colorblind male
XN Y = Normal
X n Xn = ____________
What does “carrier” mean? Why can’t males be carriers for sex-linked traits?
__________________________________________________________________________________
__________________________________________________________________________________
Cross a normal visioned male with a carrier female
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
V. Genetic Disorders: Some diseases can be inherited from our parents through alleles that they pass down.
A. Chromosomal abnormalities
1. Down Syndrome: Caused by a trisomy (3) of chromosome 21; produces mild
to severe mental retardation. Most common cause is
non-disjunction- _____________________________
__________________________________________
2. Turner’s Syndrome: Caused by a missing X chromosome (genotype XO). Most women with Turner’s
syndrome are sterile because their sex organs do not develop during puberty.
3. Klinefelter’s Syndrome: Caused by an extra sex chromosome (genotype XXY). Men with this disorder
have underdeveloped sex organs, abnormally long legs and arms, and large hands.
B. Dominant Allele
1. Achondroplasia: The most common form of dwarfism.
2. Huntington's disease: Symptoms develop in the 30's when the nervous system begins breaking down.
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C. Codominant Allele
1. Sickle cell disease: Sickle-shaped blood cells develop that can cause blockage in blood vessels.
D. Recessive Allele
1. Tay-Sachs disease: Results in nervous system breakdown and death in the early years.
2. Cystic Fibrosis: Excess mucus is present in the lungs, the digestive tract, and the liver. People with CF
are more susceptible to infections, respiratory and digestive problems
E. Sex-linked Recessive Disorders
1. Hemophilia: Missing a protein necessary for blood clotting. People with this disease can die from a minor
cut.
2. Color blindness: Symptoms can vary from difficulty distinguishing similar colors to complete absence of
color vision.
VI. Human Heredity
Pedigree – A family record that shows how a trait is inherited over several generations. It is useful in helping
determine the risk of having a child with a family disease
Pedigree Key:
1
1
2
Male (no disease)
Male (diseased)
Male (carrier)
1
1
2
3
5
4
Female (no disease)
Female (carrier)
1
2
Female (disease)
Mates
2
Offspring
Death
Siblings
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In humans, Albinism is a recessive trait. The disorder causes a lack of pigment in the skin and hair making an albino
appear very pale with white hair. Fill in the genotypes of all individuals.
What phenotypes would these genotypes have: AA= normal
Aa = _____________
aa = ______________
How many generations are depicted in this pedigree?
How many children does the initial couple have?
What are the sexes of those children?
How many great grandchildren does the initial couple have?
How many individuals in this pedigree are carriers of albinism?
Test #5 Format: Genetics
Test Date: _________________
Multiple Choice from the notes:
 Gene: _______________________________________________________________________________________
 Allele: ______________________________________________________________________________________
 Principle of Dominance and Recessiveness: ____________________________________________________________
 Principle of Segregation: _________________________________________________________________________
 Principle of Independent Assortment: _______________________________________________________________
 Phenotype: ___________________________________________________________________________________
 Genotype: ____________________________________________________________________________________
 Homozygous: _________________________________________________________________________________
 Heterozygous: ________________________________________________________________________________
 Probability: ___________________________________________________________________________________
 Multiple alleles: _______________________________________________________________________________
 Codominance: _________________________________________________________________________________
 Incomplete Dominance: __________________________________________________________________________
 Down Syndrome: _______________________________________________________________________________
 Turner’s Syndrome: ____________________________________________________________________________
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 Klienfelter’s Syndrome: __________________________________________________________________________
 Achondroplasia: _______________________________________________________________________________
 Huntington’s Disease: ___________________________________________________________________________
 Sickle Cell: ___________________________________________________________________________________
 Tay Sach’s: ___________________________________________________________________________________
 Cystic Fibrosis: ________________________________________________________________________________
 Hemophilia: __________________________________________________________________________________
Written Questions –

Be able to work through a pedigree problem (determine which individuals would be heterozygous, identify what the
symbols on the pedigree mean, be able to write out the genotypes of individuals on the pedigree)

Be able to work through four (4) punnett squares (could include dominant/recessive, blood typing, sex-linked,
codominance, and incomplete dominance).
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