Genetics Vocabulary
Group 1
Heredity
Trait
Allele
Locus
Characteristic
Dominant
Recessive
Word
heredity
he•red•i•ty
(noun)
Meaning
The passing of
genetic traits from
parent to offspring.
Latin:
hereditas = heirship
Examples
Her red hair is a
result of heredity
from her mother’s
side of the family.
Most cases of malepattern baldness is
heredity.
• In 1930s Heinrich Himmler of
Nazi party decided to enact
policy to increase numbers of
“racially pure” citizens
considered “Aryan”
– Blonde
– Blue eyes (green ok )
• Since he understood principles
of heredity, convinced blondehaired, blue-eyed soldiers and
women to breed more
children, married or not
• Entire organization called
Lebensborn which means
“fountain of life” in ancient
German
Lebensborn 1935 - 1945
Special attention was paid to
children born on Fuhrer’s
birthday, October 7
Writing Task:
Heinrich Himmler understood the
principles of heredity when he
instituted the “Lebensborn” project to
increase the number of blonde-haired,
blue-eyed “Aryans” in Germany.
Pair-Share
A
• I received my mother’s ___________
as a result of heredity.
B
• I received my father’s ____________
as a result of heredity.
Word
trait
trait
(noun)
Meaning
A genetically
determined
characteristic or
condition.
Latin:
tractus = tract
Examples
My dad’s Roman nose
is a trait that goes
back generations.
Monica’s weird feet
are a trait she
definitely did not
inherit from her mom.
• Royal intermarriage was a
common practice in Europe
through the ages to keep
pure royal bloodlines.
• The Hapsburg lip is a trait
that was found in the House
of Hapsburg royal line in
which the bottom lip
protrudes as a result of an
under bite.
• Many royal portraits of the
Hapsburgs shows this
common trait that was
passed down through the
generations.
Writing Task:
The Hapsburg lip is a trait found in one
royal family line as a result of years of
intermarriage in order to preserve the
royal bloodlines.
Pair-Share
A
• One trait I inherited is ___________
which is from my _______________.
B
• A second trait I inherited is _______
which is from my _______________.
Word
Meaning
Examples
If just one allele for
eye color is brown,
you will have brown
eyes.
allele
al•lele
(noun)
One of the
alternative forms
of a gene that
governs a
One allele for a gene
characteristic,
comes from your
such as hair color.
mother, the other
from your father.
German:
allelomorph =
changing gene
• Feather color in certain
chickens is a gene that is
determined by two alleles,
white and black.
• If a chicken has two white
alleles, it will be white. If a
chicken has two black
alleles, it will be black.
• If a chicken has one white
allele, one black allele, it will
not be gray, but actually
checkered with both black
and white feathers!
Writing Task:
A chicken having two black feather
alleles will result in it being black. If it
has one black allele and one white
allele, it will be checkered, both black
and white.
Pair-Share
A
• A gene that has two alleles is _____.
B
• Another gene that has two alleles is
_________.
Word
locus
lo•cus
(noun)
loci (plural)
lo•ci
Meaning
Examples
1. The place
where something
is situated or
occurs.
Geneticists are
working on finding the
locus for the skin
cancer gene.
2. The position in
a chromosome of
a particular gene
or allele.
The repeated DNA
sequence GCGCGCG is
found at many loci on
chromosome 12.
Latin: stlocus = a
place
Kidney gene
locus
Cancer gene
locus
Chromosome 9
• Certain cancer genes on
different chromosomes
cause cancer to different
organs depending on the
locus of the gene
• On chromosome 9, the
cancer gene’s locus is
near a locus for kidneys.
As a result, there is a
higher incidence of
kidney cancer when
those two loci are
physically close.
Writing Task:
Depending on the loci for certain
genes, cancer can affect organs if they
are located near the cancer locus on
the same chromosome.
Pair-Share
A
• The locus of my house is _________.
B
• The main loci for fights on campus is
___.
Word
Meaning
Examples
One of Mr. Jones’
unique characteristics
is his funny laugh.
A distinguishing
characteristic trait, quality, or Elizabeth Taylor’s violet
char•ac•ter•is•tic property.
eyes are a
(noun)
distinguishing
characteristic.
Greek:
charaktiras = a
mark
• Each President of the
United States seems to
have a physical quirk or
characteristic that
distinguishes him from
the others.
• Barack Obama’s quirky
characteristic seems to
be his big ears which
are excellent fodder for
comedians worldwide.
Writing Task:
Each individual has unique physical
characteristics that are inherited from
his or her parents. Everything from hair
color, to ear size, to eye color is handed
down through the generations.
Pair-Share
A
• One characteristic I inherited from
my _________ is ______________.
B
• One characteristic I inherited from
my _________ is ______________.
Word
dominant
dom•i•nant
noun,adjective)
Meaning
Commanding,
controlling, or
prevailing over
all others.
Latin: dominari
= strong
Examples
Brown eyes are
dominant over blue
eyes as a result of
evolution.
That student is a
dominant presence in
my 6th period class.
Artist’s interpretation of
an early ancestor.
• Current evolutionary
theory holds that human
beings evolved from
primates in central Africa.
• The first humans were
dark-haired, dark-skinned,
with dark-eyes.
• Current genetic models
show that all dark traits
are dominant over lighter
traits, since those lighter
traits are a result of
mutations.
Writing Task:
Why are blonde hair and blue eyes such
revered traits in Hollywood when brown
hair and brown eyes are dominant traits
possessed by most of the world?
Pair-Share
A
• Dominant traits found in my family
are __________.
B
• A dominant trait NOT found in my
______ is __________.
Word
Meaning
1. Withdrawn
2. Describes a trait
or an allele that is
expressed only
recessive when two recessive
alleles for the same
recessive
(adjective, noun) characteristic are
inherited.
Latin: recedere =
to go back
Examples
I hope she doesn’t keep
her feelings recessed.
My cousin’s green eyes
must be recessive since
both parents have
brown eyes.
• Tay Sachs disease is a
recessive disease which
means that a person has
to have both Tay Sachs
recessive alleles.
• Many people in the
Ashkenazi Jewish
community are carriers.
• When two parents who
are carriers have
children, each child has
a 1 in 4 chance of
getting the disease.
Writing Task:
Some diseases are recessive which
means an affected individual must have
both recessive alleles, one from each
parent.
Pair-Share
A
• A recessive disease that runs in my
family is __________.
B
• ____________ is a recessive trait.
Genetics Vocabulary
Group 2
Genotype
Phenotype
Homozygous
Heterozygous
Monohybrid
Dihybrid
Word
Meaning
Examples
1. The entire genetic The genotype for white
flowers on a pea plant
makeup of an
must be pp since it is a
organism.
recessive trait.
genotype
2. The combination
ge•no•type of genes for one or
(noun)
more specific trait.
Latin: genus= birth,
race, kind
Greek: typos = type
If that man has
Huntington disease, his
genotype must be Hh.
A A
• The specific genetic makeup of an
Genotype for
b B eye color, Bb
individual makes up its genotype.
C C
• If one could visually see a
D d
genotype, it might be represented
e e
by a series of letters, each one an
f F
allele, on the chromosomes.
G G
From Dad
From Mom
• If a gene for brown eyes is
represented by the letter b,
h H
brown would be B since it is
i
i
dominant. Therefore, blue would
J j
be b since it is recessive.
k k
• This explains how one can have a
L L
genotype Bb but still have brown
M m
eyes.
Chromosome 2
All of an individual’s DNA is its
genetic makeup or its genotype.
Writing Task: The genotype refers to the alleles
that makeup the genes on a
chromosome.
Pair-Share
A
• The genotype for a Tay Sachs carrier
is ____.
B
• A blue eyed individual might have
the genotype _______.
Word
phenotype
phe•no•type
(noun)
Meaning
An organism’s
appearance or
other detectable
characteristic that
results from the
organism’s
genotype and
environment.
Greek: phainein
= to show +
typos = type
Examples
The pea plant’s purple
flower is one of its many
observable phenotypes.
Luis’ light brown eyes are
a unique phenotype that
makes him stand out in a
crowd.
• Being a carrier of an allele
does not necessarily mean the
individual expresses that trait.
– If the trait is recessive, the
carrier will NOT show the
phenotype, as in blue eyes.
– If the trait is dominant, the
carrier WILL show the
phenotype, as in a cleft chin.
• Expression of the trait is the
phenotype. It’s the observable
trait that is seen with the eyes,
or seen as a disease.
If a person expresses the allele, it is
then called a phenotype. An
Writing Task:
example of a phenotype is having a
cleft chin.
Pair-Share
A
• A phenotype that I express is ____.
B
• A different phenotype that my partner
possesses is ___________________.
Word
Meaning
Examples
Individuals who have
the genotype AA are
Describes an
individual that has homozygous for that
identical alleles for trait.
a trait on both
Albino animals are
Homozygous homologous
homozygous for
ho•mo•zy•gous chromosomes.
defective fur or skin
(adjective)
pigment alleles.
Greek:
homos = same or
similar + zygous =
yoked (joined)
• Phenylketonuria (PKU) is a
homozygous recessive genetic
disorder.
• It’s characterized by an inability
to utilize the essential amino
acid phenylalanine due to a
malfunctioning enzyme that
can’t break it down.
• Without this enzyme,
phenylalanine accumulates in
the blood and body tissues.
• Untreated, it can cause mental
retardation and death.
• For an individual to develop PKU
they must be homozygous for
that allele.
An individual who is homozygous for a
particular gene has two copies of the
Writing Task: same allele. This can have serious
consequences if the gene results in a
genetic disorder such as PKU.
Pair-Share
A
• A homozygous recessive disorder is
____________.
B
• Homozygous alleles result in an
individual having ___________.
Word
Heterozygous
Het•ero•zy•gous
(noun)
Meaning
Examples
My uncle was
Describes an heterozygous for sickle
individual that cell anemia which
protected him from
has two
malaria.
different
alleles for a
I am heterozygous for
particular trait. brown eyes since my dad
has green eyes.
Greek:
Heteros= other +
zygous = yoked
(joined)
b b
B Bb Bb
b bb bb
• Polydactyly is a condition in which a person has more
than five fingers per hand or five toes per foot.
• The individual is heterozygous dominant for that
genetic trait.
• Anne Boleyn, was married to
Henry VIII, the King of England
in the 1500’s.
• It was reported that she had an
extra finger (polydactyly?)
which she kept hidden.
• When Henry wanted to marry
another woman, he accused her
of adultery with her own
brother and also used the extra
finger against her, saying that
she was a witch.
• She was beheaded by an expert
swordsman with one swift
stroke!
Writing Task:
Polydactyly is a heterozygous dominant
disorder where the dominant allele is
expressed giving the individual extra
fingers or toes.
Pair-Share
A
• An example of heterozygous alleles is
_____.
B
• Individuals heterozygous for dominant
freckles, F, have the genotype _____.
Word
Meaning
Examples
That new Toyota Prius
hybrid car gets a
whopping 51 MPG!
The offspring of
two animals or
plants of
hybrid
The mythological griffin
different
breeds,
hybrid
is a hybrid of a lion’s
varieties,
or
(noun, adjective)
body and an eagle’s
species.
head and wings.
Monohybrid
Dihybrid
Latin: hybrida =
uncommon
• One of the most common
hybrids in the animal
kingdom is a mule.
• A mule is a cross between a
male donkey (a jack) and a
female horse (a mare).
• Mules are always sterile.
Since donkeys have 62
chromosomes and horses
have 64, mules have 63. This
means they can’t produce
gametes since ½ of 63 = 31.5!
Mules are hybrids of male donkeys
and female horses. Mules can never
Writing Task:
reproduce since they have 63
chromosomes.
Pair-Share
A
• A common dog hybrid is a _______.
B
• A great mythological hybrid would be a
_____ which is a cross between ___.
Genetics Vocabulary
Group 3
Law of segregation
Law of independent assortment
Punnett square
Probability
Pedigree
Word
Meaning
1. To separate or
set apart from
others.
Segregation
segregation
(noun)
2. (Genetics)The
separation of
alleles for a
character that
occurs during
meiosis.
Latin: segregatus =
apart from herd
Examples
Sex cells contain one
copy of an allele for
each gene as the result
of the law of
segregation.
Racial segregation in
schools lasted until the
mid 1960’s.
• How does an individual have blue eyes when both parents
have brown eyes?
– This is the result of the law of segregation.
– Remember that the genotype for brown eyes can be BB or Bb.
– For an individual to have blue eyes they had to receive the two
bb alleles (one from each parent).
• In order for this to happen it meant that during gamete
formation (sperm or eggs), the B and b allele had to separate
become different gametes.
• During fertilization two gametes with b alleles would join
producing an individual with blue eyes.
Mom
B
B b
Dad
b
BB
B b
b
GAMETES
b b
Blue Eyed zygote
During meiosis, alleles for the same
characteristic will separate into
Writing Task:
different gametes according to the
law of segregation.
Pair-Share
A
• In orthodox synagogues there is
segregation between _____ and _____.
B
• I have observed segregation ________.
Word
Meaning
Examples
Students are invited to
lunch where an
assortment of
The act of
sandwiches and soda will
distributing into be served.
Assortment
assortment
groups of a like
kind.
(noun)
French: assortir =
to sort
Latin: sort = a
category, set
Our salad contains an
assortment of vegetables
including lettuce, celery,
tomatoes, and carrots.
Law of Independent Assortment
• This is one of Mendel’s laws of heredity. He
wanted to know whether the inheritance of
one gene was influenced by the inheritance of
a different character.
• He conducted dihybrid crosses using 2 pairs of
contrasting characters and found that alleles
of different genes separate independently of
one another during gamete formation.
• We now know that this law only applies to
genes that are located on different
chromosomes or that are far apart on the
same chromosome.
In dihybrid crosses, the alleles will
separate independently of one
Writing Task:
another demonstrating the law of
independent assortment
Pair-Share
A
• I have an assortment of
____________ in my ____________.
B
• The movie theater has an assortment
of _________________ in the lobby.
Word
Meaning
The likelihood
that a specific
event will occur.
It can be
Probability expressed in
prob·a·bil·i·ty words, decimals,
percentages and
(noun)
fractions.
Latin: probare =
to test, to prove
Examples
The probability of rain
in Los Angeles in July is
about one percent.
The probability of
winning the lottery is
about 18 million to 1!
Probability
• Probability is a very interesting branch of
mathematics because it is used to predict the
likelihood of random events. It is a deductive
science that studies uncertain quantities
related to random events.
• Gregor Mendel used the general rules of
probability to explain the basic principles of
heredity by breeding green peas in planned
experiments. After hundreds of experiments
he predicted that the outcome of any cross
with pure bred plants would always result in a
probability of 3 to 1 in the F2 generation.
• Probability = Number of one kind of possible outcome
Total number of all possible outcomes
Example:
• A coin tossed into the air will land on heads
(one possible outcome). The total of all
possible outcomes is two – heads or tails.
probability= 1
2
The cross between 2 pure bred pea
plants will always result in a
Writing Task:
probability of 3 to 1 in the F2
generation.
Pair-Share
A
• The probability of rain ___________ is
_________.
B
• The probability of getting an A in
_________ is ___________.
Word
Pedigree
ped·i·gree
(noun)
Meaning
1. A family history
that shows how a
trait is inherited
over several
generations.
2. The recorded
purity of a breed
of individuals.
Anglo French: pie
de grue = literally
foot of the crane
Examples
From my family
pedigree I traced
freckles back to Uncle
George.
A five generation
pedigree of my family
reveals where detached
earlobes originated.
• Many animals are bred for their
Pedigree
pedigrees.
• The Mastiff, one of the oldest
dog breeds, can be seen in
pictures dating back to 3000 BC.
• The dogs were bred for their
large size and strength.
• The Romans used them as
opponents against lions and
The meaning of pie de
gladiators.
grue literally comes from
the “foot of the crane” as • The British used them to fight
off predators on farms and as
the pedigree diagram
protectors of the home.
looks similar to the
branches coming out of a • They are also bred for their
crane's foot.
gentle temperament and fierce
loyalty.
Pedigree
Mastiff dogs have a pedigree that
pre- dates the Romans. They are
Writing Task:
bred for their strength, size,
temperament and fierce loyalty.
Pair-Share
A
• A pedigree can show how
_____________.
B
• The pedigree that runs through my
family is ________________.
Genetics Vocabulary
Group 4
Sex-linked trait
Color blind
Hemophilia
Fragile X syndrome
Muscular dystrophy
Word
Meaning
Examples
Martha didn’t know that
A trait that is
she could be a carrier of
determined by a gene a sex-linked trait if only
found on one of the males become infected
sex chromosomes, or with the disease.
Sex-linked
trait
(adjective)
such as the X
chromosome in
humans.
Latin: sexus = gender
Old English: hlanc =
chain
The sex-linked trait color
blindness affects about
8% of males in some
manner.
• Most sex-linked traits are a
result of a genetic defect of one
or more genes located on the X
chromosome.
– Since females require two X
chromosomes, one normal X will
override the defected one. Those
females are considered carriers.
– Since males only have one X
chromosomes, the inheritance of
the defective X from their
mothers results in them being
affected with the trait.
Word
Color blind
(adjective)
Meaning
An individual who
is affected with
partial or total
inability to
distinguish one or
more chromatic
colors, usually a
sex-linked trait.
Latin: celare = to
conceal + Old
German: blint = blind
Examples
Her husband picks out his
clothes in the morning
since he has red-green
color blindness.
Only 0.5% of women are
color blind as it is sexlinked and needs 2
affected X chromosomes.
• Humans see light with the retina which is
made up of rods and cones.
– Rods gives us our night vision but can’t
see color.
The colors of the rainbow as
viewed by a person with tritanopia.
– Cones are not useful at night but see
color during daylight hours.
• Three different types of cones ,
red, green, and blue, detect the
wavelengths of all the hues of the
The colors of the rainbow as viewed
by a person with protanopia.
rainbow.
• Defects in these cones cause
problems in detecting certain
colors.
The colors of the rainbow as viewed
by a person with deuteranopia.
The colors of the rainbow as viewed by a
person with no color vision deficiencies.
Word
Meaning
A sex-linked hereditary
blood defect
characterized by
hemophilia delayed clotting of the
he•mo•phil•i•a blood and consequent
difficulty in controlling
(noun)
bleeding even after
Hemophiliac minor injuries.
he•mo•phil•i•ac
(adjective)
Greek: haima = blood
+ philia = to love
Examples
Word
Fragile X
syndrome
Fragile X
syndrome
(noun)
Meaning
Examples
Word
Muscular
dystrophy
muscular
dystrophy
(noun)
Meaning
Examples
Genetics Vocabulary
Group 5
Autosomal
Albinism
Cystic fibrosis
Tay Sachs
Phenylketoneuria
Huntington’s disease
Dwarfism
Neurofibromatosis
Genetics Vocabulary
Group 6
Incomplete dominance
Polygenic inheritance
Codominance