1. Who is named the
“Father of Genetics?”
Gregor Mendel
2. Why did he use pea
plants?
To study the
inheritance of traits
What do pure bred, true breeding, and
homozygous mean?
All mean the same thing…
Both alleles are either
capitals or lower case.
AA
or
aa
What do hybrid and
heterozygous mean?
Actually mean the same thing…
A a
2 Alleles are
different
A a
A a
What type of offspring results when you
cross two pure “true” breeding parents
with different traits?
All HYBRID
(Gg)
offspring
result
Understand which is the P, F1, F2 generations
and how you get each.
What results when the offspring Tt (F1) of
true breeding parents self-pollinate (breed
with themselves)?
Tt x Tt
T
t
T
TT
Tt
t
Tt
tt
Genotype Ratio:
1 RR: 2 Rr: 1 rr
Phenotype Ratio:
3 Round: 1 Wrinkled
Probability= The chance of
something happening!
Chance of
getting heads
½ or 50%
More times you flip a penny,
the more likely you are to
get the “expected” outcome
(probability).
½ heads, ½ tails
If you toss a coin 6 times in a row, what is
the probability it will land heads for all 6
tosses?
½
x
½ x ½ x ½ x ½ x ½
1/64
During gamete formation, genes for different traits separate
without influencing the other.
“Law of Independent Assortment”
Foil each parent
to get 4 gametes
GgYy
GY
Gy
gY
gy
Complete
Dominance
The dominant trait (G)
masks (hides) the
recessive trait (g) and
only the dominant trait
shows up in the
phenotype.
Incomplete
Dominance
Neither trait is
dominant over the
other and a new trait is
displayed. BLENDING!!!
Red flowers crossed
with white flowers
make pink flowers.
Co-Dominance
Both traits are equally
displayed and neither is
dominant over the
other.
ABO blood types: A
blood x B blood =
AB blood
What are polygenic traits?
Traits that have a wide variety of color ranges
such as eye colors, hair color, skin color and
height.
Genotype
IAIA or IAi
IBIB or Ibi
IAIB
ii
Phenotype
A Blood
B Blood
AB Blood
O Blood
Describe the genotypes and phenotypes
of each blood type:
Co-Dominance
AB has same
Genotype & Phenotype
How many different gametes?
First determine how many different
letters are there for each letter type
then multiply!
AABbCcDdEEFFGgHh
1x2 x2 x2x1x1x2x2=
32 gametes
Can this parent AaBBccDdeeFfGgHH
have a child with the following
genotype? Why or why not?
NO, because the parent would need to
have a big E in their genotype in order
for the child to have both big E’s.
AABbCcDdEEFFGgHh
What is this picture called? Karyotype
What is this called? Karyotype
Shows:
• Autosomes = all chromosomes # 1 - 22
chromosome pairs (not sex chromosomes)
• Sex Chromosomes
XX= female or XY= male (# 23 pair)
• Homologous Chromosomes =
chromosomes that code for the same
traits and pair up with each other
• Inherited Disorders (ex: Down’s, Turner’s,
Kleinfelter’s, Super males/Super females)
What are the chromosome
pairs for a …
FEMALE
XX
MALE
XY
Non-disjunction –When chromosome pairs
don’t separate properly during Meiosis I
Can involve all chromosomes (sex, autosomes, homologous)
Down’s Syndrome (Trisomy 21)
Kleinfelter’s Syndrome
XXY
Turner’s Syndrome
XO
Super Female
Super Male XYY
Father
determines
sex of
offspring
50% chance of Boy XY
50% chance of Girl XX
Father
provides either
an X or a Y to
pair up with
the mother’s X
to make a boy
or girl
Know the term Sex-linked genes/traits and how the key and
Punnett square would look. What chromosome carries these
types of traits?
Sex-linked gene/trait – Traits linked to sex chromosomes such as
hemophilia or colorblindness
XBXb x XbY
Carrier Female x Male Colorblind
Sex-linked traits only carried on X
Y doesn’t carry traits!
XB
Xb
Xb
XBXb
XbXb
Y
XBY
XbY
Phenotypes:
1 Female/Carrier
1 Female/Colorblind
1 Male/Normal
1 Male/Colorblind
Normal Male
Normal Female
Female with Trait
Pedigree Chart
•Shows how a trait is passed from
one generation to the next
•Shows male or female
•Shows “no trait” “carries trait” or
“has trait”
Carrier Female
Male with Trait
4 Generations shown
Line = Marriage
REMEMBER: IN SEX-LINKED PEDIGREES, MALES CANNOT
BE CARRIERS OF THE TRAIT. THEY EITHER HAVE IT OR
NOT.
•Dominant- Trait is one that can mask (hide) the
recessive trait
•Recessive- Trait that gets masked (hidden) by the
dominant trait
•Punnett Square- Tool to determine possible
outcomes (probability)
•Homozygous- When both alleles look the same
(AA or aa)
• Heterozygous – When both alleles do not look
the same (Aa)
•Phenotype – The “physical” appearance (tall,
short)
•Genotype – Allele letters (Aa, TT, tt)
•Allele- Different forms of a gene
•Gametes- Sex Cells (egg & sperm)
•Gene- Part of a chromosome; codes for a trait
•Genetics- Study of how traits are passed
generation to generation
• Karyotype- Picture of all paired chromosomes looking for sex and the presence of abnormal # of
chromosomes
•Pedigree- Chart that shows passing of trait from
one generation to the next generation
•Probability - Chance of something happening
•Punnett Square- Chart showing possible offspring
from a parent cross.
•Co-dominance – Both alleles expressed EQUALLY
•Incomplete dominance – Blending of traits
•Diploid – Having 2 sets of chromosomes
•Haploid – Having 1 set of chromosomes
•Independent Assortment – Genes that separate have
no effect on the other’s inheritance
•Non-disjunction – When chromosomes don’t separate
•Segregation – Separation of alleles during gamete
formation
•Multiple Alleles – 2 or more genes code for a trait
•Polygenic Traits – Many genes working together to give
a trait such as eye color or height
Know how to do the following types of
crosses:
•Monohybrid Cross
•Dihybrid Cross
•Incomplete Dominance Cross
•Sex-linked Cross
Must show: key, parents’ genotypes,
possible gametes, Punnett square,
genotypes and phenotypes of offspring