Download Sex Chromosomes

1. Who is named the
“Father of Genetics?”
2. Why did he use pea
plants?
1. Gregor Mendel
2. To study the
inheritance of traits
and they
reproduced quickly
1. What is pure bred, true
breeding, or homozygous
mean?
2. What type of offspring results
when you cross two pure “true”
breeding parents with different
traits?
3. What are the offspring of two
parents called?
1. Both alleles are either dominant or
recessive AA or aa
2. All hybrid (Aa) offspring result
3. F1 generation
Aa
What results when the offspring (F1) of
true breeding parents self-pollinate?
Rr x Rr
R
r
R
RR
Rr
r
Rr
rr
Genotype Ratio: 1 RR: 2 Rr: 1 rr
Phenotype Ratio: 3 Round: 1 Wrinkled
1. What is probability?
2. What is the probability of
getting heads when you
flip a penny?
1. Probability: The chance
of something happening!
2. ½ or 50%
Why did we keep increasing
the number of flips of our
penny in the “Coin Toss”
lab?
The higher the number of
trials you perform, 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?
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
What is the “Principle of
Independent Assortment?”
During gamete formation, genes
for different traits separate
without influencing the other.
Foil each parent
to get 4 gametes
GgYy
GY
Gy
gY
gy
Be able to define:
Complete Dominance
Incomplete Dominance
Co-Dominance
Complete Dominance
The dominant trait (G)
over shadows 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
Describe the genotypes and
phenotypes of each blood
type:
Type A
Type B
Type AB
Type O
Describe the genotypes and phenotypes
of each blood type:
AB has same
genotype and
phenotype
What are polygenic traits?
What are polygenic traits?
Traits that have a wide variety of
color ranges such as eye colors,
hair color, skin color.
How many different gametes
would you get from the following
parent?
AABbCcDdEEFFGgHh
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?
AABbCcDdEEFFGgHh
Can this parent AaBBccDdeeFfGgHH
have a child with the following
genotype? Why?
NO, because the parent would need to
have a big E in their genotype in order
for the child to have 2 EE’s.
AABbCcDdEEFFGgHh
Know what forms from the sex cells in
females and males!
Male
4 Sperm
are
produced
Female
1 Egg and 3 polar
bodies are produced
Know the stages of Meiosis I & II
The paired,
homologous
chromosomes
come
together
during
Meiosis I to
make
Tetrads
The
chromatids
pull apart
during
Meiosis I I
4 genetically
different cells
result at the
end of
Meiosis
Haploid = one
set of
chromosomes
When does crossing over occur
during Meiosis?
Why is this important?
During
Prophase I
Important
for
GENETIC
DIVERSITY!!
X
S
Xt
X
X
T
s
Diploid Parent
SsTt
XX
S
s
XX
t
T
What are the four possible
combinations for the haploid
cells?
XX
S
l
l
S
S
T
T
t
ST
s
XX
t
l
l
l
l
T
s
St
l
l
t
s
sT
st
1.What is this picture called?
2.What 4 things are shown from this
picture?
1.What is this called? Karyotype
2.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/females)
What is non-disjunction?
Non-disjunction –When chromosome pairs
don’t separate properly during Meiosis I
Can involve all types of chromosomes (sex, autosomes, homologous)
What chromosomal disorder is
this on the #21 pair?
#21
Down’s Syndrome (Trisomy 21)
#21
What chromosomal disorder is
this on the sex chromosome?
XXY
Kleinfelter’s Syndrome
XXY
What chromosomal disorder is
this on the sex chromosome?
XO
Turner’s Syndrome
XO
Who determines the
sex of the offspring?
Mother or Father
Why?
What is probability of
getting a girl? A boy?
Father
determines
sex of
offspring
50% chance of Boy
50% chance of Girl
He provides
either an X or a
Y to pair up
with the
mother’s X to
make a boy or
girl
•What is this picture called?
•What do each of the shapes and shading
combinations represent?
•How many generations are shown?
Normal Male
Normal Female
Female with Trait
Pedigree Chart =
shows how a trait is
passed from one
generation to the
next.
3 Generations
Carrier Female
Male with Trait
Carrier Male
Line = Marriage
Be able to describe the differences
between:
Meiosis and Mitosis
Be able to describe the advantages and
disadvantages between:
Asexual and Sexual Reproduction
Mitosis
Meiosis
Somatic Cells – all body
cells
2 cells are made
Sex Cells - gametes
Diploid
Haploid
Asexual Reproduction
Sexual Reproduction
Advantages
 No mate needed for
reproduction
 Very fast reproduction time
 Lots of organisms
Disadvantages
 All organisms are alike,
No Genetic Diversity
4 cells are made
Advantages
 GENETIC DIVERSITY!
Disadvantages
 Need a mate for reproduction
 Slower reproduction time
 Fewer organisms
Know the term Sex-linked genes/traits
and how the key and Punnett square
would look. What chromosome carries
these types of traits?
XBXb x XbY
female carrier x male colorblind
XB
?
Xb
Xb
XBXb XbXb
Y
XBY
?
XbY
Phenotypes:
1 Female/Carrier
1 Female/Colorblind
1 Male/Normal
1 Male/Colorblind
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
female carrier x male colorblind
XB
Xb
Xb
XBXb
XbXb
Y
XBY
XbY
Phenotypes:
1 Female/Carrier
1 Female/Colorblind
1 Male/Normal
1 Male/Colorblind
Sex-linked traits only carried on X
Y doesn’t carry traits
Know the definitions of the following
vocabulary terms:
•Allele
•Gametes
•Genes
•Genetics
•Karyotype
•Pedigree
•Probability
•Punnett Square
•Allele- Different forms of a gene
•Gametes- Sex Cells (egg & sperm)
•Gene- Part of a chromosome; codes for traits
•Genetics- Study of how traits are passed
generation to generation
• Karyotype- Picture of all chromosomes matched
up - looking for sex and the presence of
abnormal # of chromosomes
•Pedigree- Family tree (picture) shows passing of
trait from one generation to the next generation
•Probability - Chance of something happening
•Punnett Square- Chart showing offspring’s trait
probabilities
Know the definitions of the following
vocabulary terms:
•Dominant
•Recessive
•Genotype
•Phenotype
•Heterozygous
•Homozygous
•Trait
•Homologous
•Dominant – Gene whose effect masks the partner
(recessive) trait
•Recessive – Gene whose effect is masked by
partner (dominant) trait
•Genotype – Genetic makeup of organism (letters)
•Phenotype – Trait expressed “physical” looks
•Heterozygous – Pair of different alleles (Rr)
•Homozygous – Pair of same kind of alleles (RR) (rr)
•Trait – Inherited characteristic (feature)
•Homologous – Pair of same kind of chromosomes
Know the definitions of the following
vocabulary terms:
•Co-dominance
•Incomplete dominance
•Diploid
•Haploid
•Independent Assortment
•Non-disjunction
•Segregation
•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
Understand which is the P, F1, F2
generations and how you get each.
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
Doing the different types of Punnett Squares!