GENETICS INTRODUCTION

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GENETICS INTRODUCTION

• History

1.The Father of Genetics
Gregor Mendel
2. Who was Gregor?
a. Austrian Monk
b. researched with pea plants
c. did his work around 1860
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GENETICS
4. Mendels Research Method a. Chose 7 pea
traits to research I. Fortunate for him
all traits followed simple
inheritance patterns
5. Mendels Four Laws a. Law of Unit
Characters I. Traits are controlled by
paired factors (genes) b. Law of
dominance and recessiveness I.
Dominant factors mask the effect of
recessive factors
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GENETICS
5. Mendels four Laws cont c. law of
segregation I. Unit factors separate
from each other BZZZZZ RULE!!!
d. law of independent assortment I. Unit
factors separate independently of
each other
6. Why Mendel is Amazing!! a. he
hypothesized all this before any
knowledge about chromosomes, genes, DNA,
etc
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GENETICS INTRODUCTION
7. Mendel Goes Public a. Gregor presented
his research to the scientific community
in 1862
How well do you think his work was received?
Some quotes abot Mendel Quote 1 Quote 2 Quote 3

• Nobody recognized his work until 1903
• Nobody understood the concepts
• 2. Darwin had stolen the scientific stage

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GENETICS TERMINOLOGY
Lets Review !!!
Homologues
Pairs of Shoes
Exact copies
Sister Chromatids
Sex Cells
Gametes
Diploid
Homologues present
Homologues absent
Haploid
Fertilized egg
Zygote
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GENETICS TERMINOLOGY
1. homozygous
The condition where both genes controlling a
trait are the same ( TT )
2. heterozygous
The condition where both genes controlling a
trait are different( Tt )
3. alleles
Genes found on corresponding loci on homologous
chromosomes
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GENETICS TERMINOLOGY
4. syngamy
Two gametes unite
5. dominance
The expressed gene in the heterozygous condition
( Tt )
6. recessiveness
The unexpressed gene in the heterozygous
condition ( Tt )
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GENETICS TERMINOLOGY
7. complete dominance
In the heterozygous condition one gene masks the
other gene completely
8. Incomplete dominance
Genes existing in the heterozygous condition are
equally expressed (ts)
9. autosomes
All chromosomes except sex chromosomes human
have 22 autosomes
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GENETICS TERMINOLOGY
10. Sex chromosomes
Chromosomes that determine gender
X female Y male
11. Genotype
Genetic make-up of organism all the genes of an
individual ( TT, Tt, tt )
12. Phenotype
The expressed traits or visible traits of an
individual ( hair color )
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Classic Genetics or Mendelian Genetics
Lets Review the Four Laws Do you remember?

• Law of Unit Characters
• Law of Dominance
• Law of Segregation
• 4. Law of Independent Assortment

Our Interpretation
3. Bzzzzz Rule
1. Shoe Rule
2. Strong Man Rule
4. Do your own thing
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Classic Genetics or Mendelian Genetics

• Mendel Terminology

• P Generation

Members of two different breeding lines that are
crossed (parental generation)
the first generation of hybrid offspring
resulting from a cross breeding

• F1 generation

• F2 generation

the second generation of hybrid offspring
resulting from a F1 cross.
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Classic Genetics or Mendelian Genetics
Predicting Genetic Outcomes
Step 1. Determine parental genotypes
a. Use capital letter for dominant trait
b. Use lower case letter for recessive trait
c. Know homozygous or heterozygous defintions
Step 2. Determine possible gametes
a. separate homologous chromosomes
BZZZZ Rule
Step 3. Determine possible gamete combos
a. Use a punnett square
b. Prediction of probable outcomes not actual
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Classic Genetics or Mendelian Genetics
Predicting Genetic Outcomes
Step 4. Determine results of cross
a. State as a fraction
b. State phenotype
c. Show possible genotypes
d. State as a probability (could be expected to
be)
CBETB
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Genetics Problems
Inheritance Pattern Complete Dominance
Definition?
In the heterozygous condition one gene masks the
homologous gene completely
Problem Guinea Pig Fur Color
In guinea pigs black fur (B) is dominant over
white fur (b). What would be the predicted
outcome of a cross between a homozygous black
guinea pig (male) and a white guinea (female)?
X
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Genetics Problems
Complete Dominance
Step one Determine genotypes
BB X bb
BZZZZ
Step two Determine gametes
B
B
b
b
Step three Determine zygotes
b
b
b


B
B
B
b
b

B
b
B
B
B
b
B
b
Reduce work!!!
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Genetics Problems
Complete Dominance
Step four Determine results
More Problems (complete these problems using the
four step method)
All pigs cbetb black Bb
1. What would be the predicted outcome of a cross
between a heterozygous black guinea pig (male)
and a white guinea (female)?
2. What would be the predicted outcome of a cross
between a heterozygous black guinea pig (male)
and a heterozygous black guinea (female)?
3. In peas, smooth pods (P) are dominsnt over
wrinkled (p). Predict the outcome of a cross
between a heterozygous smooth pea and a wrinkled
pea.
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Genetics Problems
Inheritance Pattern Incomplete Dominance

• Inheritance pattern where neither gene is
  dominant and the hybrid results in an
  intermediate phenotype
• b. Characterized by the presence of 3 phenotypes

Example Problems
In four oclocks red r and white w flowers
are incompletely dominant. The heterozygous
condition results in pink flowers. Predict the
outcome of a cross between a red four oclock
with a white.
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Genetics Problems
Incomplete Dominance Problems
1. rr x ww
BZZZ
2. r r w w
w
3.
rw
r
4. 100 cbetb pink rw
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Genetics Problems
Incomplete Dominance Problems
Predict the outcome of cross between a white cow
and a roan cow
On Your Mark
GO
Set
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Genetics Problems
Gender Inheritance

• What determines maleness?

• The BIG Y

• Boys are XY

• What determines femaleness?

• The BIG X

• Girls are XX

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Genetics Problems
Gender Inheritance

• What is the probability of having a girl or a boy?

1. XX x XY
BZZZ
2. X X X Y
X
Y
3.
X
XX
XY
4. 1/2 cbetb boys XY 1/2 cbetb girls XX
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Genetics Problems
Inheritance Pattern X-Linkage
Genes that are linked on the X chromosome

• Definition

• Example trait

hemophilia

• represent trait

Hemophilia gene
Dot represents X-linked trait

• Possible genotypes

Normal female
Carrier female
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Genetics Problems
X-Linkage

• Possible genotypes

affected male hemophilic
Normal male

• Example problem

• A hemophilic male is married to a carrier female.
  What is the probability of their children having
  hemophilia?

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Genetics Problems
X-Linkage

• Example problem

• A hemophilic male is married to a carrier
  female. What is the probability of their children
  having hemophilia?

4.
Females
1.
X
1/4 Females cbetb hemophilic
BZZZ
2.
1/4 Females cbetb carriers
3.
Males


1/4 males cbetb hemophilic
1/4 males cbetb hemophilic
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Genetics Problems
X-Linkage

• Other X-linked conditions

• color blindness

• which gender is effected more frequently?

• that would be boys

WHY?

• it only takes one recessive gene on the X
  chromosome, for girls it takes two

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Genetics Problems
Inheritance Pattern Co- Dominance
a. All the alleles controlling trait are
expressed equally and distinctly
b. Blood type is the classic example of
co-dominance
Human Blood Typing
a. 1800s lots of folks died after receiving
transfusions
b. Karl Landsteiner discovered blood groups in
1900/01
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing
a. What are the blood types?
AB
A
B
O
b. Why do people die if given the wrong blood?
i. Blood antigens
ii. antigens foreign proteins or a protein
that causes an immune response
a.) viruses, bacteria, organ donations, wrong
blood types, vaccines
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing
Type A blood
antibody B in plasma
Represents antigen A
Type B blood
antibody A in plasma
Represents antigen B
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing
What antibodies?
Type AB blood
None
What type is this?
What antibodies?
Type O blood
antibody A and B in plasma
What type is this?
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing
Blood Typing Animation
Blood Typing Game
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing
1. Mr. Smith is type O blood type. His wife is
type B and her father was type O. Predict the
blood type of any children they might have.
O


1/2 cbetb type B BO
BO
B
1/2 cbetb type O OO
OO
O
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Genetics Problems
Co- Dominance Inheritance Pattern
Human Blood Typing

• Another Blood Protein Group

• The Rh factor

• Rh factor named after the Rhesus monkey.

• You are either Rh or Rh -

DD

• Rh is dominant over Rh -

Rh
Dd

• Use D for Rh and d for Rh-

Rh-
dd

• So, what are all the genotypes?

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Genetics Problems
Two Character Crosses
a. Inheritance pattern focused on the behavior of
two traits located on different chromosomes
b. Use the same notations for alleles
Example Problems
a. In guinea pigs black coat is dominant over
white and rough coat is dominant over smooth.
Cross a pig homozygous for black and rough with a
white / smooth pig. B black, bwhite / R rough,
r smooth
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Genetics Problems
1. BBRR X bbrr
BZZZ
2. BR br

br
3.
BR
BbRr
4. 100 cbetb Black and Rough BbRr

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Genetics Problems
Another pig problem Cross a pig that is
heterozygous for black and rough with a pig that
is white and heterozygous rough
Eat more chicken please
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Genetics Problems
1. BbRr X bbRr
BZZZ

• BR br bR
  br
• Br bR

bR br
3.
BbRR
BbRr
BR Br bR br
BbRr
Bbrr
bbRR
bbRr
bbRr
bbrr
Black rough 3
white rough 3
Black smooth 1
white smooth 1
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Genetics Problems
4 Intrepretation
3/8 cbetb black rough BbR_ 1/8 cbetb black smooth
Bb rr 3/8 cbetb white rough bbR_ 1/8 cbetb white
smooth bbrr
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Genetics Problems
Two Character Crosses
Another pig problem Mr. Jeff Davis has type A
blood and his mama is O-. He is married and his
wife is AB-. What are the possible blood types
for any of the kids they might have?
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Genetics Problems
Gene Linkage
Definition Chromosomes carry more than one gene,
genes that are linked behave as one or like a
single trait cross.
Problem In the mythical creature of hippogriffs,
three traits are linked on the same chromosome
coat color, eye color and beak shape. Coat color
is incompletely dominant,there is white (w) and
black (b) and the heterozygous conditon produces
grey. Yellow eyes (Y) are dominant over orange(y)
and pointed beaks (B) are dominant over blunted
beaks (b). Set-up a cross between two hippogriffs
heterozygous for all three traits and predict the
probability of any offspring.
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Genetics Problems Pedigrees
Pedigree tracing of family traits
1. Pedigree Basics
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Genetics Problems Pedigrees
A
O
OO
AO
Start with known info
OO
AO
O
A
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A
A
B
AB
AO
AO
BO
AB
AB
OO
AO
B_
A_
A
AB
B
O
A
A
AB
OO
AB
AO
O
B
A
AB
AB
A_
BO
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Genetics Problems
You have a guinea pig that has black fur. If the
pig is homozygous for black it worth 10,000. if
it is heterozygous it is worth squat. How can
find out how much your pig is worth?
Test Cross
Definition crossing an unknown genotype with a
recessive to determine the unknown genotype.

• Why use a recessive?

known genotype
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Genetics Diseases Cystic Fibrosis
a. Controlled by a recessive gene
b. Not sex linked
c. Controlled by a recessive gene / cf
d. Possible Genotypes i. NN normal
ii. Ncf carrier iii. cfcf affected
individual
e. Symptoms i. production of excess mucus in
the respiratory and digestive system.
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Genetics Diseases Cystic Fibrosis
e. Symptoms i. production of excess mucus in
the respiratory and digestive system.
a.) causes breathing difficulties b.)
persistent infections c.) difficult weight
gain
f. Treatments i. mechanical removal of
mucus from lungs ii. breathing therapy
iii. enzyme therapy
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Genetics Diseases Cystic Fibrosis
g. What if I carry the cf gene? i. genetic
counseling ii. decide not to have children
Genetics Diseases Hemophilia

• Genetic control
• i. recessive gene that is X - linked

b. Possible genotypes
females
males
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Genetics Diseases Hemophilia
c. Symptoms
i. Mild to severe bleeding episodes, severity
depends on the individual
ii. Affected individuals cannot produce enough of
clotting factors VIII and IX
d. Treatments
i. Transfusions or injections of the missing
clotting factors
e. Significant History
i. Known as the Royal Disease
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Genetics Diseases Hemophilia
THE ROYAL DISEASE
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Genetic Diseases Sickle Cell Anemia

• Genetic control
• i. recessive gene

b. Possible genotypes Sc or sc (autosomal)
i. Sc Sc Sc sc sc sc
c. What happens?
i. Formation of abnormal hemoglobin
ii. Causes red blood cells to be malformed
iii. What problems would arise with red bloods
cells shaped like this?
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Genetic Diseases Sickle Cell Anemia
iii. What problems would arise with red bloods
cells shaped like this?
a. Inefficient carrier of oxygen
b. Physical difficulties arise with RBCs passing
through capillaries
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Genetic Diseases Sickle Cell Anemia
d. Physical Symptoms
i. Tired and weak
ii. Pain associated with poor blood flow more
susceptible to strokes and heart attacks
e. Affected Gene Pool (population)
i. people of African ancestory
ii. 1 in 12 African Americans affected
f. Heterozygous curiosity (Scsc)
i. These folks are immune to malaria
ii. Why?
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Genetic Diseases Tay Sachs
a. Genetic control
i. Recessive gene (autosomal)
ii. ts tay sachs gene
b. Possible Genotypes
i. TsTs Tsts tsts
c. What happens?
i. Build up of fat in the brain tissue
ii. Failure to produce enzyme which breaks down
this fat
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Genetic Diseases Tay Sachs
d. Physical symptoms
i. Progressive decline of nervous system
ii. Children usually die before age 3-5
iii. All affected individuals have a red spot in
the retina
e. Therapy
i. None
f. Affected Gene Pool
i. Eastern European Jewish ancestry
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Genetic Diseases Tay Sachs
g. Inheritance Pattern
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Genetic Diseases Tay Sachs
h. Heterozygous advantage
i. Heterozygous individuals seem to be immune to
TB
i. What do you do?
i. Prenatal diagnosis and abortion
ii. Mate selection
iii. Pre-implantation genetic diagnosis
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Genetic Diseases Huntingtons Disease
a. Genetic Control
i. dominant gene D (autosomal)
b. Possible Genotypes
i. DD Dd dd
c. What happens?
i. Production of a mutated protein that leads to
neural damage in the brain
d. Physical symptoms
i. Slow progressive loss of nervous control
starting in 30s and 40s
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Genetic Diseases Huntingtons Disease
e. Physical symptoms
ii. Life expectancy around 10-25 years after
disease onset
f. Therapy
f. No cure some therapies to control symptoms
g. Historical Background
i. Condition first identified by Ohio physician,
George Huntington
1892
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Genetic Diseases PKU (phenylketonuria)
a. Genetic Control
i. Recessive autosomal condition
ii. Genotypes N / normal n / pku
NN normal
Nn normal but carrier
nn PKU positive
b. Disease Mechanism
i. Normal metabolism the body converts
phenylalanine to tryosine via an enzyme
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Genetic Diseases PKU (phenylketonuria)
b. Disease Mechanism
i. Normal metabolism the body converts
phenylalanine to tryosine via an enzyme
ii. Abnormal metabolism, the body fails to
produce the enzyme so
phenylalanine to phenylketones
iii. This can lead to severe mental retardation
c. Treatment
i. Special diet low in phenylalanine
ii. Genetic counseling
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Genetic Diseases PKU (phenylketonuria)
d. Test to detect
i. Blood or urine at birth
Genetic Diseases Downs Syndrome
a. Genetic control
i. Trisomy 21 three 21st chromosomes
b. Non-disjunction event causes this condition
i. Non-disjunction?

• Sister chromatids fail to separate during
  anaphase 2

• Causes two 21st chromosomes to be in one gamete

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Genetic Diseases Downs Syndrome
c. Karyotype Chromosome make-up of an individual
d. Prenatal diagnostic test
i. amniocentesis sample of amniotic fluid drawn
from womb to analyze childs DNA
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Genetic Research Techniques
Genetic Oddities
Polydactylism Dominant allele
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Men of Genetics
First to identify the phenomenon known as
mutations
Hugo DeVries
Walter Sutton
First to observe segregation of chromosomes and
made the connection to Mendle
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Men of Genetics
Thomas Hunt Morgan discovered the x and y
chromosomes and x-linkage
Hermann Muller discovered that x-rays increase
mutation rates